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  • C++ Program Flow: Sockets in an Object and the Main Function

    - by jfm429
    I have a rather tricky problem regarding C++ program flow using sockets. Basically what I have is this: a simple command-line socket server program that listens on a socket and accepts one connection at a time. When that connection is lost it opens up for further connections. That socket communication system is contained in a class. The class is fully capable of receiving the connections and mirroring the data received to the client. However, the class uses UNIX sockets, which are not object-oriented. My problem is that in my main() function, I have one line - the one that creates an instance of that object. The object then initializes and waits. But as soon as a connection is gained, the object's initialization function returns, and when that happens, the program quits. How do I somehow wait until this object is deleted before the program quits? Summary: main() creates instance of object Object listens Connection received Object's initialization function returns main() exits (!) What I want is for main() to somehow delay until that object is finished with what it's doing (aka it will delete itself) before it quits. Any thoughts?

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  • IOException during blocking network NIO in JDK 1.7

    - by Bass
    I'm just learning NIO, and here's the short example I've written to test how a blocking NIO can be interrupted: class TestBlockingNio { private static final boolean INTERRUPT_VIA_THREAD_INTERRUPT = true; /** * Prevent the socket from being GC'ed */ static Socket socket; private static SocketChannel connect(final int port) { while (true) { try { final SocketChannel channel = SocketChannel.open(new InetSocketAddress(port)); channel.configureBlocking(true); return channel; } catch (final IOException ioe) { try { Thread.sleep(1000); } catch (final InterruptedException ie) { } continue; } } } private static byte[] newBuffer(final int length) { final byte buffer[] = new byte[length]; for (int i = 0; i < length; i++) { buffer[i] = (byte) 'A'; } return buffer; } public static void main(final String args[]) throws IOException, InterruptedException { final int portNumber = 10000; new Thread("Reader") { public void run() { try { final ServerSocket serverSocket = new ServerSocket(portNumber); socket = serverSocket.accept(); /* * Fully ignore any input from the socket */ } catch (final IOException ioe) { ioe.printStackTrace(); } } }.start(); final SocketChannel channel = connect(portNumber); final Thread main = Thread.currentThread(); final Thread interruptor = new Thread("Inerruptor") { public void run() { System.out.println("Press Enter to interrupt I/O "); while (true) { try { System.in.read(); } catch (final IOException ioe) { ioe.printStackTrace(); } System.out.println("Interrupting..."); if (INTERRUPT_VIA_THREAD_INTERRUPT) { main.interrupt(); } else { try { channel.close(); } catch (final IOException ioe) { System.out.println(ioe.getMessage()); } } } } }; interruptor.setDaemon(true); interruptor.start(); final ByteBuffer buffer = ByteBuffer.allocate(32768); int i = 0; try { while (true) { buffer.clear(); buffer.put(newBuffer(buffer.capacity())); buffer.flip(); channel.write(buffer); System.out.print('X'); if (++i % 80 == 0) { System.out.println(); Thread.sleep(100); } } } catch (final ClosedByInterruptException cbie) { System.out.println("Closed via Thread.interrupt()"); } catch (final AsynchronousCloseException ace) { System.out.println("Closed via Channel.close()"); } } } In the above example, I'm writing to a SocketChannel, but noone is reading from the other side, so eventually the write operation hangs. This example works great when run by JDK-1.6, with the following output: Press Enter to interrupt I/O XXXX Interrupting... Closed via Thread.interrupt() — meaning that only 128k of data was written to the TCP socket's buffer. When run by JDK-1.7 (1.7.0_25-b15 and 1.7.0-u40-b37), however, the very same code bails out with an IOException: Press Enter to interrupt I/O XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXX Exception in thread "main" java.io.IOException: Broken pipe at sun.nio.ch.FileDispatcherImpl.write0(Native Method) at sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:47) at sun.nio.ch.IOUtil.writeFromNativeBuffer(IOUtil.java:93) at sun.nio.ch.IOUtil.write(IOUtil.java:65) at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:487) at com.example.TestBlockingNio.main(TestBlockingNio.java:109) Can anyone explain this different behaviour?

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  • Object validator - is this good design?

