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• How to enable services Discovery API in GoogleCL?

  - by Marcos

  There are bits and pieces of information all over the place but I'm trying to put it all together so that GoogleCL finally accesses more than the initial 7 services. Does anyone know of a step-by-step? Right now any attempt outside these result in the error message: google tasks list Did you specify the service correctly? Must be one of 'picasa', 'blogger', 'youtube', 'docs', 'contacts', 'calendar', 'finance' I installed GoogleCL from the Ubuntu repos, authenticated a few bundled services like contacts, docs etc. and those work great, giving me access to do certain operations like upload from the command line. I would really like to get it going to support tasks and all the other elegible Google services shown at https://code.google.com/apis/explorer/#_s=tasks Here are some guides/partial steps I've found: http://code.google.com/p/googlecl/wiki/DiscoveryManual (indicates needing to check it out updated GoogleCL from the subversion repository.) http://code.google.com/p/google-api-python-client/wiki/Installation easy_install --upgrade google-api-python-client http://code.google.com/p/googlecl/wiki/Install http://code.google.com/p/googlecl/source/checkout sudo -i cd /usr/local/src/ svn checkout http://googlecl.googlecode.com/svn/trunk/ googlecl-read-only cat googlecl-read-only/INSTALL.txt cd /usr/local/src/googlecl-read-only/ python setup.py install Result: $ google discovery list Traceback (most recent call last): File "/usr/bin/google", line 488, in run_interactive run_once(options, args) File "/usr/bin/google", line 540, in run_once options.config) File "/usr/bin/google", line 364, in import_service force_gdata_v1 = config.lazy_get(package.SECTION_HEADER, AttributeError: 'module' object has no attribute 'SECTION_HEADER'

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• Handling SEO for Infinite pages that cause external slow API calls

  - by Noam

  I have an 'infinite' amount of pages in my site which rely on an external API. Generating each page takes time (1 minute). Links in the site point to such pages, and when a users clicks them they are generated and he waits. Considering I cannot pre-create them all, I am trying to figure out the best SEO approach to handle these pages. Options: Create really simple pages for the web spiders and only real users will fetch the data and generate the page. A little bit 'afraid' google will see this as low quality content, which might also feel duplicated. Put them under a directory in my site (e.g. /non-generated/) and put a disallow in robots.txt. Problem here is I don't want users to have to deal with a different URL when wanting to share this page or make sense of it. Thought about maybe redirecting real users from this URL back to the regular hierarchy and that way 'fooling' google not to get to them. Again not sure he will like me for that. Letting him crawl these pages. Main problem is I can't control to rate of the API calls and also my site seems slower than it should from a spider's perspective (if he only crawled the generated pages, he'd think it's much faster). Which approach would you suggest?

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• BigDecimal precision not persisted with javax.persistence annotations

  - by dkaczynski

  I am using the javax.persistence API and Hibernate to create annotations and persist entities and their attributes in an Oracle 11g Express database. I have the following attribute in an entity: @Column(precision = 12, scale = 9) private BigDecimal weightedScore; The goal is to persist a decimal value with a maximum of 12 digits and a maximum of 9 of those digits to the right of the decimal place. After calculating the weightedScore, the result is 0.1234, but once I commit the entity with the Oracle database, the value displays as 0.12. I can see this by either by using an EntityManager object to query the entry or by viewing it directly in the Oracle Application Express (Apex) interface in a web browser. How should I annotate my BigDecimal attribute so that the precision is persisted correctly? Note: We use an in-memory HSQL database to run our unit tests, and it does not experience the issue with the lack of precision, with or without the @Column annotation.

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• How to get initial API right using TDD?

  - by Vytautas Mackonis

  This might be a rather silly question as I am at my first attempts at TDD. I loved the sense of confidence it brings and generally better structure of my code but when I started to apply it on something bigger than one-class toy examples, I ran into difficulties. Suppose, you are writing a library of sorts. You know what it has to do, you know a general way of how it is supposed to be implemented (architecture wise), but you keep "discovering" that you need to make changes to your public API as you code. Perhaps you need to transform this private method into strategy pattern (and now need to pass a mocked strategy in your tests), perhaps you misplaced a responsibility here and there and split an existing class. When you are improving upon existing code, TDD seems a really good fit, but when you are writing everything from scratch, the API you write tests for is a bit "blurry" unless you do a big design up front. What do you do when you already have 30 tests on the method that had its signature (and for that part, behavior) changed? That is a lot of tests to change once they add up.

