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• Best approach for using Scanner Objects in Java?

  - by devjeetroy

  Although I'm more of a C++/ASM guy, I have to work with java as a part of my undergrad course at college. Our teacher taught us input using Scanner(System.in), and told us that if multiple functions are were taking user input, it would be advisable that a single Scanner object is passed around so as to reduce chances of the input stream getting screwed up. Now using this approach has gotten me into a situation where I'm trying to use a Scanner.nextLine(), and this statement does not wait for user input. It just moves on to the following statement. I figured there may be some residual cr/lf or other characters in the Scanner that might not have been retrieved are causing the problem. Here is the code. while(lineScanner.hasNext()) { if(isPlaceHolder(temp = lineScanner.next())) { temp = temp.replace("<",""); temp = temp.replace(">", ""); System.out.print("Enter "+aOrA(temp.charAt(0)) +" " +temp + " : "); temp = consoleInput.nextLine(); } outputFileStream.print(temp + " "); } All of the code is inside a function which receives a Scanner object consoleInput. Ok, so what happens when i run it is that when the program enters the if() the first time, It carries out theSystem.out.print, does not wait for user input, and moves on to the second time that it enters the 'if' block. This time, it takes the input and the rest of the program operates normally. What is even more surprising is that when i check the output file created by the program, it is perfect, just as i want to be. Almost as if the first time input using the scanner is correct. I have solved this problem by creating a new system.in Scanner in the function itself, instead of receiving the Scanner object as a parameter. But I am still very curious to know what the hell is happening and why it couldn't be solved using a simple Scanner.reset(). Would it be better to just simply create a Scanner Object for each function? Thanks, Devjeet PS. Although I know how to take input using fileinputstreams and the like, we are not supposed to use it with the homework.

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• Java: Multithreading & UDP Socket Programming

  - by Ravi

  I am new to multithreading & socket programming in Java. I would like to know what is the best way to implement 2 threads - one for receiving a socket and one for sending a socket. If what I am trying to do sounds absurd, pls let me know why! The code is largely inspired from Sun's tutorials online.I want to use Multicast sockets so that I can work with a multicast group. class server extends Thread { static protected MulticastSocket socket = null; protected BufferedReader in = null; public InetAddress group; private static class receive implements Runnable { public void run() { try { byte[] buf = new byte[256]; DatagramPacket pkt = new DatagramPacket(buf,buf.length); socket.receive(pkt); String received = new String(pkt.getData(),0,pkt.getLength()); System.out.println("From server@" + received); Thread.sleep(1000); } catch (IOException e) { System.out.println("Error:"+e); } catch (InterruptedException e) { System.out.println("Error:"+e); } } } public server() throws IOException { super("server"); socket = new MulticastSocket(4446); group = InetAddress.getByName("239.231.12.3"); socket.joinGroup(group); } public void run() { while(1>0) { try { byte[] buf = new byte[256]; DatagramPacket pkt = new DatagramPacket(buf,buf.length); //String msg = reader.readLine(); String pid = ManagementFactory.getRuntimeMXBean().getName(); buf = pid.getBytes(); pkt = new DatagramPacket(buf,buf.length,group,4446); socket.send(pkt); Thread t = new Thread(new receive()); t.start(); while(t.isAlive()) { t.join(1000); } sleep(1); } catch (IOException e) { System.out.println("Error:"+e); } catch (InterruptedException e) { System.out.println("Error:"+e); } } //socket.close(); } public static void main(String[] args) throws IOException { new server().start(); //System.out.println("Hello"); } }

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• Linked lists in Java - help with assignment

  - by user368241

  Representation of a string in linked lists In every intersection in the list there will be 3 fields : The letter itself. The number of times it appears consecutively. A pointer to the next intersection in the list. The following class CharNode represents a intersection in the list : public class CharNode { private char _data; private int _value; private charNode _next; public CharNode (char c, int val, charNode n) { _data = c; _value = val; _next = n; } public charNode getNext() { return _next; } public void setNext (charNode node) { _next = node; } public int getValue() { return _value; } public void setValue (int v) { value = v; } public char getData() { return _data; } public void setData (char c) { _data = c; } } The class StringList represents the whole list : public class StringList { private charNode _head; public StringList() { _head = null; } public StringList (CharNode node) { _head = node; } } Add methods to the class StringList according to the details : (I will add methods gradually according to my specific questions) (Pay attention, these are methods from the class String and we want to fulfill them by the representation of a string by a list as explained above) public int indexOf (int ch) - returns the index in the string it is operated on of the first appeareance of the char "ch". If the char "ch" doesn't appear in the string, returns -1. If the value of fromIndex isn't in the range, returns -1. Pay attention to all the possible error cases. Write what is the time complexity and space complexity of every method that you wrote. Make sure the methods you wrote are effective. It is NOT allowed to use ready classes of Java. It is NOT allowed to move to string and use string operations. Here is my try to write the method indexOf (int ch). Kindly assist me with fixing the bugs so I can move on. public int indexOf (int ch) { int count = 0; charNode pose = _head; if (pose == null ) { return -1; } for (pose = _head; pose!=null && pose.getNext()!='ch'; pose = pose.getNext()) { count++; } if (pose!=null) return count; else return -1; }

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• Graph Tour with Uniform Cost Search in Java

  - by user324817

  Hi. I'm new to this site, so hopefully you guys don't mind helping a nub. Anyway, I've been asked to write code to find the shortest cost of a graph tour on a particular graph, whose details are read in from file. The graph is shown below: http://img339.imageshack.us/img339/8907/graphr.jpg This is for an Artificial Intelligence class, so I'm expected to use a decent enough search method (brute force has been allowed, but not for full marks). I've been reading, and I think that what I'm looking for is an A* search with constant heuristic value, which I believe is a uniform cost search. I'm having trouble wrapping my head around how to apply this in Java. Basically, here's what I have: Vertex class - ArrayList<Edge> adjacencies; String name; int costToThis; Edge class - final Vertex target; public final int weight; Now at the moment, I'm struggling to work out how to apply the uniform cost notion to my desired goal path. Basically I have to start on a particular node, visit all other nodes, and end on that same node, with the lowest cost. As I understand it, I could use a PriorityQueue to store all of my travelled paths, but I can't wrap my head around how I show the goal state as the starting node with all other nodes visited. Here's what I have so far, which is pretty far off the mark: public static void visitNode(Vertex vertex) { ArrayList<Edge> firstEdges = vertex.getAdjacencies(); for(Edge e : firstEdges) { e.target.costToThis = e.weight + vertex.costToThis; queue.add(e.target); } Vertex next = queue.remove(); visitNode(next); } Initially this takes the starting node, then recursively visits the first node in the PriorityQueue (the path with the next lowest cost). My problem is basically, how do I stop my program from following a path specified in the queue if that path is at the goal state? The queue currently stores Vertex objects, but in my mind this isn't going to work as I can't store whether other vertices have been visited inside a Vertex object. Help is much appreciated! Josh

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• Java Scanner class reading strings

  - by Max

  I've created a scanner class to read through the text file and get the value what I'm after. Let's assume that I have a text file contains 1 : Fnjiei : ID 7868860 : Age 18 2 : Oipuiieerb : ID 334134 : Age 39 3 : Enekaree : ID 6106274 : Age 31 I'm trying to get a name and id number and age, but everytime I try to run my code it gives me an exception. Here's my code. Any suggestion from java gurus?:) public void readFile(String fileName)throws IOException{ Scanner input = null; input = new Scanner(new BufferedReader(new FileReader(fileName))); try { while (input.hasNextLine()){ int howMany = 3; System.out.println(howMany); String userInput = input.nextLine(); String name = ""; String idS = ""; String ageS = ""; int id; int age; int count=0; for (int j = 0; j <= howMany; j++){ for (int i=0; i < userInput.length(); i++){ if(count < 2){ // for name if(Character.isLetter(userInput.charAt(i))){ name+=userInput.charAt(i); // store the name }else if(userInput.charAt(i)==':'){ count++; i++; } }else if(count == 2){ // for id if(Character.isDigit(userInput.charAt(i))){ idS+=userInput.charAt(i); // store the id } else if(userInput.charAt(i)==':'){ count++; i++; } }else if(count == 3){ // for age if(Character.isDigit(userInput.charAt(i))){ ageS+=userInput.charAt(i); // store the age } } id = Integer.parseInt(idS); // convert id to integer age = Integer.parseInt(ageS); // convert age to integer Fighters newFighters = new Fighters(id, name, age); fighterList.add(newFighters); } userInput = input.nextLine(); } } }finally{ if (input != null){ input.close(); } } } My appology if my mere code begs to be changed.