    - by neo2862
    I'm working on a project where the API methods I write have to return different "views" of domain objects, like this: namespace View.Product { public class SearchResult : View { public string Name { get; set; } public decimal Price { get; set; } } public class Profile : View { public string Name { get; set; } public decimal Price { get; set; } [UseValidationRuleset("FreeText")] public string Description { get; set; } [SuppressValidation] public string Comment { get; set; } } } These are also the arguments of setter methods in the API which have to be validated before storing them in the DB. I wrote an object validator that lets the user define validation rulesets in an XML file and checks if an object conforms to those rules: [Validatable] public class View { [SuppressValidation] public ValidationError[] ValidationErrors { get { return Validator.Validate(this); } } } public static class Validator { private static Dictionary<string, Ruleset> Rulesets; static Validator() { // read rulesets from xml } public static ValidationError[] Validate(object obj) { // check if obj is decorated with ValidatableAttribute // if not, return an empty array (successful validation) // iterate over the properties of obj // - if the property is decorated with SuppressValidationAttribute, // continue // - if it is decorated with UseValidationRulesetAttribute, // use the ruleset specified to call // Validate(object value, string rulesetName, string FieldName) // - otherwise, get the name of the property using reflection and // use that as the ruleset name } private static List<ValidationError> Validate(object obj, string fieldName, string rulesetName) { // check if the ruleset exists, if not, throw exception // call the ruleset's Validate method and return the results } } public class Ruleset { public Type Type { get; set; } public Rule[] Rules { get; set; } public List<ValidationError> Validate(object property, string propertyName) { // check if property is of type Type // if not, throw exception // iterate over the Rules and call their Validate methods // return a list of their return values } } public abstract class Rule { public Type Type { get; protected set; } public abstract ValidationError Validate(object value, string propertyName); } public class StringRegexRule : Rule { public string Regex { get; set; } public StringRegexRule() { Type = typeof(string); } public override ValidationError Validate(object value, string propertyName) { // see if Regex matches value and return // null or a ValidationError } } Phew... Thanks for reading all of this. I've already implemented it and it works nicely, and I'm planning to extend it to validate the contents of IEnumerable fields and other fields that are Validatable. What I'm particularly concerned about is that if no ruleset is specified, the validator tries to use the name of the property as the ruleset name. (If you don't want that behavior, you can use [SuppressValidation].) This makes the code much less cluttered (no need to use [UseValidationRuleset("something")] on every single property) but it somehow doesn't feel right. I can't decide if it's awful or awesome. What do you think? Any suggestions on the other parts of this design are welcome too. I'm not very experienced and I'm grateful for any help. Also, is "Validatable" a good name? To me, it sounds pretty weird but I'm not a native English speaker.

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  • Why I get this error in CXF

    - by Milan
    I want to make dynamic web service invoker in JSF with CXF. But when I load this simple code I get error. The code: JaxWsDynamicClientFactory dcf = JaxWsDynamicClientFactory.newInstance(); Client client = dcf.createClient("http://ws.strikeiron.com/IPLookup2?wsdl"); The error: No Factories configured for this Application. This happens if the faces-initialization does not work at all - make sure that you properly include all configuration settings necessary for a basic faces application and that all the necessary libs are included. Also check the logging output of your web application and your container for any exceptions! If you did that and find nothing, the mistake might be due to the fact that you use some special web-containers which do not support registering context-listeners via TLD files and a context listener is not setup in your web.xml. A typical config looks like this; org.apache.myfaces.webapp.StartupServletContextListener Caused by: java.lang.IllegalStateException - No Factories configured for this Application. This happens if the faces-initialization does not work at all - make sure that you properly include all configuration settings necessary for a basic faces application and that all the necessary libs are included. Also check the logging output of your web application and your container for any exceptions! If you did that and find nothing, the mistake might be due to the fact that you use some special web-containers which do not support registering context-listeners via TLD files and a context listener is not setup in your web.xml. A typical config looks like this; org.apache.myfaces.webapp.StartupServletContextListener Any Idea how to solve the problem?

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  • A trivial Python SWIG error question

    - by Alex
    I am trying to get Python running with swig to do C/C++. I am running the tutorial here, 'building a python module'. When I do the call gcc -c example.c example_wrap.c -I /my_correct_path/python2.5 I get an error: my_correct_path/python2.5/pyport.h:761:2: error: #error "LONG_BIT definition appears wrong for platform (bad gcc/glibc config?)." example_wrap.c: In function 'SWIG_Python_ConvertFunctionPtr': example_wrap.c:2034: warning: initialization discards qualifiers from pointer target type example_wrap.c: In function 'SWIG_Python_FixMethods': example_wrap.c:3232: warning: initialization discards qualifiers from pointer target type It actually does create an example.o file, but it doesn't work. I am using python2.5 not 2.1 as in the example, is this a problem? The error (everything else is just a 'warning') says something about wrong platform. This is a 64bit machine; is this a problem? Is my gcc configured wrong for my machine? How do I get past this? UPDATE: I am still having problems. How do I actually implement this "fix"?

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  • How to generate a random unique string with more than 2^30 combination. I also wanted to reverse the process. Is this possible?