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• Using Coherence API to get POF bytes

  - by Bruno.Borges

  Someone raised the question on how to use the Coherence API to get the bytes of an object in POF (Portable Object Format) programatically. So I came up with this small code that shows the very cool API simple usage :-)   SimplePofContext spc = new SimplePofContext();    spc.registerUserType(0, User.class, new UserSerializer());    // consider UserSerializer as an implementation of PofSerializer            User u = new User();    u.setId(21);    u.setName("Some Name");    u.setEmail("[email protected]");            ByteArrayOutputStream baos = new ByteArrayOutputStream();    DataOutput dataOutput = new DataOutputStream(baos);    BufferOutput bufferOutput = new WrapperBufferOutput(dataOutput);    spc.serialize(bufferOutput, u);            byte[] byteArray = baos.toByteArray();    System.out.println(Arrays.toString(byteArray));  Easy, isn't?

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• Authenticate native mobile app using a REST API

  - by Supercell

  I'm starting a new project soon, which is targeting mobile application for all major mobile platforms (iOS, Android, Windows). It will be a client-server architecture. The app is both informational and transactional. For the transactional part, they're required to have an account and log in before a transaction can be made. I'm new to mobile development, so I don't know how the authentication part is done on these platforms. The clients will communicate with the server through a REST API. Will be using HTTPS ofcourse. I haven't yet decided if I want the user to log in when they open the app, or only when they perform a transaction. I got the following questions: 1) Like the Facebook application, you only enter your credentials when you open the application for the first time. After that, you're automatically signed in every time you open the app. How does one accomplish this? Just simply by encrypting and storing the credentials on the device and sending them every time the app starts? 2) Do I need to authenticate the user for each (transactional) request made to the REST API or use a token based approach? Please feel free to suggest other ways for authentication. Thanks!

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• Google Currency Convertor JSON API

  - by Gopinath

  There are many live currency conversion services available on the web and the popular one’s among them are – Google, Yahoo, MSN & XE. Among all these four Google is the developer’s darling and it provides a simple JSON API that can be integrated in your applications.  http://www.google.com/ig/calculator?hl=en&q=1USD=?INR Using the API is very simple and it takes two parameters as input. The first parameter “hl” is the language code in which you want output. The second parameter “q” is the conversion query in the format <number><from currency code>=?<to currency code>. In the URL give above the query requests for conversion of 1 USD in INR. JSON output for the above query would be  similar to {lhs: "1 U.S. dollar",rhs: "54.4602984 Indian rupees",error: "",icc: true} Examples: 100 USD in INR  http://www.google.com/ig/calculator?hl=en&q=100USD=?INR Example 2: 1 GBP in INR http://www.google.com/ig/calculator?hl=en&q=1GBP=?INR Example 3: 1 USD in INR, output the data in French language http://www.google.com/ig/calculator?hl=fr&q=1USD=?INR   This is an undocumented service and expect changes at any time. But as long as it works, you got a programmatic way to convert currencies.

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• What are the potential problems with exposing the Facebook API secret?

  - by genehack

  I'm writing a little web utility that posts status updates to Twitter and/or Facebook. That involved creating 'applications' with both those services in order to get API keys and 'secrets'. My question is how protected I really need to keep those secrets -- in order for this to work at all, you seem to need the secret to interact with the authentication part of the service to grant the app access to your account and/or grant it permission to post updates on your behalf. Facebook's documentation says to protect the secret, but at least one other Facebook utility distributes the API key and secret in the source. It's important to note: this isn't your standard Facebook 'application' that runs within the context of Facebook, nor is it a standard "desktop"-style compiled app -- it's a web-based application intended to be run on your own web server. The audience for this is probably small and somewhat more sophisticated than average -- so, one technical alternative would be to require people to obtain their own API key and secret to use the app. That seems like a lot of work, however, and a fairly large barrier to entry to anybody using this. Anybody know or have any insight on what sort of trouble I'm letting myself in for if I put both the secrets and the API keys in the config for my app and check it into Github for all the world to see?

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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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• 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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• A very strange problem related to Flash and Java