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• refactoring this function in Java

  - by Joel

  Hi folks, I'm learning Java, and I know one of the big complaints about newbie programmers is that we make really long and involved methods that should be broken into several. Well here is one I wrote and is a perfect example. :-D. public void buildBall(){ /* sets the x and y value for the center of the canvas */ double i = ((getWidth() / 2)); double j = ((getHeight() / 2)); /* randomizes the start speed of the ball */ vy = 3.0; vx = rgen.nextDouble(1.0, 3.0); if (rgen.nextBoolean(.05)) vx = -vx; /* creates the ball */ GOval ball = new GOval(i,j,(2 *BALL_RADIUS),(2 * BALL_RADIUS)); ball.setFilled(true); ball.setFillColor(Color.RED); add(ball); /* animates the ball */ while(true){ i = (i + (vx* 2)); j = (j + (vy* 2)); if (i > APPLICATION_WIDTH-(2 * BALL_RADIUS)){ vx = -vx; } if (j > APPLICATION_HEIGHT-(2 * BALL_RADIUS)){ vy = -vy; } if (i < 0){ vx = -vx; } if (j < 0){ vy = -vy; } ball.move(vx + vx, vy + vy); pause(10); /* checks the edges of the ball to see if it hits an object */ colider = getElementAt(i, j); if (colider == null){ colider = getElementAt(i + (2*BALL_RADIUS), j); } if (colider == null){ colider = getElementAt(i + (2*BALL_RADIUS), j + (2*BALL_RADIUS)); } if (colider == null){ colider = getElementAt(i, j + (2*BALL_RADIUS)); } /* If the ball hits an object it reverses direction */ if (colider != null){ vy = -vy; /* removes bricks when hit but not the paddle */ if (j < (getHeight() -(PADDLE_Y_OFFSET + PADDLE_HEIGHT))){ remove(colider); } } } You can see from the title of the method that I started with good intentions of "building the ball". There are a few issues I ran up against: The problem is that then I needed to move the ball, so I created that while loop. I don't see any other way to do that other than just keep it "true", so that means any other code I create below this loop won't happen. I didn't make the while loop a different function because I was using those variables i and j. So I don't see how I can refactor beyond this loop. So my main question is: How would I pass the values of i and j to a new method: "animateBall" and how would I use ball.move(vx + vx, vy + vy); in that new method if ball has been declared in the buildBall method? I understand this is probably a simple thing of better understanding variable scope and passing arguments, but I'm not quite there yet...

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• Java array of arry [matrix] of an integer partition with fixed term

  - by user335209

  Hello, for my study purpose I need to build an array of array filled with the partitions of an integer with fixed term. That is given an integer, suppose 10 and given the fixed number of terms, suppose 5 I need to populate an array like this 10 0 0 0 0 9 0 0 0 1 8 0 0 0 2 7 0 0 0 3 ............ 9 0 0 1 0 8 0 0 1 1 ............. 7 0 1 1 0 6 0 1 1 1 ............ ........... 0 6 1 1 1 ............. 0 0 0 0 10 am pretty new to Java and am getting confused with all the for loops. Right now my code can do the partition of the integer but unfortunately it is not with fixed term public class Partition { private static int[] riga; private static void printPartition(int[] p, int n) { for (int i= 0; i < n; i++) System.out.print(p[i]+" "); System.out.println(); } private static void partition(int[] p, int n, int m, int i) { if (n == 0) printPartition(p, i); else for (int k= m; k > 0; k--) { p[i]= k; partition(p, n-k, n-k, i+1); } } public static void main(String[] args) { riga = new int[6]; for(int i = 0; i<riga.length; i++){ riga[i] = 0; } partition(riga, 6, 1, 0); } } the output I get it from is like this: 1 5 1 4 1 1 3 2 1 3 1 1 1 2 3 1 2 2 1 1 2 1 2 1 2 1 1 1 what i'm actually trying to understand how to proceed is to have it with a fixed terms which would be the columns of my array. So, am stuck with trying to get a way to make it less dynamic. Any help?

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• Customs toString in Java not giving desired output and throwing error

  - by user2972048

  I am writing a program in Java to accept and validate dates according to the Gregorian Calendar. My public boolean setDate(String aDate) function for an incorrect entry is suppose to change the boolean goodDate variable to false. That variable is suppose tell the toString function, when called, to output "Invalid Entry" but it does not. My public boolean setDate(int d, int m, int y) function works fine though. I've only included the problem parts as its a long piece of code. Thanks public boolean setDate(int day, int month, int year){ // If 1 <= day <= 31, 1 <= month <= 12, and 0 <= year <= 9999 & the day match with the month // then set object to this date and return true // Otherwise,return false (and do nothing) boolean correct = isTrueDate(day, month, year); if(correct){ this.day = day; this.month = month; this.year = year; return true; }else{ goodDate = false; return false; } //return false; } public boolean setDate(String aDate){ // If aDate is of the form "dd/mm/yyyy" or "d/mm/yyyy" // Then set the object to this date and return true. // Otherwise, return false (and do nothing) Date d = new Date(aDate); boolean correct = isTrueDate(d.day, d.month, d.year); if(correct){ this.day = d.day; this.month = d.month; this.year = d.year; return true; }else{ goodDate = false; return false; } } public String toString(){ // outputs a String of the form "dd/mm/yyyy" // where dd must be 2 digits (with leading zero if needed) // mm must be 2 digits (with leading zero if needed) // yyyy must be 4 digits (with leading zeros if needed) String day1; String month1; String year1; if(day<10){ day1 = "0" + Integer.toString(this.day); } else{ day1 = Integer.toString(this.day); } if(month<10){ month1 = "0" + Integer.toString(this.month); } else{ month1 = Integer.toString(this.month); } if(year<10){ year1 = "00" + Integer.toString(this.year); } else{ year1 = Integer.toString(this.year); } if(goodDate){ return day1 +"/" +month1 +"/" + year1; }else{ goodDate = true; return "Invalid Entry"; } } Thank you

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• Java issues with Apache 2.0 Agent 2.202 for RHEL5 Linux 64bit

  - by Richard

  In trying to install Apache 2.0 Agent 2.202 for RHEL5 Linux 64bit, the dialogue appears as follows. $ ./setup Error : java is not present in path. Please enter JAVAHOME path to pick up java:/usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0.x86_64/jre/ Launching installer... Attach to native process failed $ ./setup Error : java is not present in path. Please enter JAVAHOME path to pick up java:/usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0.x86_64/jre/lib ./setup: line 80: [: 107:: integer expression expected ./setup: line 83: [: 107:: integer expression expected Error : Incorrect java version (1.2.2 or above is needed). Please enter JAVAHOME path to pick up java: On the server we have the following JREs and I've tried both. $ sudo rpm -qa | egrep "(openjdk|icedtea)" java-1.6.0-openjdk-1.6.0.0-1.27.1.10.8.el5_8 $ find 2>/dev/null | grep -i '/jre/' ./usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre/bin/ ... ./usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0.x86_64/jre/ Any suggestions? I know I'm overlooking something. In previous searches I've only found one other posting that comes close but it has no responses (http://forum.parallels.com/showthread.php?t=76556).