    - by Yusuf S
    I have a string which contains 3 elements: a 3 digit code (example: SIN, ABD, SMS, etc) a 1 digit code type (example: 1, 2, 3, etc) a 3 digit number (example: 500, 123, 345) Example string: SIN1500, ABD2123, SMS3345, etc.. I wanted to generate a UNIQUE 10 digit alphanumeric and case sensitive string (only 0-9/a-z/A-Z is allowed), with more than 2^30 (about 1 billion) unique combination per string supplied. The generated code must have a particular algorithm so that I can reverse the process. For example: public static void main(String[] args) { String test = "ABD2123"; String result = generateData(test); System.out.println(generateOutput(test)); //for example, the output of this is: 1jS8g4GDn0 System.out.println(generateOutput(result)); //the output of this will be ABD2123 (the original string supplied) } What I wanted to ask is is there any ideas/examples/libraries in java that can do this? Or at least any hint on what keyword should I put on Google? I tried googling using the keyword java checksum, rng, security, random number, etc and also tried looking at some random number solution (java SecureRandom, xorshift RNG, java.util.zip's checksum, etc) but I can't seem to find one? Thanks! EDIT: My use case for this program is to generate some kind of unique voucher number to be used by specific customers. The string supplied will contains 3 digit code for company ID, 1 digit code for voucher type, and a 3 digit number for the voucher nominal. I also tried adding 3 random alphanumeric (so the final digit is 7 + 3 digit = 10 digit). This is what I've done so far, but the result is not very good (only about 100 thousand combination): public static String in ="somerandomstrings"; public static String out="someotherrandomstrings"; public static String encrypt(String kata) throws Exception { String result=""; String ina=in; String outa=out; Random ran = new Random(); Integer modulus=in.length(); Integer offset= ((Integer.parseInt(Utils.convertDateToString(new Date(), "SS")))+ran.nextInt(60))/2%modulus; result=ina.substring(offset, offset+1); ina=ina+ina; ina=ina.substring(offset, offset+modulus); result=result+translate(kata, ina, outa); return result; } EDIT: I'm sorry I forgot to put the "translate" function : public static String translate(String kata,String seq1, String seq2){ String result=""; if(kata!=null&seq1!=null&seq2!=null){ String[] a=kata.split(""); for (int j = 1; j < a.length; j++) { String b=a[j]; String[]seq1split=seq1.split(""); String[]seq2split=seq2.split(""); int hint=seq1.indexOf(b)+1; String sq=""; if(seq1split.length>hint) sq=seq1split[hint]; String sq1=""; if(seq2split.length>hint) sq1=seq2split[hint]; b=b.replace(sq, sq1); result=result+b; } } return result; }

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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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  • Mbean registered but not found in mbean Server

    - by Prisco
    I have a problem about the mbeans. I have created a simple mbean and I have registered it on the default mBeanServer that is run (Via eclipse or java -jar mbean.jar) and in the same process if I try to fouund the mbean registered with a simple query: for (ObjectInstance instance : mbs.queryMBeans(ObjectNameMbean, null)) { System.out.println(instance.toString()); } the query retuerns my mbean, but if I start another process and try to search this mbean registered the mbeas is not found! why? The approch is : (Process that is running) public static void main(String[] args) throws Exception { MBeanServer mbeanServer =ManagementFactory.getPlatformMBeanServer(); ObjectName objectName = new ObjectName(ObjectNameMbean); Simple simple = new Simple (1, 0); mbeanServer.registerMBean(simple, objectName); while (true) { wait (Is this necessary?) } } So this is the first process that is running (that has the only pourpose to registry the mbean, because there is another process that want to read these informations. So I start another process to search this mbean but nothing. I 'm not using jboss but the local Java virtual Machine but my scope is to deploy this simple application in one ejb (autostart) and another ejb will read all informations. All suggestions are really apprecciated. This example should be more useful : Object Hello: public class Hello implements HelloMBean { public void sayHello() { System.out.println("hello, world"); } public int add(int x, int y) { return x + y; } public String getName() { return this.name; } public int getCacheSize() { return this.cacheSize; } public synchronized void setCacheSize(int size) { this.cacheSize = size; System.out.println("Cache size now " + this.cacheSize); } private final String name = "Reginald"; private int cacheSize = DEFAULT_CACHE_SIZE; private static final int DEFAULT_CACHE_SIZE = 200; } Interface HelloBean (implemented by Hello) public interface HelloMBean { public void sayHello(); public int add(int x, int y); public String getName(); public int getCacheSize(); public void setCacheSize(int size); } Simple Main import java.lang.management.ManagementFactory; import java.util.logging.Logger; import javax.management.MBeanServer; import javax.management.ObjectName; public class Main { static Logger aLog = Logger.getLogger("MBeanTest"); public static void main(String[] args) { try{ MBeanServer mbs = ManagementFactory.getPlatformMBeanServer(); ObjectName name = new ObjectName("ApplicationDomain:type=Hello"); Hello mbean = new Hello(); mbs.registerMBean(mbean, name); // System.out.println(mbs.getAttribute(name, "Name")); aLog.info("Waiting forever..."); Thread.sleep(Long.MAX_VALUE); } catch(Exception x){ x.printStackTrace(); aLog.info("exception"); } } } So now I have exported this project as jar file and run it as "java -jar helloBean.jar" and by eclipse I have modified the main class to read informations of this read (Example "Name" attribute) by using the same objectname used to registry it . Main to read : public static void main(String[] args) { try{ MBeanServer mbs = ManagementFactory.getPlatformMBeanServer(); ObjectName name = new ObjectName("ApplicationDomain:type=Hello"); System.out.println(mbs.getAttribute(name, "Name")); } catch(Exception x){ x.printStackTrace(); aLog.info("exception"); } } But nothing, the bean is not found.