  - by Nitesh Panchal

  Hello, I have created one simple program for showing webcam of the user. It works absolutely fine when i am running without integrating it in my java web application. But as soon as i copy paste the same files in Netbeans 6.8 and try to run it. My swf file is visible but the buttons in it are totally unclickable. I get the message of allow or deny showing webcam but the buttons are not clickable. It makes my application totally useless. I thought it's a minor issue but now it's getting on my nerves. I am trying it since 3 hours but didn't find any solution. I don't think anybody faced this issue till now that's why can't seem to find any thread in any forum on it in google. I am using Netbeans 6.8, Ubuntu, Glassfish V3 and JSF. Thanks in advance :). UPDATE:- It works fine on Windows XP. Then what can be the problem with Ubuntu? Any kind of permission rights that i need to give? 2nd UPDATE:- I think this is bug with Flash. I found that this code doesn't work :- <object classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=9,0,0,0" id="VideoConferenceAdmin" align="middle"> <param name="allowScriptAccess" value="sameDomain" /> <param name="wmode" value="opaque"/> <param name="allowFullScreen" value="false" /> <param NAME="FlashVars" VALUE="rootIp=localhost&amp;userName=admin&amp;roomName=test" /> <param name="movie" value="Conference/VideoConference.swf" /><param name="quality" value="high" /> <embed src="Conference/VideoConference.swf" wmode="window" FlashVars="rootIp=localhost&amp;userName=test&amp;roomName=test" quality="high" width="600" height="500" name="VideoConference" align="middle" allowScriptAccess="sameDomain" allowFullScreen="false" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" /> </object> And this one works :- <object classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=9,0,0,0" id="VideoConferenceAdmin" align="middle"> <param name="allowScriptAccess" value="sameDomain" /> <param name="wmode" value="opaque"/> <param name="allowFullScreen" value="false" /> <param NAME="FlashVars" VALUE="rootIp=localhost&amp;userName=admin&amp;roomName=test" /> <param name="movie" value="Conference/VideoConference.swf" /><param name="quality" value="high" /> <embed src="Conference/VideoConference.swf" wmode="window" FlashVars="rootIp=localhost&amp;userName=test&amp;roomName=test" quality="high" name="VideoConference" align="middle" allowScriptAccess="sameDomain" allowFullScreen="false" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" /> </object> As you can see, just by removing the height and width attribute the panels of Flash settings work fine. I know you will find me funny but i am not. You can check out on your own if you don't trust me. Now, my question would be, can anybody tell me how do i set height and width of swf? I want it to be 600px width and 500px height. Even the style attribute doesn't work. Can i set height and width from within Flash? because without explicitly setting height and width, it looks very small. I think this should be very easy for all now. Thanks in advance :)

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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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• 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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• Trying to sentinel loop this program. [java]

  - by roger34

  Okay, I spent all this time making this for class but I have one thing that I can't quite get: I need this to sentinel loop continuously (exiting upon entering x) so that the System.out.println("What type of Employee? Enter 'o' for Office " + "Clerical, 'f' for Factory, or 's' for Saleperson. Enter 'x' to exit." ); line comes back up after they enter the first round of information. Also, I can't leave this up long on the (very) off chance a classmate might see this and steal the code. Full code following: import java.util.Scanner; public class Project1 { public static void main (String args[]){ Scanner inp = new Scanner( System.in ); double totalPay; System.out.println("What type of Employee? Enter 'o' for Office " + "Clerical, 'f' for Factory, or 's' for Saleperson. Enter 'x' to exit." ); String response= inp.nextLine(); while (!response.toLowerCase().equals("o")&&!response.toLowerCase().equals("f") &&!response.toLowerCase().equals("s")&&!response.toLowerCase().equals("x")){ System.out.print("\nInvalid selection,please enter your choice again:\n"); response=inp.nextLine(); } char choice = response.toLowerCase().charAt( 0 ); switch (choice){ case 'o': System.out.println("Enter your hourly rate:"); double officeRate=inp.nextDouble(); System.out.println("Enter the number of hours worked:"); double officeHours=inp.nextDouble(); totalPay = officeCalc(officeRate,officeHours); taxCalc(totalPay); break; case 'f': System.out.println("How many Widgets did you produce during the week?"); double widgets=inp.nextDouble(); totalPay=factoryCalc(widgets); taxCalc(totalPay); break; case 's': System.out.println("What were your total sales for the week?"); double totalSales=inp.nextDouble(); totalPay=salesCalc(totalSales); taxCalc(totalPay); break; } } public static double taxCalc(double totalPay){ double federal=totalPay*.22; double state =totalPay*.055; double netPay = totalPay - federal - state; federal =federal*Math.pow(10,2); federal =Math.round(federal); federal= federal/Math.pow(10,2); state =state*Math.pow(10,2); state =Math.round(state); state= state/Math.pow(10,2); totalPay =totalPay*Math.pow(10,2); totalPay =Math.round(totalPay); totalPay= totalPay/Math.pow(10,2); netPay =netPay*Math.pow(10,2); netPay =Math.round(netPay); netPay= netPay/Math.pow(10,2); System.out.printf("\nTotal Pay \t: %1$.2f.\n", totalPay); System.out.printf("State W/H \t: %1$.2f.\n", state); System.out.printf("Federal W/H : %1$.2f.\n", federal); System.out.printf("Net Pay \t: %1$.2f.\n", netPay); return totalPay; } public static double officeCalc(double officeRate,double officeHours){ double overtime=0; if (officeHours>=40) overtime = officeHours-40; else overtime = 0; if (officeHours >= 40) officeHours = 40; double otRate = officeRate * 1.5; double totalPay= (officeRate * officeHours) + (otRate*overtime); return totalPay; } public static double factoryCalc(double widgets){ double totalPay=widgets*.35 +300; return totalPay; } public static double salesCalc(double totalSales){ double totalPay = totalSales * .05 + 500; return totalPay; } }