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• JavaOne Tutorial Report - JavaFX 2 – A Java Developer’s Guide

  - by Janice J. Heiss

  Oracle Java Technology Evangelist Stephen Chin and Independent Consultant Peter Pilgrim presented a tutorial session intended to help developers get a handle on JavaFX 2. Stephen Chin, a Java Champion, is co-author of the Pro JavaFX Platform 2, while Java Champion Peter Pilgrim is an independent consultant who works out of London.NightHacking with Stephen ChinBefore discussing the tutorial, a note about Chin’s “NightHacking Tour,” wherein from 10/29/12 to 11/11/12, he will be traveling across Europe via motorcycle stopping at JUGs and interviewing Java developers and offering live video streaming of the journey. As he says, “Along the way, I will visit user groups, interviewing interesting folks, and hack on open source projects. The last stop will be the Devoxx conference in Belgium.”It’s a dirty job but someone’s got to do it. His trip will take him from the UK through the Netherlands, Germany, Switzerland, Italy, France, and finally to Devoxx in Belgium. He has interviews lined up with Ben Evans, Trisha Gee, Stephen Coulebourne, Martijn Verburg, Simon Ritter, Bert Ertman, Tony Epple, Adam Bien, Michael Hutterman, Sven Reimers, Andres Almiray, Gerrit Grunewald, Bertrand Boetzmann, Luc Duponcheel, Stephen Janssen, Cheryl Miller, and Andrew Phillips. If you expect to be in Chin’s vicinity at the end of October and in early November, by all means get in touch with him at his site and add your perspective. The more the merrier! Taking the JavaFX PlungeNow to the business at hand. The “JavaFX 2 – A Java Developer’s Guide” tutorial introduced Java developers to the JavaFX 2 platform from the perspective of seasoned Java developers. It demonstrated the breadth of the JavaFX APIs through examples that are built out in the course of the session in an effort to present the basic requirements in using JavaFX to build rich internet applications. Chin began with a quote from Oracle’s Christopher Oliver, the creator of F3, the original version of JavaFX, on the importance of GUIs:“At the end of the day, on the one hand we have computer systems, and on the other, people. Connecting them together, and allowing people to interact with computer systems in a compelling way, requires graphical user interfaces.”Chin explained that JavaFX is about producing an immersive application experience that involves cross-platform animation, video and charting. It can integrate Java, JavaScript and HTML in the same application. The new graphics stack takes advantage of hardware acceleration for 2D and 3D applications. In addition, we can integrate Swing applications using JFXPanel.He reminded attendees that they were building JavaFX apps using pure Java APIs that included builders for declarative construction; in addition, alternative languages can be used for simpler UI creation. In addition, developers can call upon alternative languages such as GroovyFX, ScalaFX and Visage, if they want simpler UI creation. He presented the fundamentals of JavaFX 2.0: properties, lists and binding and then explored primitive, object and FX list collection properties. Properties in JavaFX are observable, lazy and type safe. He then provided an example of property declaration in code.  Pilgrim and Chin explained the architectural structure of JavaFX 2 and its basic properties:JavaFX 2.0 properties – Primitive, Object, and FX List Collection properties. * Primitive Properties* Object Properties* FX List Collection Properties* Properties are:– Observable– Lazy– Type SafeChin and Pilgrim then took attendees through several participatory demos and got deep into the weeds of the code for the two-hour session. At the end, everyone knew a lot more about the inner workings of JavaFX 2.0.

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• Microsoft Declares the Future of ASP.NET is Web API

  - by sbwalker

  Sitting on a plane on my way home from Tech Ed 2012 in Orlando, I thought it would be a good time to jot down some key takeaways from this year’s conference. Some of these items I have known since the Microsoft MVP Summit which occurred in Redmond in late February ( but due to NDA restrictions I could not share them with the developer community at large ) and some of them are a result of insightful conversations with a wide variety of industry insiders and Microsoft employees at the conference. First, let’s travel back in time 4 years to the Microsoft MVP Summit in 2008. Microsoft was facing some heat from market newcomer Ruby on Rails and responded with a new web development framework of its own, ASP.NET MVC. At the Summit they estimated that MVC would only be applicable for ~10% of all new web development projects. Based on that prediction I questioned why they were investing such considerable resources for such a relative edge case, but my guess is that they felt it was an important edge case at the time as some of the more vocal .NET evangelists as well as some very high profile start-ups ( ie. Twitter ) had publicly announced their intent to use Rails. Microsoft made a lot of noise about MVC. In fact, they focused so much of their messaging and marketing hype around MVC that it appeared that WebForms was essentially dead. Yes, it may have been true that Microsoft continued to invest in WebForms, but from an outside perspective it really appeared that MVC was the only framework getting any real attention. As a result, MVC started to gain market share. An inside source at Microsoft told me that MVC usage has grown at a rate of about 5% per year and now sits at ~30%. Essentially by focusing so much marketing effort on MVC, Microsoft actually created a larger market demand for it.  This is because in the Microsoft ecosystem there is somewhat of a bandwagon mentality amongst developers. If Microsoft spends a lot of time talking about a specific technology, developers get the perception that it must be really important. So rather than choosing the right tool for the job, they often choose the tool with the most marketing hype and then try to sell it to the customer. In 2010, I blogged about the fact that MVC did not make any business sense for the DotNetNuke platform. This was because our ecosystem relied on third party extensions which were dependent on the WebForms model. If we migrated the core to MVC it would mean that all of the third party extensions would no longer be compatible, which would be an irresponsible business decision for us to make at the expense of our users and customers. However, this did not stop the debate from continuing to occur in our ecosystem. Clearly some developers had drunk Microsoft’s Kool-Aid about MVC and were of the mindset, to paraphrase an old Scottish saying, “If its not MVC, it’s crap”. Now, this is a rather ignorant position to take as most of the benefits of MVC can be achieved in WebForms with solid architecture and responsible coding practices. Clean separation of concerns, unit testing, and direct control over page output are all possible in the WebForms model – it just requires diligence and discipline. So over the past few years some horror stories have begun to bubble to the surface of software development projects focused on ground-up rewrites of web applications for the sole purpose of migrating from WebForms to MVC. These large scale rewrites were typically initiated by engineering teams with only a single argument driving the business decision, that Microsoft was promoting MVC as “the future”. These ill-fated rewrites offered no benefit to end users or customers and in fact resulted in a less stable, less scalable and more complicated systems – basically taking one step forward and two full steps back. A case in point is the announcement earlier this week that a popular open source .NET CMS provider has decided to pull the plug on their new MVC product which has been under active development for more than 18 months and revert back to WebForms. The availability of multiple server-side development models has deeply fragmented the Microsoft developer community. Some folks like to compare it to the age-old VB vs. C# language debate. However, the VB vs. C# language debate was ultimately more of a religious war because at least the two dominant programming languages were compatible with one another and could be used interchangeably. The issue with WebForms vs. MVC is much more challenging. This is because the messaging from Microsoft has positioned the two solutions as being incompatible with one another and as a result web developers feel like they are forced to choose one path or another. Yes, it is true that it has always been technically possible to use WebForms and MVC in the same project, but the tooling support has always made this feel “dirty”. The fragmentation has also made it difficult to attract newcomers as the perceived barrier to entry for learning ASP.NET has become higher. As a result many new software developers entering the market are gravitating to environments where the development model seems more simple and intuitive ( ie. PHP or Ruby ). At the same time that the Web Platform team was busy promoting ASP.NET MVC, the Microsoft Office team has been promoting Sharepoint as a platform for building internal enterprise web applications. Sharepoint has great penetration in the enterprise and over time has been enhanced with improved extensibility capabilities for software developers. But, like many other mature enterprise ASP.NET web applications, it is built on the WebForms development model. Similar to DotNetNuke, Sharepoint leverages a rich third party ecosystem for both generic web controls and more specialized WebParts – both of which rely on WebForms. So basically this resulted in a situation where the Web Platform group had headed off in one direction and the Office team had gone in another direction, and the end customer was stuck in the middle trying to figure out what to do with their existing investments in Microsoft technology. It really emphasized the perception that the left hand was not speaking to the right hand, as strategically speaking there did not seem to be any high level plan from Microsoft to ensure consistency and continuity across the different product lines. With the introduction of ASP.NET MVC, it also made some of the third party control vendors scratch their heads, and wonder what the heck Microsoft was thinking. The original value proposition of ASP.NET over Classic ASP was the ability for web developers to emulate the highly productive desktop development model by using abstract components for creating rich, interactive web interfaces. Web control vendors like Telerik, Infragistics, DevExpress, and ComponentArt had all built sizable businesses offering powerful user interface components to WebForms developers. And even after MVC was introduced these vendors continued to improve their products, offering greater productivity and a superior user experience via AJAX to what was possible in MVC. And since many developers were comfortable and satisfied with these third party solutions, the demand remained strong and the third party web control market continued to prosper despite the availability of MVC. While all of this was going on in the Microsoft ecosystem, there has also been a fundamental shift in the general software development industry. Driven by the explosion of Internet-enabled devices, the focus has now centered on service-oriented architecture (SOA). Service-oriented architecture is all about defining a public API for your product that any client can consume; whether it’s a native application running on a smart phone or tablet, a web browser taking advantage of HTML5 and Javascript, or a rich desktop application running on a PC. REST-based services which utilize the less verbose characteristics of JSON as a transport mechanism, have become the preferred approach over older, more bloated SOAP-based techniques. SOA also has the benefit of producing a cross-platform API, as every major technology stack is able to interact with standard REST-based web services. And for web applications, more and more developers are turning to robust Javascript libraries like JQuery and Knockout for browser-based client-side development techniques for calling web services and rendering content to end users. In fact, traditional server-side page rendering has largely fallen out of favor, resulting in decreased demand for server-side frameworks like Ruby on Rails, WebForms, and (gasp) MVC. In response to these new industry trends, Microsoft did what it always does – it immediately poured some resources into developing a solution which will ensure they remain relevant and competitive in the web space. This work culminated in a new framework which was branded as Web API. It is convention-based and designed to embrace native HTTP standards without copious layers of abstraction. This framework is designed to be the ultimate replacement for both the REST aspects of WCF and ASP.NET MVC Web Services. And since it was developed out of band with a dependency only on ASP.NET 4.0, it means that it can be used immediately in a variety of production scenarios. So at Tech Ed 2012 it was made abundantly clear in numerous sessions that Microsoft views Web API as the “Future of ASP.NET”. In fact, one Microsoft PM even went as far as to say that if we look 3-4 years into the future, that all ASP.NET web applications will be developed using the Web API approach. This is a fairly bold prediction and clearly telegraphs where Microsoft plans to allocate its resources going forward. Currently Web API is being delivered as part of the MVC4 package, but this is only temporary for the sake of convenience. It also sounds like there are still internal discussions going on in terms of how to brand the various aspects of ASP.NET going forward – perhaps the moniker of “ASP.NET Web Stack” coined a couple years ago by Scott Hanselman and utilized as part of the open source release of ASP.NET bits on Codeplex a few months back will eventually stick. Web API is being positioned as the unification of ASP.NET – the glue that is able to pull this fragmented mess back together again. The  “One ASP.NET” strategy will promote the use of all frameworks - WebForms, MVC, and Web API, even within the same web project. Basically the message is utilize the appropriate aspects of each framework to solve your business problems. Instead of navigating developers to a fork in the road, the plan is to educate them that “hybrid” applications are a great strategy for delivering solutions to customers. In addition, the service-oriented approach coupled with client-side development promoted by Web API can effectively be used in both WebForms and MVC applications. So this means it is also relevant to application platforms like DotNetNuke and Sharepoint, which means that it starts to create a unified development strategy across all ASP.NET product lines once again. And so what about MVC? There have actually been rumors floated that MVC has reached a stage of maturity where, similar to WebForms, it will be treated more as a maintenance product line going forward ( MVC4 may in fact be the last significant iteration of this framework ). This may sound alarming to some folks who have recently adopted MVC but it really shouldn’t, as both WebForms and MVC will continue to play a vital role in delivering solutions to customers. They will just not be the primary area where Microsoft is spending the majority of its R&D resources. That distinction will obviously go to Web API. And when the question comes up of why not enhance MVC to make it work with Web API, you must take a step back and look at this from the higher level to see that it really makes no sense. MVC is a server-side page compositing framework; whereas, Web API promotes client-side page compositing with a heavy focus on web services. In order to make MVC work well with Web API, would require a complete rewrite of MVC and at the end of the day, there would be no upgrade path for existing MVC applications. So it really does not make much business sense. So what does this have to do with DotNetNuke? Well, around 8-12 months ago we recognized the software industry trends towards web services and client-side development. We decided to utilize a “hybrid” model which would provide compatibility for existing modules while at the same time provide a bridge for developers who wanted to utilize more modern web techniques. Customers who like the productivity and familiarity of WebForms can continue to build custom modules using the traditional approach. However, in DotNetNuke 6.2 we also introduced a new Service Framework which is actually built on top of MVC2 ( we chose to leverage MVC because it had the most intuitive, light-weight REST implementation in the .NET stack ). The Services Framework allowed us to build some rich interactive features in DotNetNuke 6.2, including the Messaging and Notification Center and Activity Feed. But based on where we know Microsoft is heading, it makes sense for the next major version of DotNetNuke ( which is expected to be released in Q4 2012 ) to migrate from MVC2 to Web API. This will likely result in some breaking changes in the Services Framework but we feel it is the best approach for ensuring the platform remains highly modern and relevant. The fact that our development strategy is perfectly aligned with the “One ASP.NET” strategy from Microsoft means that our customers and developer community can be confident in their current and future investments in the DotNetNuke platform.