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  • Dynamically loading external HTML in a div using Java Script

    - by user354051
    I have prepared some demo examples for the topic. There is page name "changelog.html" here: http://pantheon-studios.in/test/jquery/changelog.html This is working fine if loaded directly. I am trying to load this page dynamically into: http://pantheon-studios.in/test/jquery/index.html Here changelog.html doesn't behaving as expected. I think the init script on changelog.html is not getting executed or something else is happening when loading it dynamically. Like wise I do have couple of other pages using various jQuery and other java scripts plugins. Some of those needs initialization like animatedcollapse.js in the above example, and couple of them doesn't need initialization, you can directly call the script and go. I also gave a try using: jQuery.getScript("anim.js") after dynamically loading "changelog.html" but doesn't work. The "anim.js" contains animatedcollapse.addDiv('cat', 'fade=0,speed=400,group=pets,hide=1'); animatedcollapse.addDiv('dog', 'fade=0,speed=400,group=pets,hide=1'); animatedcollapse.addDiv('rabbit', 'fade=0,speed=400,group=pets,hide=1'); animatedcollapse.init(); I would really appreciate is some one point me out the right direction. I am completely new to web programming so please have some patience with me. Thanks

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  • Not getting key value from Identity column back after inserting new row with SubSonic ActiveRecord

    - by mikedevenney
    I'm sure I'm missing the obvious answer here, but could use a hand. I'm new to SubSonic and using version 3. I've got myself to the point of being able to query and insert, but I'm stuck with how I would get the value of the identity column back after my insert. I saw another post that mentioned Linq Templates. I'm not using those (at least I don't think I am...?) TIA ... UPDATE ... So I've been debugging through my code watching how the SubSonic code works and I found where the indentity column is being ignored. I use int as the datatype for my ID columns in the database and set them as identity. Since int is a non-nullable data type in c# the logical test in the Add method (public void Add(IDataProvider provider)) that checks if there is a value in the key column by doing a (key==null) could be the issue. The code that gets the new value for the identity field is in the 'true path', since an int can't be null and I use ints as my identity column data types this test will never pass. The ID field for my object has a 0 in it that I didn't put there. I assume it's set during the initialization of the object. Am I off base here? Is the answer to change my data types in the database? Another question (more a curiosity). I noticed that some of the properties in the generated classes are declared with a ? after the datatype. I'm not familiar with this declaration construct... what gives? There are some declared as an int (non key fields) and others that are declared as int? (key fields). Does this have something to do with how they're treated at initialization? Any help is appreciated! --BUMP--

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  • Java calendar day_of_week not working

    - by Raptrex
    I have a for loop starting at startTime going up to endTime and I would like it to print out the date if it is either a monday, tuesday, wednesday, thursday, or friday. Currently, it is only printing out the endTime date. The other stuff splits the string, which you can ignore. Since 5/16/2010 is a sunday, it should print out 17,18,19,20,21, 24 and 25. However it only prints 25 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++) { 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) { startCal.set(Calendar.DATE, i); System.out.println(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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  • How to manage lifecycle in a ViewGroup-derived class?

    - by Scott Smith
    I had a bunch of code in an activity that displays a running graph of some external data. As the activity code was getting kind of cluttered, I decided to extract this code and create a GraphView class: public class GraphView extends LinearLayout { public GraphView(Context context, AttributeSet attrs) { super(context, attrs); LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); inflater.inflate(R.layout.graph_view, this, true); } public void start() { // Perform initialization (bindings, timers, etc) here } public void stop() { // Unbind, destroy timers, yadda yadda } . . . } Moving stuff into this new LinearLayout-derived class was simple. But there was some lifecycle management code associated with creating and destroying timers and event listeners used by this graph (I didn't want this thing polling in the background if the activity was paused, for example). Coming from a MS Windows background, I kind of expected to find overridable onCreate() and onDestroy() methods or something similar, but I haven't found anything of the sort in LinearLayout (or any of its inherited members). Having to leave all of this initialization code in the Activity, and then having to pass it into the view seemed like it defeated the original purpose of encapsulating all of this code into a reusable view. I ended up adding two additional public methods to my view: start() and stop(). I make these calls from the activity's onResume() and onPause() methods respectively. This seems to work, but it feels like I'm using duct tape here. Does anyone know how this is typically done? I feel like I'm missing something...

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  • C# IOException: The process cannot access the file because it is being used by another process.