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• Linked Lists in Java - Help with assignment

  - by doron2010

  I have been trying to solve this assignment all day, please help me. I'm completely lost. 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 : (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 char charAt (int i) - returns the char in the place i in the string. Assume that the value of i is in the right range. public StringList concat (String str) - returns a string that consists of the string that it is operated on and in its end the string "str" is concatenated. 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. public int indexOf (int ch, int fromIndex) - returns the index in the string it is operated on of the first appeareance of the char "ch", as the search begins in the index "fromIndex". If the char "ch" doesn't appear in the string, returns -1. public boolean equals (String str) - returns true if the string that it is operated on is equal to the string str. Otherwise returns false. This method must be written in recursion, without using loops at all. public int compareTo (String str) - compares between the string that the method is operated on to the string "str" that is in the parameter. The method returns 0 if the strings are equal. If the string in the object is smaller lexicographic from the string "str" in the paramater, a negative number will be returned. And if the string in the object is bigger lexicographic from the string "str", a positive number will be returned. public StringList substring (int i) - returns the list of the substring that starts in the place i in the string on which it operates. Meaning, the sub-string from the place i until the end of the string. Assume the value of i is in the right range. public StringList substring (int i, int j) - returns the list of the substring that begins in the place i and ends in the place j (not included) in the string it operates on. Assume the values of i, j are in the right range. public int length() - will return the length of the string on which it operates. 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.

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• Termite colony simulator using java

  - by ashii

  hi everyone, i hve to design a simulator that will maintain an environment, which consists of a collection of patches arranged in a rectangular grid of arbitrary size. Each patch contains zero or more wood chips. A patch may be occupied by one or more termites or predators, which are mobile entities that live within the world and behave according to simple rules. A TERMITE can pick up a wood chip from the patch that it is currently on, or drop a wood chip that it is carrying. Termites travel around the grid by moving randomly from their current patch to a neighbouring patch, in one of four possible directions. New termites may hatch from eggs, and this is simulated by the appearance of a new termite at a random patch within the environment. A PREDATOR moves in a similar way to termites, and if a predator moves onto a patch that is occupied by a termite, then the predator eats the termite. At initialization, the termites, predators, and wood chips are distributed randomly in the environment. Simulation then proceeds in a loop, and the new state of the environment is obtained at each iteration. i have designed the arena using jpanel but im not able to randomnly place wood,termite and predator in that arena. can any one help me out?? my code for the arena is as following: 01 import java.awt.*; 02 import javax.swing.*; 03 04 public class Arena extends JPanel 05 { 06 private static final int Rows = 8; 07 private static final int Cols = 8; 08 public void paint(Graphics g) 09 { 10 Dimension d = this.getSize(); 11 // don't draw both sets of squares, when you can draw one 12 // fill in the entire thing with one color 13 g.setColor(Color.WHITE); 14 // make the background 15 g.fillRect(0,0,d.width,d.height); 16 // draw only black 17 g.setColor(Color.BLACK); 18 // pick a square size based on the smallest dimension 19 int sqsize = ((d.width<d.height) ? d.width/Cols : d.height/Rows); 20 // loop for rows 21 for (int row=0; row<Rows; row++) 22 { 23 int y = row*sqsize; // y stays same for entire row, set here 24 int x = (row%2)*sqsize; // x starts at 0 or one square in 25 for (int i=0; i<Cols/2; i++) 26 { 27 // you will only be drawing half the squares per row 28 // draw square 29 g.fillRect(x,y,sqsize,sqsize); 30 // move two square sizes over 31 x += sqsize*2; 32 } 33 } 34 35 } 36 37 38 39 public void update(Graphics g) { paint(g); } 40 41 42 43 public static void main (String[] args) 44 { 45 46 JFrame frame = new JFrame("Arena"); 47 frame.setSize(600,400); 48 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 49 frame.setContentPane(new Arena()); 50 frame.setVisible(true); 51 } 52 53 }

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