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• java.lang.RuntimeException: Unable to start activity ComponentInfo cannot be cast to android.widget.ZoomControls

  - by Hwl

  I'm new to android development, hope you all can help me. I got this androidVNC viewer source code from internet. When i'm running the androidVNC application in the emulator, it will exit automatically then i get following errors in LogCat. Can anyone one help me? Thanks. FATAL EXCEPTION: main java.lang.RuntimeException: Unable to start activity ComponentInfo{android.androidVNC/android.androidVNC.VncCanvasActivity}: java.lang.ClassCastException: com.antlersoft.android.zoomer.ZoomControls cannot be cast to android.widget.ZoomControls at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980) at android.app.ActivityThread.access$600(ActivityThread.java:122) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4340) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) at dalvik.system.NativeStart.main(Native Method) Caused by: java.lang.ClassCastException: com.antlersoft.android.zoomer.ZoomControls cannot be cast to android.widget.ZoomControls at android.androidVNC.VncCanvasActivity.onCreate(VncCanvasActivity.java:585) at android.app.Activity.performCreate(Activity.java:4465) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919) ... 11 more This is the ZoomControls java file: package com.antlersoft.android.zoomer; import android.content.Context; import android.util.AttributeSet; import android.view.LayoutInflater; import android.view.MotionEvent; import android.view.View; import android.view.animation.AlphaAnimation; import android.widget.ImageButton; import android.widget.LinearLayout; import android.widget.ZoomButton; public class ZoomControls extends LinearLayout { private final ZoomButton mZoomIn; private final ZoomButton mZoomOut; private final ImageButton mZoomKeyboard; public ZoomControls(Context context) { this(context, null); } public ZoomControls(Context context, AttributeSet attrs) { super(context, attrs); setFocusable(false); LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); inflater.inflate(R.layout.zoom_controls, this, // we are the parent true); mZoomIn = (ZoomButton) findViewById(R.id.zoomIn); mZoomOut = (ZoomButton) findViewById(R.id.zoomOut); mZoomKeyboard = (ImageButton) findViewById(R.id.zoomKeys); } public void setOnZoomInClickListener(OnClickListener listener) { mZoomIn.setOnClickListener(listener); } public void setOnZoomOutClickListener(OnClickListener listener) { mZoomOut.setOnClickListener(listener); } public void setOnZoomKeyboardClickListener(OnClickListener listener) { mZoomKeyboard.setOnClickListener(listener); } /* * Sets how fast you get zoom events when the user holds down the * zoom in/out buttons. */ public void setZoomSpeed(long speed) { mZoomIn.setZoomSpeed(speed); mZoomOut.setZoomSpeed(speed); } @Override public boolean onTouchEvent(MotionEvent event) { /* Consume all touch events so they don't get dispatched to the view * beneath this view. */ return true; } public void show() { fade(View.VISIBLE, 0.0f, 1.0f); } public void hide() { fade(View.GONE, 1.0f, 0.0f); } private void fade(int visibility, float startAlpha, float endAlpha) { AlphaAnimation anim = new AlphaAnimation(startAlpha, endAlpha); anim.setDuration(500); startAnimation(anim); setVisibility(visibility); } public void setIsZoomInEnabled(boolean isEnabled) { mZoomIn.setEnabled(isEnabled); } public void setIsZoomOutEnabled(boolean isEnabled) { mZoomOut.setEnabled(isEnabled); } @Override public boolean hasFocus() { return mZoomIn.hasFocus() || mZoomOut.hasFocus(); } } This is the zoom_controls XML file: <merge xmlns:android="http://schemas.android.com/apk/res/android"> <ZoomButton android:id="@+id/zoomOut" android:background="@drawable/btn_zoom_down" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <ImageButton android:id="@+id/zoomKeys" android:background="@android:drawable/ic_dialog_dialer" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <ZoomButton android:id="@+id/zoomIn" android:background="@drawable/btn_zoom_up" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </merge>