    - by Michiel Bester
    Hi, I have a slight problem. What my application is supose to do, is to watch a folder for any newly copied file with the extention '.XSD' open the file and assign the lines to an array. After that the data from the array should be inserted into a MySQL database, then move the used file to another folder if it's done. The problem is that the application works fine with the first file, but as soon as the next file is copied to the folder I get this exception for example: 'The process cannot access the file 'C:\inetpub\admission\file2.XPD' because it is being used by another process'. If two files on the onther hand is copied at the same time there's no problem at all. The following code is on the main window: public partial class Form1 : Form { static string folder = specified path; static FileProcessor processor; public Form1() { InitializeComponent(); processor = new FileProcessor(); InitializeWatcher(); } static FileSystemWatcher watcher; static void InitializeWatcher() { watcher = new FileSystemWatcher(); watcher.Path = folder; watcher.Created += new FileSystemEventHandler(watcher_Created); watcher.EnableRaisingEvents = true; watcher.Filter = "*.XPD"; } static void watcher_Created(object sender, FileSystemEventArgs e) { processor.QueueInput(e.FullPath); } } As you can see the file's path is entered into a queue for processing which is on another class called FileProcessor: class FileProcessor { private Queue<string> workQueue; private Thread workerThread; private EventWaitHandle waitHandle; public FileProcessor() { workQueue = new Queue<string>(); waitHandle = new AutoResetEvent(true); } public void QueueInput(string filepath) { workQueue.Enqueue(filepath); if (workerThread == null) { workerThread = new Thread(new ThreadStart(Work)); workerThread.Start(); } else if (workerThread.ThreadState == ThreadState.WaitSleepJoin) { waitHandle.Set(); } } private void Work() { while (true) { string filepath = RetrieveFile(); if (filepath != null) ProcessFile(filepath); else waitHandle.WaitOne(); } } private string RetrieveFile() { if (workQueue.Count > 0) return workQueue.Dequeue(); else return null; } private void ProcessFile(string filepath) { string xName = Path.GetFileName(filepath); string fName = Path.GetFileNameWithoutExtension(filepath); string gfolder = specified path; bool fileInUse = true; string line; string[] itemArray = null; int i = 0; #region Declare Db variables //variables for each field of the database is created here #endregion #region Populate array while (fileInUse == true) { FileStream fs = new FileStream(filepath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite); StreamReader reader = new StreamReader(fs); itemArray = new string[75]; while (!reader.EndOfStream == true) { line = reader.ReadLine(); itemArray[i] = line; i++; } fs.Flush(); reader.Close(); reader.Dispose(); i = 0; fileInUse = false; } #endregion #region Assign Db variables //here all the variables get there values from the array #endregion #region MySql Connection //here the connection to mysql is made and the variables are inserted into the db #endregion #region Test and Move file if (System.IO.File.Exists(gfolder + xName)) { System.IO.File.Delete(gfolder + xName); } Directory.Move(filepath, gfolder + xName); #endregion } } The problem I get occurs in the Populate array region. I read alot of other threads and was lead to believe that by flushing the file stream would help... I am also thinking of adding a try..catch for if the file process was successful, the file is moved to gfolder and if it failed, moved to bfolder Any help would be awesome Tx

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  • clang does not compile but g++ does

    - by user1095108
    Can someone help me with this code: #include <type_traits> #include <vector> struct nonsense { }; template <struct nonsense const* ptr, typename R> typename std::enable_if<!std::is_void<R>::value, int>::type fo(void* const) { return 0; } template <struct nonsense const* ptr, typename R> typename std::enable_if<std::is_void<R>::value, int>::type fo(void* const) { return 1; } typedef int (*func_type)(void*); template <std::size_t O> void run_me() { static struct nonsense data; typedef std::pair<char const* const, func_type> pair_type; std::vector<pair_type> v; v.push_back(pair_type{ "a", fo<&data, int> }); v.push_back(pair_type{ "b", fo<&data, void> }); } int main(int, char*[]) { run_me<2>(); return 0; } clang-3.3 does not compile this code, but g++-4.8.1 does, which of the two compiler is right? Is something wrong with the code, as I suspect? The error reads: a.cpp:32:15: error: no matching constructor for initialization of 'pair_type' (aka 'pair<const char *const, func_type>') v.push_back(pair_type{ "a", fo<&data, int> }); ^ ~~~~~~~~~~~~~~~~~~~~~~~ a.cpp:33:15: error: no matching constructor for initialization of 'pair_type' (aka 'pair<const char *const, func_type>') v.push_back(pair_type{ "b", fo<&data, void> }); ^ ~~~~~~~~~~~~~~~~~~~~~~~~

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  • C# ambiguity in Func + extension methods + lambdas

    - by Hobbes
    I've been trying to make my way through this article: http://blogs.msdn.com/wesdyer/archive/2008/01/11/the-marvels-of-monads.aspx ... And something on page 1 made me uncomfortable. In particular, I was trying to wrap my head around the Compose<() function, and I wrote an example for myself. Consider the following two Func's: Func<double, double> addTenth = x => x + 0.10; Func<double, string> toPercentString = x => (x * 100.0).ToString() + "%"; No problem! It's easy to understand what these two do. Now, following the example from the article, you can write a generic extension method to compose these functions, like so: public static class ExtensionMethods { public static Func<TInput, TLastOutput> Compose<TInput, TFirstOutput, TLastOutput>( this Func<TFirstOutput, TLastOutput> toPercentString, Func<TInput, TFirstOutput> addTenth) { return input => toPercentString(addTenth(input)); } } Fine. So now you can say: string x = toPercentString.Compose<double, double, string>(addTenth)(0.4); And you get the string "50%" So far, so good. But there's something ambiguous here. Let's say you write another extension method, so now you have two functions: public static class ExtensionMethods { public static Func<TInput, TLastOutput> Compose<TInput, TFirstOutput, TLastOutput>( this Func<TFirstOutput, TLastOutput> toPercentString, Func<TInput, TFirstOutput> addTenth) { return input => toPercentString(addTenth(input)); } public static Func<double, string> Compose<TInput, TFirstOutput, TLastOutput>(this Func<double, string> toPercentString, Func<double, double> addTenth) { return input => toPercentString(addTenth(input + 99999)); } } Herein is the ambiguity. Don't these two function have overlapping signatures? Yes. Does this even compile? Yes. Which one get's called? The second one (which clearly gives you the "wrong" result) gets called. If you comment out either function, it still compiles, but you get different results. It seems like nitpicking, but there's something that deeply offends my sensibilities here, and I can't put my finger on it. Does it have to do with extension methods? Does it have to do with lambdas? Or does it have to do with how Func< allows you to parameterize the return type? I'm not sure. I'm guessing that this is all addressed somewhere in the spec, but I don't even know what to Google to find this. Help!