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• Good JDBC pattern

  - by Java Developer

  What is the good practice for database operation in Java application? Do you construct the DML syntax in the Java code and send the statements to DB engine for execution, or you just collect the parameters and then make a call to stored procedure with the parameters via java code? or neither because that's just not how to do it? can anyone give an example of a full database utility classes to do database operations in Java app? also what about the transaction manager? My assignment is to make database operation that is modular in Java. Thanks

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• Java: micro-optimizing array manipulation

  - by Martin Wiboe

  Hello all, I am trying to make a Java port of a simple feed-forward neural network. This obviously involves lots of numeric calculations, so I am trying to optimize my central loop as much as possible. The results should be correct within the limits of the float data type. My current code looks as follows (error handling & initialization removed): /** * Simple implementation of a feedforward neural network. The network supports * including a bias neuron with a constant output of 1.0 and weighted synapses * to hidden and output layers. * * @author Martin Wiboe */ public class FeedForwardNetwork { private final int outputNeurons; // No of neurons in output layer private final int inputNeurons; // No of neurons in input layer private int largestLayerNeurons; // No of neurons in largest layer private final int numberLayers; // No of layers private final int[] neuronCounts; // Neuron count in each layer, 0 is input // layer. private final float[][][] fWeights; // Weights between neurons. // fWeight[fromLayer][fromNeuron][toNeuron] // is the weight from fromNeuron in // fromLayer to toNeuron in layer // fromLayer+1. private float[][] neuronOutput; // Temporary storage of output from previous layer public float[] compute(float[] input) { // Copy input values to input layer output for (int i = 0; i < inputNeurons; i++) { neuronOutput[0][i] = input[i]; } // Loop through layers for (int layer = 1; layer < numberLayers; layer++) { // Loop over neurons in the layer and determine weighted input sum for (int neuron = 0; neuron < neuronCounts[layer]; neuron++) { // Bias neuron is the last neuron in the previous layer int biasNeuron = neuronCounts[layer - 1]; // Get weighted input from bias neuron - output is always 1.0 float activation = 1.0F * fWeights[layer - 1][biasNeuron][neuron]; // Get weighted inputs from rest of neurons in previous layer for (int inputNeuron = 0; inputNeuron < biasNeuron; inputNeuron++) { activation += neuronOutput[layer-1][inputNeuron] * fWeights[layer - 1][inputNeuron][neuron]; } // Store neuron output for next round of computation neuronOutput[layer][neuron] = sigmoid(activation); } } // Return output from network = output from last layer float[] result = new float[outputNeurons]; for (int i = 0; i < outputNeurons; i++) result[i] = neuronOutput[numberLayers - 1][i]; return result; } private final static float sigmoid(final float input) { return (float) (1.0F / (1.0F + Math.exp(-1.0F * input))); } } I am running the JVM with the -server option, and as of now my code is between 25% and 50% slower than similar C code. What can I do to improve this situation? Thank you, Martin Wiboe

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• boolean in java: what am I doing wrong?

  - by Cheesegraterr

  Hello, I am trying to make my boolean value work. I am new at programming java so I must be missing something simple. I am trying to make it so that if one of the tire pressures is below 35 or over 45 the system outputs "bad inflation" For class me must use a boolean which is what I tried. I cant figure out why this isnt working. No matter what I do the boolean is always true. Any tips? public class tirePressure { private static double getDoubleSystem1 () //Private routine to simply read a double in from the command line { String myInput1 = null; //Store the string that is read form the command line double numInput1 = 0; //Used to store the converted string into an double BufferedReader mySystem; //Buffer to store input mySystem = new BufferedReader (new InputStreamReader (System.in)); // creates a connection to system files or cmd try { myInput1 = mySystem.readLine (); //reads in data from console myInput1 = myInput1.trim (); //trim command cuts off unneccesary inputs } catch (IOException e) //checks for errors { System.out.println ("IOException: " + e); return -1; } numInput1 = Double.parseDouble (myInput1); //converts the string to an double return numInput1; //return double value to main program } static public void main (String[] args) { double TireFR; //double to store input from console double TireFL; double TireBR; double TireBL; boolean goodPressure; goodPressure = false; System.out.println ("Tire Pressure Checker"); System.out.println (" "); System.out.print ("Enter pressure of front left tire:"); TireFL = getDoubleSystem1 (); //read in an double from the user if (TireFL < 35 || TireFL > 45) { System.out.println ("Pressure out of range"); goodPressure = false; } System.out.print ("Enter pressure of front right tire:"); TireFR = getDoubleSystem1 (); //read in an double from the user if (TireFR < 35 || TireFR > 45) { System.out.println ("Pressure out of range"); goodPressure = false; } if (TireFL == TireFR) System.out.print (" "); else System.out.println ("Front tire pressures do not match"); System.out.println (" "); System.out.print ("Enter pressure of back left tire:"); TireBL = getDoubleSystem1 (); //read in an double from the user if (TireBL < 35 || TireBL > 45) { System.out.println ("Pressure out of range"); goodPressure = false; } System.out.print ("Enter pressure of back right tire:"); TireBR = getDoubleSystem1 (); //read in an double from the user if (TireBR < 35 || TireBR > 45) { System.out.println ("Pressure out of range"); goodPressure = false; } if (TireBL == TireBR) System.out.print (" "); else System.out.println ("Back tire pressures do not match"); if (goodPressure = true) System.out.println ("Inflation is OK."); else System.out.println ("Inflation is BAD."); System.out.println (goodPressure); } //mainmethod } // tirePressure Class

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• Radix sort in java help

  - by endif

  Hi i need some help to improve my code. I am trying to use Radixsort to sort array of 10 numbers (for example) in increasing order. When i run the program with array of size 10 and put 10 random int numbers in like 70 309 450 279 799 192 586 609 54 657 i get this out: 450 309 192 279 54 192 586 657 54 609 Don´t see where my error is in the code. class IntQueue { static class Hlekkur { int tala; Hlekkur naest; } Hlekkur fyrsti; Hlekkur sidasti; int n; public IntQueue() { fyrsti = sidasti = null; } // First number in queue. public int first() { return fyrsti.tala; } public int get() { int res = fyrsti.tala; n--; if( fyrsti == sidasti ) fyrsti = sidasti = null; else fyrsti = fyrsti.naest; return res; } public void put( int i ) { Hlekkur nyr = new Hlekkur(); n++; nyr.tala = i; if( sidasti==null ) f yrsti = sidasti = nyr; else { sidasti.naest = nyr; sidasti = nyr; } } public int count() { return n; } public static void radixSort(int [] q, int n, int d){ IntQueue [] queue = new IntQueue[n]; for (int k = 0; k < n; k++){ queue[k] = new IntQueue(); } for (int i = d-1; i >=0; i--){ for (int j = 0; j < n; j++){ while(queue[j].count() != 0) { queue[j].get(); } } for (int index = 0; index < n; index++){ // trying to look at one of three digit to sort after. int v=1; int digit = (q[index]/v)%10; v*=10; queue[digit].put(q[index]); } for (int p = 0; p < n; p++){ while(queue[p].count() != 0) { q[p] = (queue[p].get()); } } } } } I am also thinking can I let the function take one queue as an argument and on return that queue is in increasing order? If so how? Please help. Sorry if my english is bad not so good in it. Please let know if you need more details. import java.util.Random; public class RadTest extends IntQueue { public static void main(String[] args) { int [] q = new int[10]; Random r = new Random(); int t = 0; int size = 10; while(t != size) { q[t] = (r.nextInt(1000)); t++; } for(int i = 0; i!= size; i++) { System.out.println(q[i]); } System.out.println("Radad: \n"); radixSort(q,size,3); for(int i = 0; i!= size; i++) { System.out.println(q[i]); } } } Hope this is what you were talking about...

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• DoubleBuffering in Java

  - by DDP

  Hello there, I'm having some trouble implementing DoubleBuffer into my program. Before you faint from the wall of text, you should know that a lot of it is there just in case you need to know. The actual place where I think I'm having problems is in one method. I've recently looked up a tutorial on the gpwiki about double buffering, and decided to try and implement the code they had into the code I have that I'm trying to implement doublebuffer in. I get the following error: "java.lang.IllegalStateException: Component must have a valid peer". I don't know if it makes any difference if you know it or not, but the following is the code with the main method. This is just a Frame that displays the ChronosDisplay class inside it. I omitted irrelevant code with "..." public class CDM extends JFrame { public CDM(String str) { super("CD:M - "+str); try { ... ChronosDisplay theGame = new ChronosDisplay(str); ((Component)theGame).setFocusable(true); add(theGame); } catch(Exception e) { System.out.println("CDM ERROR: " +e); } } public static void main( String args[] ) { CDM run = new CDM("DP_Mini"); } } Here is the code where I think the problem resides (I think the problem is in the paint() method). This class is displayed in the CDM class public class ChronosDisplay extends Canvas implements Runnable { String mapName; public ChronosDisplay (String str) { mapName = str; new Thread(this).start(); setVisible(true); createBufferStrategy(2); } public void paint( Graphics window ) { BufferStrategy b = getBufferStrategy(); Graphics g = null; window.setColor(Color.white); try { g = b.getDrawGraphics(); paintMap(g); paintUnits(g); paintBullets(g); } finally { g.dispose(); } b.show(); Toolkit.getDefaultToolkit().sync(); } public void paintMap( Graphics window ) { TowerMap m = new TowerMap(); try { m = new TowerMap(mapName); for(int x=0; x<m.getRows()*50; x+=50) { for(int y = 0; y<m.getCols()*50; y+=50) { int tileType = m.getLocation(x/50,y/50); Image img; if(tileType == 0) { Tile0 t = new Tile0(x,y); t.draw(window); } ...// More similar if statements for other integers } catch(Exception e) ... } ...// Additional methods not shown here public void run() { try { while(true) { Thread.currentThread().sleep(20); repaint(); } } catch(Exception e) ... } } If you're curious (I doubt it matters), the draw() method in the Tile0 class is: public void draw( Graphics window ) { window.drawImage(img,getX(),getY(),50,50,null); } Any pointers, tips, or solutions are greatly appreciated. Thanks for your time! :D

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• Java multiple class compositing and boiler plate reduction

  - by h2g2java

  We all know why Java does/should not have multiple inheritance. So this is not questioning about what has already been debated till-cows-come-home. This discusses what we would do when we wish to create a class that has the characteristics of two or more other classes. Probably, most of us would do this to "inherit" from three classes. For simplicity, I left out the constructor.: class Car extends Vehicle { final public Transport transport; final public Machine machine; } So that, Car class directly inherits methods and objects of Vehicle class, but would have to refer to transport and machine explicitly to refer to objects instantiated in Transport and Machine. Car car = new Car(); car.drive(); // from Vehicle car.transport.isAmphibious(); // from Transport car.machine.getCO2Footprint(); // from Machine I thought this was a good idea until when I encounter frameworks that require setter and getter methods. For example, the XML <Car amphibious='false' footPrint='1000' model='Fordstatic999'/> would look for the methods setAmphibious(..), setFootPrint(..) and setModel(..). Therefore, I have to project the methods from Transport and Machine classes class Car extends Vehicle { final public Transport transport; final public Machine machine; public void setAmphibious(boolean b){ this.transport.setAmphibious(b); } public void setFootPrint(String fp){ this.machine.setFootPrint(fp); } } This is OK, if there were just a few characteristics. Right now, I am trying to adapt all of SmartGWT into GWT UIBinder, especially those classes that are not a GWT widget. There are lots of characteristics to project. Wouldn't it be nice if there exists some form of annotation framework that is like this: class Car extends Vehicle @projects {Transport @projects{Machine @projects Guzzler}} { /* No need to explicitly instantiate Transport, Machine or Guzzler */ .... } Where, in case of common names of characteristics exist, the characteristics of Machine would take precedence Guzzler's, and Transport's would have precedence over Machine's, and Vehicle's would have precedence over Transport's. The annotation framework would then instantiate Transport, Machine and Guzzler as hidden members of Car and expand to break-out the protected/public characteristics, in the precedence dictated by the @project annotation sequence, into actual source code or into byte-code. Preferably into byte-code. So that the setFootPrint method is found in both Machine and Guzzler, only that of Machine's would be projected. Questions: Don't you think this is a good idea to have such a framework? Does such a framework already exist? Tell me where/what. Is there an eclipse plugin that does it? Is there a proposal or plan anywhere that you know about such an annotation framework? It would be wonderful too, if the annotation/plugin framework lets me specify that boolean, int, or whatever else needs to be converted from String and does the conversion/parsing for me too. Please advise, somebody. I hope wording of my question was clear enough. Thx. Edited: To avoid OO enthusiasts jumping to conclusion, I have renamed the title of this question.

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• Java calendar getting weekdays not working

  - by Raptrex

  I am trying to get this to output all the weekdays (MON-FRI) between 5/16/2010 (a sunday) and 5/25/2010 (a tuesday). The correct output should be 17,18,19,20,21,24,25. However, the result im getting is 17,18,19,20,21,17,18,19. The other methods just split up the string the date is in import java.util.*; public class test { public static void main(String[] args) { String startTime = "5/16/2010 11:44 AM"; String endTime = "5/25/2010 12:00 PM"; GregorianCalendar startCal = new GregorianCalendar(); startCal.setLenient(true); String[] start = splitString(startTime); //this sets year, month day startCal.set(Integer.parseInt(start[2]),Integer.parseInt(start[0])-1,Integer.parseInt(start[1])); startCal.set(GregorianCalendar.HOUR, Integer.parseInt(start[3])); startCal.set(GregorianCalendar.MINUTE, Integer.parseInt(start[4])); if (start[5].equalsIgnoreCase("AM")) { startCal.set(GregorianCalendar.AM_PM, 0); } else { startCal.set(GregorianCalendar.AM_PM, 1); } GregorianCalendar endCal = new GregorianCalendar(); endCal.setLenient(true); String[] end = splitString(endTime); endCal.set(Integer.parseInt(end[2]),Integer.parseInt(end[0])-1,Integer.parseInt(end[1])); endCal.set(GregorianCalendar.HOUR, Integer.parseInt(end[3])); endCal.set(GregorianCalendar.MINUTE, Integer.parseInt(end[4])); if (end[5].equalsIgnoreCase("AM")) { endCal.set(GregorianCalendar.AM_PM, 0); } else { endCal.set(GregorianCalendar.AM_PM, 1); } for (int i = startCal.get(Calendar.DATE); i < endCal.get(Calendar.DATE); i++) { startCal.set(Calendar.DATE, i); startCal.set(Calendar.DAY_OF_WEEK, i); if (startCal.get(Calendar.DAY_OF_WEEK) == Calendar.MONDAY || startCal.get(Calendar.DAY_OF_WEEK) == Calendar.TUESDAY || startCal.get(Calendar.DAY_OF_WEEK) == Calendar.WEDNESDAY || startCal.get(Calendar.DAY_OF_WEEK) == Calendar.THURSDAY || startCal.get(Calendar.DAY_OF_WEEK) == Calendar.FRIDAY) { System.out.println("\t" + startCal.get(Calendar.DATE)); } } } private static String[] splitDate(String date) { String[] temp1 = date.split(" "); // split by space String[] temp2 = temp1[0].split("/"); // split by / //5/21/2010 10:00 AM return temp2; // return 5 21 2010 in one array } private static String[] splitTime(String date) { String[] temp1 = date.split(" "); // split by space String[] temp2 = temp1[1].split(":"); // split by : //5/21/2010 10:00 AM String[] temp3 = {temp2[0], temp2[1], temp1[2]}; return temp3; // return 10 00 AM in one array } private static String[] splitString(String date) { String[] temp1 = splitDate(date); String[] temp2 = splitTime(date); String[] temp3 = new String[6]; return dateFill(temp3, temp2[0], temp2[1], temp2[2], temp1[0], temp1[1], temp1[2]); } private static String[] dateFill(String[] date, String hours, String minutes, String ampm, String month, String day, String year) { date[0] = month; date[1] = day; date[2] = year; date[3] = hours; date[4] = minutes; date[5] = ampm; return date; } private String dateString(String[] date) { //return month+" "+day+", "+year+" "+hours+":"+minutes+" "+ampm //5/21/2010 10:00 AM return date[3]+"/"+date[4]+"/ "+date[5]+" "+date[0]+":"+date[1]+" "+date[2]; } }