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  • SQL Compact performance on device

    - by Ben M
    My SQL Compact database is very simple, with just three tables and a single index on one of the tables (the table with 200k rows; the other two have less than a hundred each). The first time the .sdf file is used by my Compact Framework application on the target Windows Mobile device, the system hangs for well over a minute while "something" is done to the database: when deployed, the DB is 17 megabytes, and after this first usage, it balloons to 24 megs. All subsequent usage is pretty fast, so I'm assuming there's some sort of initialization / index building going on during this first usage. I'd rather not subject the user to this delay, so I'm wondering what this initialization process is and whether it can be performed before deployment. For now, I've copied the "initialized" database back to my desktop for use in the setup project, but I'd really like to have a better answer / solution. I've tried "full compact / repair" in the VS Database Properties dialog, but this made no difference. Any ideas? For the record, I should add that the database is only read from by the device application -- no modifications are made by that code.

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  • std::vector elements initializing

    - by Chameleon
    std::vector<int> v1(1000); std::vector<std::vector<int>> v2(1000); std::vector<std::vector<int>::const_iterator> v3(1000); How elements of these 3 vectors initialized? About int, I test it and I saw that all elements become 0. Is this standard? I believed that primitives remain undefined. I create a vector with 300000000 elements, give non-zero values, delete it and recreate it, to avoid OS memory clear for data safety. Elements of recreated vector were 0 too. What about iterator? Is there a initial value (0) for default constructor or initial value remains undefined? When I check this, iterators point to 0, but this can be OS When I create a special object to track constructors, I saw that for first object, vector run the default constructor and for all others it run the copy constructor. Is this standard? Is there a way to completely avoid initialization of elements? Or I must create my own vector? (Oh my God, I always say NOT ANOTHER VECTOR IMPLEMENTATION) I ask because I use ultra huge sparse matrices with parallel processing, so I cannot use push_back() and of course I don't want useless initialization, when later I will change the value.

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  • How can one enforce calling a base class function after derived class constructor?

    - by Mike Elkins
    I'm looking for a clean C++ idiom for the following situation: class SomeLibraryClass { public: SomeLibraryClass() { /* start initialization */ } void addFoo() { /* we are a collection of foos */ } void funcToCallAfterAllAddFoos() { /* Making sure this is called is the issue */ } }; class SomeUserClass : public SomeLibraryClass { public: SomeUserClass() { addFoo(); addFoo(); addFoo(); // SomeUserClass has three foos. } }; class SomeUserDerrivedClass : public SomeUserClass { public: SomeUserDerrivedClass() { addFoo(); // This one has four foos. } }; So, what I really want is for SomeLibraryClass to enforce the calling of funcToCallAfterAllAddFoos at the end of the construction process. The user can't put it at the end of SomeUserClass::SomeUserClass(), that would mess up SomeUserDerrivedClass. If he puts it at the end of SomeUserDerrivedClass, then it never gets called for SomeUserClass. To further clarify what I need, imagine that /* start initialization */ acquires a lock, and funcToCallAfterAllAddFoos() releases a lock. The compiler knows when all the initializations for an object are done, but can I get at that information by some nice trick?

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  • Why can't we just use a hash of passphrase as the encryption key (and IV) with symmetric encryption algorithms?

    - by TX_
    Inspired by my previous question, now I have a very interesting idea: Do you really ever need to use Rfc2898DeriveBytes or similar classes to "securely derive" the encryption key and initialization vector from the passphrase string, or will just a simple hash of that string work equally well as a key/IV, when encrypting the data with symmetric algorithm (e.g. AES, DES, etc.)? I see tons of AES encryption code snippets, where Rfc2898DeriveBytes class is used to derive the encryption key and initialization vector (IV) from the password string. It is assumed that one should use a random salt and a shitload of iterations to derive secure enough key/IV for the encryption. While deriving bytes from password string using this method is quite useful in some scenarios, I think that's not applicable when encrypting data with symmetric algorithms! Here is why: using salt makes sense when there is a possibility to build precalculated rainbow tables, and when attacker gets his hands on hash he looks up the original password as a result. But... with symmetric data encryption, I think this is not required, as the hash of password string, or the encryption key, is never stored anywhere. So, if we just get the SHA1 hash of password, and use it as the encryption key/IV, isn't that going to be equally secure? What is the purpose of using Rfc2898DeriveBytes class to generate key/IV from password string (which is a very very performance-intensive operation), when we could just use a SHA1 (or any other) hash of that password? Hash would result in random bit distribution in a key (as opposed to using string bytes directly). And attacker would have to brute-force the whole range of key (e.g. if key length is 256bit he would have to try 2^256 combinations) anyway. So either I'm wrong in a dangerous way, or all those samples of AES encryption (including many upvoted answers here at SO), etc. that use Rfc2898DeriveBytes method to generate encryption key and IV are just wrong.