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• Java CORBA Client Disconnects Immediately

  - by Benny

  I have built a Java CORBA application that subscribes to an event server. The application narrows and logs on just fine, but as soon as an event is sent to the client, it breaks with the error below. Please advise. 2010/04/25!13.00.00!E00555!enserver!EventServiceIF_i.cpp!655!PID(7390)!enserver - e._info=system exception, ID 'IDL:omg.org/CORBA/TRANSIENT:1.0' TAO exception, minor code = 54410093 (invocation connect failed; ECONNRESET), completed = NO EDIT: Please note, this only happens when running on some machines. It works on some, but not others. Even on the same platform (I've tried Windows XP/7 and CentOS linux) Some work, some don't... Here is the WireShark output...looks like the working PC is much more interactive with the network compared to the non-working PC. Working PC No. Time Source Destination Protocol Info 62 28.837255 10.10.10.209 10.10.10.250 TCP 50169 > 23120 [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=8 63 28.907068 fe80::5de0:8d21:937e:c649 ff02::1:3 LLMNR Standard query A isatap 64 28.907166 10.10.10.209 224.0.0.252 LLMNR Standard query A isatap 65 29.107259 10.10.10.209 10.255.255.255 NBNS Name query NB ISATAP<00> 66 29.227000 10.10.10.250 10.10.10.209 TCP 23120 > 50169 [SYN, ACK] Seq=0 Ack=1 Win=32768 Len=0 MSS=1260 WS=0 67 29.227032 10.10.10.209 10.10.10.250 TCP 50169 > 23120 [ACK] Seq=1 Ack=1 Win=66560 Len=0 68 29.238063 10.10.10.209 10.10.10.250 GIOP GIOP 1.1 Request s=326 id=5 (two-way): op=logon 69 29.291765 10.10.10.250 10.10.10.209 GIOP GIOP 1.1 Reply s=420 id=5: No Exception 70 29.301395 10.10.10.209 10.10.10.250 GIOP GIOP 1.1 Request s=369 id=6 (two-way): op=registerEventStat 71 29.348275 10.10.10.250 10.10.10.209 GIOP GIOP 1.1 Reply s=60 id=6: No Exception 72 29.405250 10.10.10.209 10.10.10.250 TCP 50170 > telnet [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=8 73 29.446055 10.10.10.250 10.10.10.209 TCP telnet > 50170 [SYN, ACK] Seq=0 Ack=1 Win=32768 Len=0 MSS=1260 WS=0 74 29.446128 10.10.10.209 10.10.10.250 TCP 50170 > telnet [ACK] Seq=1 Ack=1 Win=66560 Len=0 75 29.452021 10.10.10.209 10.10.10.250 TELNET Telnet Data ... 76 29.483537 10.10.10.250 10.10.10.209 TELNET Telnet Data ... 77 29.483651 10.10.10.209 10.10.10.250 TELNET Telnet Data ... 78 29.523463 10.10.10.250 10.10.10.209 TCP telnet > 50170 [ACK] Seq=4 Ack=5 Win=32768 Len=0 79 29.554954 10.10.10.209 10.10.10.250 TCP 50169 > 23120 [ACK] Seq=720 Ack=505 Win=66048 Len=0 Non-working PC No. Time Source Destination Protocol Info 1 0.000000 10.10.10.209 10.10.10.250 TCP 64161 > 23120 [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=8 2 2.999847 10.10.10.209 10.10.10.250 TCP 64161 > 23120 [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=8 3 4.540773 Cisco_3c:78:00 Cisco-Li_55:87:72 ARP Who has 10.0.0.1? Tell 10.10.10.209 4 4.540843 Cisco-Li_55:87:72 Cisco_3c:78:00 ARP 10.0.0.1 is at 00:1a:70:55:87:72 5 8.992284 10.10.10.209 10.10.10.250 TCP 64161 > 23120 [SYN] Seq=0 Win=8192 Len=0 MSS=1260

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• Ladder-like word game in Java

  - by sasquatch90

  I've found this question http://stackoverflow.com/questions/2844190/choosing-design-method-for-ladder-like-word-game and I would also like to do this kind of program. I've written some code but already have two issues. Here's what I already have : GRID : public class Grid { public Grid(){} public Grid( Element e ){} } ELEMENT : public class Element { final int INVISIBLE = 0; final int EMPTY = 1; final int FIRST_LETTER = 2; final int OTHER_LETTER = 3; private int state; private String letter; public Element(){} //empty block public Element(int state){ this("", 0); } //filled block public Element(String s, int state){ this.state = state; this.letter = s; } public static void changeState(int s){ } public int getState(){ return state; } public boolean equalLength(){ return true; } public boolean equalValue(){ return true; } @Override public String toString(){ return "["+letter+"]"; } } MAIN: import java.util.Scanner; public class Main { public static void main(String[] args){ Scanner sc = new Scanner(System.in); System.out.println("Height: "); while (!sc.hasNextInt()) { System.out.println("int, please!"); sc.next(); } final int height = sc.nextInt(); Grid[] game = new Grid[height]; for(int i = 1; i <= height; i++) { String s; do { System.out.println("Length " + i + ", please!"); s = sc.next(); } while (s.length() != i); Element[] line = new Element[s.length()+1]; Element single = null; String[] temp = null; //issue here temp = s.split(""); System.out.println("s.length: "+s.length()); System.out.println("temp.length: "+temp.length); // for(String str : temp){ System.out.println("str:"+str); } for (int k = 0 ; k < temp.length ; k++) { if( k == 0 ){ single = new Element(temp[k], 2); System.out.println("single1: "+single); } else{ single = new Element(temp[k], 3); System.out.println("single2: "+single); } line[k] = single; } for (Element l : line) { System.out.println("line:"+l); } //issue here game[i] = line; } // for (Grid g : game) { System.out.println(g); } } } And sample output for debug : Height: 3 Length 1, please! A s.length: 1 temp.length: 2 str: str:A single1: [] single2: [A] line:[] line:[A] Here's what I think it should work like. I grab a word from user. Next create Grid element for whole game. Then for each line I create Element[] array called line. I split the given text and here's the first problem. Why string.split() adds a whitespace ? You can see clearly in output that it is added for no reason. How can I get rid of it (now I had to add +1 to the length of line just to run the code). Continuing I'm throwing the splitted text into temporary String array and next from each letter I create Element object and throw it to line array. Apart of this empty space output looks fine. But next problem is with Grid. I've created constructor taking Element as an argument, but still I can't throw line as Grid[] elements because of 'incompatible types'. How can I fix that ? Am I even doing it right ? Maybe I should get rid of line as Element[] and just create Grid[][] ?