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  • pass arraylist bean from android to webservice php

    - by user1547432
    i'm newbie in android with web service i'm trying to pass arraylist from android to webservice php server here's my bean code: public class ExpressionBean { public static final String EXPRESSION_ID = "expressionID"; public static final String EXPRESSION_TEXT = "expressionText"; public static final String ANS_TEXT1 = "ansText1"; public static final String ANS_TEXT2 = "ansText2"; public static final String ASSESSEE_ANSWER = "assesseeAnswer"; private String expressionID; private String expressionText; private String ansText1; private String ansText2; private String assesseeAnswer; public String getExpressionID() { return expressionID; } public void setExpressionID(String expressionID) { this.expressionID = expressionID; } public String getExpressionText() { return expressionText; } public void setExpressionText(String expressionText) { this.expressionText = expressionText; } public String getAnsText1() { return ansText1; } public void setAnsText1(String ansText1) { this.ansText1 = ansText1; } public String getAnsText2() { return ansText2; } public void setAnsText2(String ansText2) { this.ansText2 = ansText2; } public String getAssesseeAnswer() { return assesseeAnswer; } public void setAssesseeAnswer(String assesseeAnswer) { this.assesseeAnswer = assesseeAnswer; } } and here's my doInBackround on async task : protected Boolean doInBackground(Void... params) { // TODO: attempt authentication against a network service. boolean result = false; // test = new TestBean(); // int resultTest = 0; UserFunctions userFunction = new UserFunctions(); Log.d(TAG, "UID : " + mEmail); // Log.d(TAG, "resultTest : " + resultTest); JSONObject jsonTest = userFunction.storeTest(mEmail); Log.d(TAG, "After JSON TEST "); try { if (jsonTest.getString(KEY_SUCCESS) != null) { String res = jsonTest.getString(KEY_SUCCESS); JSONObject testData = jsonTest.getJSONObject(TAG_TEST); test = new TestBean(); test.setTestid(testData.getInt(TAG_TEST_ID)); test.setUid(testData.getInt(TAG_UID)); JSONArray list = new JSONArray(); String list2; for (int position = 0; position < expressionList.size(); position++) { Gson gson = new Gson(); list.put(gson.toJson(expressionList.get(position))); } Log.d(TAG, "JSONArray list coy : " + list); UserFunctions uf = new UserFunctions(); JSONObject jsonHistoryList = new JSONObject(); jsonHistoryList = uf.storeHistoryList(list.toString()); if (Integer.parseInt(res) == 1) { result = true; finish(); } else { result = false; } } } catch (JSONException e) { e.printStackTrace(); return false; } // TODO: register the new account here. return result; } and here's storeHistoryList Method : public JSONObject storeHistoryList(String list) { // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("tag", storeHistory_tag)); params.add(new BasicNameValuePair("list", list)); JSONObject json = jsonParser.getJSONFromUrl(URL, params); return json; } i want to pass list to web service list is an arraylist ExpressionBean i used gson for convert bean to json but when i execute, the log said "error parsing data... jsonarray cannot be converted to jsonobject what i must to do? thanks

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  • Strange compilation error on reference passing argument to function

    - by Grewdrewgoo Goobergabbsoen
    Here's the code: #include <iostream> using namespace std; void mysize(int &size, int size2); int main() { int *p; int val; p = &val; cout << p; mysize(&val, 20); // Error is pointed here! } void mysize(int &size, int size2) { cout << sizeof(size); size2 = size2 + 6000; cout << size2; } Here's the error output from GCC: In function 'int main()': Line 10: error: invalid initialization of non-const reference of type 'int&' from a temporary of type 'int*' compilation terminated due to -Wfatal-errors. What does that imply? I do not understand the error message ... invalid initialization of a non-constant? I declared the prototype function above with two parameters to take, one a reference of an integer and one just an integer value itself. I passed the reference of the int (see line 10), yet this error keeps being thrown at me. What is the issue?

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  • How to implement the disposable pattern in a class that inherits from another disposable class?

    - by TheRHCP
    Hi, I often used the disposable pattern in simple classes that referenced small amount of resources, but I never had to implement this pattern on a class that inherits from another disposable class and I am starting to be a bit confused in how to free the whole resources. I start with a little sample code: public class Tracer : IDisposable { bool disposed; FileStream fileStream; public Tracer() { //Some fileStream initialization } public void Dispose() { this.Dispose(true); GC.SuppressFinalize(this); } protected virtual void Dispose(bool disposing) { if (!disposed) { if (disposing) { if (fileStream != null) { fileStream.Dispose(); } } disposed = true; } } } public class ServiceWrapper : Tracer { bool disposed; ServiceHost serviceHost; //Some properties public ServiceWrapper () { //Some serviceHost initialization } //protected override void Dispose(bool disposing) //{ // if (!disposed) // { // if (disposing) // { // if (serviceHost != null) // { // serviceHost.Close(); // } // } // disposed = true; // } //} } My real question is: how to implement the disposable pattern inside my ServiceWrapper class to be sure that when I will dispose an instance of it, it will dispose resources in both inherited and base class? Thanks.