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• easiest and best way to make a server queue java

  - by houlahan

  i have a server at the moment which makes a new thread for every user connected but after about 6 people are on the server for more than 15 mins it tends to flop and give me java heap out of memory error i have 1 thread that checks with a mysql database every 30 seconds to see if any of the users currently logged on have any new messages. what would be the easiest way to implement a server queue? this is the my main method for my server: public class Server { public static int MaxUsers = 1000; //public static PrintStream[] sessions = new PrintStream[MaxUsers]; public static ObjectOutputStream[] sessions = new ObjectOutputStream[MaxUsers]; public static ObjectInputStream[] ois = new ObjectInputStream[MaxUsers]; private static int port = 6283; public static Connection conn; static Toolkit toolkit; static Timer timer; public static void main(String[] args) { try { conn = (Connection) Mysql.getConnection(); } catch (Exception ex) { Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex); } System.out.println("****************************************************"); System.out.println("* *"); System.out.println("* Cloud Server *"); System.out.println("* ©2010 *"); System.out.println("* *"); System.out.println("* Luke Houlahan *"); System.out.println("* *"); System.out.println("* Server Online *"); System.out.println("* Listening On Port " + port + " *"); System.out.println("* *"); System.out.println("****************************************************"); System.out.println(""); mailChecker(); try { int i; ServerSocket s = new ServerSocket(port); for (i = 0; i < MaxUsers; ++i) { sessions[i] = null; } while (true) { try { Socket incoming = s.accept(); boolean found = false; int numusers = 0; int usernum = -1; synchronized (sessions) { for (i = 0; i < MaxUsers; ++i) { if (sessions[i] == null) { if (!found) { sessions[i] = new ObjectOutputStream(incoming.getOutputStream()); ois[i]= new ObjectInputStream(incoming.getInputStream()); new SocketHandler(incoming, i).start(); found = true; usernum = i; } } else { numusers++; } } if (!found) { ObjectOutputStream temp = new ObjectOutputStream(incoming.getOutputStream()); Person tempperson = new Person(); tempperson.setFlagField(100); temp.writeObject(tempperson); temp.flush(); temp = null; tempperson = null; incoming.close(); } else { } } } catch (IOException ex) { System.out.println(1); Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex); } } } catch (IOException ex) { System.out.println(2); Logger.getLogger(Server.class.getName()).log(Level.SEVERE, null, ex); } } public static void mailChecker() { toolkit = Toolkit.getDefaultToolkit(); timer = new Timer(); timer.schedule(new mailCheck(), 0, 10 * 1000); } }

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• Problem with evaluating XPath expression in Java

  - by JSteve

  Can somebody help me find the mistake I am doing in evaluating following XPath expression? I want to get all "DataTable" nodes under the node "Model" in my xml through XPath. Here is my XML doc: <?xml version="1.0" encoding="UTF-8"?> <Root> <Application> <Model> <DataSet name="ds" primaryTable="Members" openRows="1"> <DataTable name="Members" openFor="write"> <DataColumn name="id" type="String" mandatory="true" primaryKey="true" valueBy="user"/> <DataColumn name="name" type="String" mandatory="true" valueBy="user"/> <DataColumn name="address" type="String" mandatory="false" valueBy="user"/> <DataColumn name="city" type="String" mandatory="false" valueBy="user"/> <DataColumn name="country" type="String" mandatory="false" valueBy="user"/> </DataTable> </DataSet> </Model> <View> <Composite> <Grid> <Label value="ID:" row="0" column="0" /> <Label value="Name:" row="1" column="0" /> <Label value="Address:" row="2" column="0" /> <Label value="City:" row="3" column="0" /> <Label value="Country:" row="4" column="0" /> <TextField name="txtId" row="0" column="1" /> <TextField name="txtName" row="1" column="1" /> <TextField name="txtAddress" row="2" column="1" /> <TextField name="txtCity" row="3" column="1" /> <TextField name="txtCountry" row="4" column="1" /> </Grid> </Composite> </View> </Application> </Root> Here the Java code to extract required node list: try { DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance(); domFactory.setNamespaceAware(true); domFactory.setIgnoringComments(true); domFactory.setIgnoringElementContentWhitespace(true); DocumentBuilder builder = domFactory.newDocumentBuilder(); Document dDoc = builder.parse("D:\TEST\myFile.xml"); XPath xpath = XPathFactory.newInstance().newXPath(); NodeList nl = (NodeList) xpath.evaluate("//Model//DataTable", dDoc, XPathConstants.NODESET); System.out.println(nl.getLength()); }catch (Exception ex) { System.out.println(ex.getMessage()); } There is no problem in loading and parsing xml file and I can see correct nodes in dDoc. Problem is with xpath that returns nothing on evaluating my expression. I tried many other expressions for testing purpose but every time resulting NodeList "nl" does not have any item

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• java if else statement

  - by user554320

  I am a new student who is trying to use java if else statements at the moment. I have attched my class and i need to say if this code get 0 errors for all 4 errors(error11, error12, error13 and error14), need to display the text "Answer". This code was working without the if else statements and there are 2 errors in those 2 lines. Please explain me how to do it? public static void deltaR() { int x; int x11, x12, x13, x14; int x21, x22, x23, x24; //inputs double w10, w11, w12;//weights for first neuron int d11, d12, d13, d14;//desired output for first neuron double net11, net12, net13, net14;//sum of weights times inputs int y11, y12, y13, y14;//outputs int error11, error12, error13, error14;//error //double w20, w21, w22;//weights for second neuron //int d21, d22, d23, d24;//desired output for second neuron //double net21, net22, net23, net24;//sum of weights times input //int y21, y22, y23, y24;//outputs //int error21, error22, error23, error24;//error if (error11 = 0, error12 = 0, error13 = 0, error14 = 0) { System.out.println("Answer"); } else if (error11 != 0, error12 != 0, error13 != 0, error14 != 0) { double coe=0.5;//learning coefficient x=1; x11=0; x12=0; x13=1; x14=1; x21=0; x22=1; x23=0; x24=1; d11= 0; d12= 1; d13= 0; d14= 1; w10=0.5; w11=-1; w12=1.5; net11=(x*w10 + x11*w11 + x21*w12); net12=(x*w10 + x12*w11 + x22*w12); net13=(x*w10 + x13*w11 + x23*w12); net14=(x*w10 + x14*w11 + x24*w12); if (net11>=0) y11=1; else y11=0; if (net12>=0) y12=1; else y12=0; if (net13>=0) y13=1; else y13=0; if (net14>=0) y14=1; else y14=0; error11=(d11-y11); error12=(d12-y12); error13=(d13-y13); error14=(d14-y14); System.out.println("net value 1: "+net11); System.out.println("net value 2: "+net12); System.out.println("net value 3: "+net13); System.out.println("net value 4: "+net14); System.out.println("output 1: "+y11); System.out.println("output 2: "+y12); System.out.println("output 3: "+y13); System.out.println("output 4: "+y14); System.out.println("error1: "+error11); System.out.println("error2: "+error12); System.out.println("error3: "+error13); System.out.println("error4: "+error14); } } }

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• AES encryption/decryption java bouncy castle explanation?

  - by Programmer0

  Can someone please explain what this program is doing pointing out some of the major points? I'm looking at the code and I'm completely lost. I just need explanation on the encryption/decryption phases. I think it generates an AES 192 key at one point but I'm not 100% sure. I'm not sure what the byte/ivBytes are used for either. import java.security.Key; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.spec.IvParameterSpec; public class RandomKey { public static void main(String[] args) throws Exception { byte[] input = new byte[] { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07 }; byte[] ivBytes = new byte[] { 0x00, 0x00, 0x00, 0x01, 0x04, 0x05, 0x06, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 }; //initializing a new initialization vector IvParameterSpec ivSpec = new IvParameterSpec(ivBytes); //what does this actually do? Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding", "BC"); //what does this do? KeyGenerator generator = KeyGenerator.getInstance("AES","BC"); //I assume this generates a key size of 192 bits generator.init(192); //does this generate a random key? Key encryptKey = generator.generateKey(); System.out.println("input: " +toHex(input)); //encryption phase cipher.init(Cipher.ENCRYPT_MODE, encryptKey, ivSpec); //what is this doing? byte[] cipherText = new byte[cipher.getOutputSize(input.length)]; //what is this doing? int ctLength = cipher.update(input, 0, input.length, cipherText,0); //getting the cipher text length i assume? ctLength += cipher.doFinal (cipherText, ctLength ); System.out.println ("Cipher: " +toHex(cipherText) + " bytes: " + ctLength); //decryption phase cipher.init(Cipher.DECRYPT_MODE, encryptKey, ivSpec); //storing the ciphertext in plaintext i'm assuming? byte[] plainText = new byte[cipher.getOutputSize(ctLength)]; int ptLength = cipher.update(cipherText, 0, ctLength, plainText, 0); //getting plaintextLength i think? ptLength= cipher.doFinal (plainText, ptLength); System.out.println("plain: " + toHex(plainText, ptLength)); } private static String digits = "0123456789abcdef"; public static String toHex(byte[] data, int length) { StringBuffer buf = new StringBuffer(); for (int i=0; i!= length; i++) { int v = data[i] & 0xff; buf.append(digits.charAt(v >>4)); buf.append(digits.charAt(v & 0xf)); } return buf.toString(); } public static String toHex(byte[] data) { return toHex(data, data.length); } }

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