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  • Strange code behaviour?

    - by goldenmean
    Hi, I have a C code in which i have a structure declaration which has an array of int[576] declared in it. For some reason, i had to remove this array from the structure, So i replaced this array with a pointer as int *ptr; declared some global array of same type, somewhere else in the code, and initialized this pointer by assigning the global array to this pointer. So i did not have to change the way i was accessing this array, from other parts of my code. But it works fine/gives desired output when i have the array declared in the structure, but it gives junk output when i declare it as a pointer in the structure and assign a global array to this pointer, as a part of the pointer initialization. All this code is being run on MS-VC 6.0/Windows setup/Intel-x86. I tried below things: 1)Suspected structure padding/alignment but could not get any leads? If at all structure alignment could be a culprit how can i proceed to narrow it down and confirm it? 2) I have made sure that in both cases the array is initialized to some default values, say 0 before its first use, and its not being used before initialization. 3)I tried using global array as well as malloc based memory for this newly declared array. Same result, junk output. Am i missing something? How can i zero down the problem. Any pointers would be helpful. Thanks, -AD.

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  • Initializing an object to all zeroes

    - by dash-tom-bang
    Oftentimes data structures' valid initialization is to set all members to zero. Even when programming in C++, one may need to interface with an external API for which this is the case. Is there any practical difference between: some_struct s; memset(s, 0, sizeof(s)); and simply some_struct s = { 0 }; Do folks find themselves using both, with a method for choosing which is more appropriate for a given application? For myself, as mostly a C++ programmer who doesn't use memset much, I'm never certain of the function signature so I find the second example is just easier to use in addition to being less typing, more compact, and maybe even more obvious since it says "this object is initialized to zero" right in the declaration rather than waiting for the next line of code and seeing, "oh, this object is zero initialized." When creating classes and structs in C++ I tend to use initialization lists; I'm curious about folks thoughts on the two "C style" initializations above rather than a comparison against what is available in C++ since I suspect many of us interface with C libraries even if we code mostly in C++ ourselves.

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  • Doesn't get the output in Java Database Connectivity

    - by Dooree
    I'm working on Java Database Connectivity through Eclipse IDE. I built a database through Ubuntu Terminal, and I need to connect and work with it. However, when I tried to run the following code, I don't get any error, but the following output is showed, anybody knows why I don't get the output from the code ? //STEP 1. Import required packages import java.sql.*; public class FirstExample { // JDBC driver name and database URL static final String JDBC_DRIVER = "com.mysql.jdbc.Driver"; static final String DB_URL = "jdbc:mysql://localhost/EMP"; // Database credentials static final String USER = "username"; static final String PASS = "password"; public static void main(String[] args) { Connection conn = null; Statement stmt = null; try{ //STEP 2: Register JDBC driver Class.forName("com.mysql.jdbc.Driver"); //STEP 3: Open a connection System.out.println("Connecting to database..."); conn = DriverManager.getConnection(DB_URL,USER,PASS); //STEP 4: Execute a query System.out.println("Creating statement..."); stmt = conn.createStatement(); String sql; sql = "SELECT id, first, last, age FROM Employees"; ResultSet rs = stmt.executeQuery(sql); //STEP 5: Extract data from result set while(rs.next()){ //Retrieve by column name int id = rs.getInt("id"); int age = rs.getInt("age"); String first = rs.getString("first"); String last = rs.getString("last"); //Display values System.out.print("ID: " + id); System.out.print(", Age: " + age); System.out.print(", First: " + first); System.out.println(", Last: " + last); } //STEP 6: Clean-up environment rs.close(); stmt.close(); conn.close(); }catch(SQLException se){ //Handle errors for JDBC se.printStackTrace(); }catch(Exception e){ //Handle errors for Class.forName e.printStackTrace(); }finally{ //finally block used to close resources try{ if(stmt!=null) stmt.close(); }catch(SQLException se2){ }// nothing we can do try{ if(conn!=null) conn.close(); }catch(SQLException se){ se.printStackTrace(); }//end finally try }//end try System.out.println("Goodbye!"); }//end main }//end FirstExample <ConnectionProperties> <PropertyCategory name="Connection/Authentication"> <Property name="user" required="No" default="" sortOrder="-2147483647" since="all"> The user to connect as </Property> <Property name="password" required="No" default="" sortOrder="-2147483646" since="all"> The password to use when connecting </Property> <Property name="socketFactory" required="No" default="com.mysql.jdbc.StandardSocketFactory" sortOrder="4" since="3.0.3"> The name of the class that the driver should use for creating socket connections to the server. This class must implement the interface 'com.mysql.jdbc.SocketFactory' and have public no-args constructor. </Property> <Property name="connectTimeout" required="No" default="0" sortOrder="9" since="3.0.1"> Timeout for socket connect (in milliseconds), with 0 being no timeout. Only works on JDK-1.4 or newer. Defaults to '0'. </Property> ...

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