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  • Java - Problem in JTree

    - by Yatendra Goel
    There are 2 JTree: JTree1 and JTree2. Note that the nodes (country, city, colors, blue ...) all will be implemented as JCheckboxes so that user can select particular colors for each city or for the whole country by selecting their corresponding checkboxes. Problems: Q1. I want that each country or city can have its own colors selected. Means if a user wants city1.1 to have colors blue and violet and city2.1 to have colors red, then he first have to select the city1.1 checkbox and then select blue and violet, and after that when he selects city2.1, then the checkboxes blue and violet are deselected automatically so that user can select the colors for city2.1. But when the user selects the city1.1 again, then the JTree2should show the selected colors (bule and violet) for city1.1. So for this purpose, Is the JTree (with its nodes as checkboxes) correct option to implement or I should use some other JComponent? If JTree is a correct option, then how can I remember the colors of each city?

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  • Java HTTP Requests Buffer size

    - by behrk2
    Hello, I have an HTTP Request Dispatcher class that works most of the time, but I had noticed that it "stalls" when receiving larger requests. After looking into the problem, I thought that perhaps I wasn't allocating enough bytes to the buffer. Before, I was doing: byte[] buffer = new byte[10000]; After changing it to 20000, it seems to have stopped stalling: String contentType = connection.getHeaderField("Content-type"); ByteArrayOutputStream baos = new ByteArrayOutputStream(); InputStream responseData = connection.openInputStream(); byte[] buffer = new byte[20000]; int bytesRead = responseData.read(buffer); while (bytesRead > 0) { baos.write(buffer, 0, bytesRead); bytesRead = responseData.read(buffer); } baos.close(); connection.close(); Am I doing this right? Is there anyway that I can dynamically set the number of bytes for the buffer based on the size of the request? Thanks...

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  • Some more multitasking java issues

    - by owca
    I had a task to write simple game simulating two players picking up 1-3 matches one after another until the pile is gone. I managed to do it for computer choosing random value of matches but now I'd like to go further and allow humans to play the game. Here's what I already have : http://paste.pocoo.org/show/200660/ Class Player is a computer player, and PlayerMan should be human being. Problem is, that thread of PlayerMan should wait until proper value of matches is given but I cannot make it work this way. When I type the values it sometimes catches them and decrease amount of matches but that's not exactly what I was up to :) Logics is : I check the value of current player. If it corresponds to this of the thread currently active I use scanner to catch the amount of matches. Else I wait one second (I know it's kinda harsh solution, but I have no other idea how to do it). Class Shared keeps the value of current player, and also amount of matches. By the way, is there any way I can make Player and Shared attributes private instead of public and still make the code work ? CONSOLE and INPUT-DIALOG is just for choosing way of inserting values. class PlayerMan extends Player{ static final int CONSOLE=0; static final int INPUT_DIALOG=1; private int input; public PlayerMan(String name, Shared data, int c){ super(name, data); input = c; } @Override public void run(){ Scanner scanner = new Scanner(System.in); int n = 0; System.out.println("Matches on table: "+data.matchesAmount); System.out.println("which: "+data.which); System.out.println("number: "+number); while(data.matchesAmount != 0){ if(number == data.which){ System.out.println("Choose amount of matches (from 1 to 3): "); n = scanner.nextInt(); if(data.matchesAmount == 1){ System.out.println("There's only 1 match left !"); while(n != 1){ n = scanner.nextInt(); } } else{ do{ n = scanner.nextInt(); } while(n <= 1 && n >= 3); } data.matchesAmount = data.matchesAmount - n; System.out.println(" "+ name+" takes "+n+" matches."); if(number != 0){ data.which = 0; } else{ data.which = 1; } } else{ try { Thread.sleep(1000); } catch(InterruptedException exc) { System.out.println("End of thread."); return; } } System.out.println("Matches on table: "+data.matchesAmount); } if(data.matchesAmount == 0){ System.out.println("Winner is player: "+name); stop(); } } }

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  • Java: define terms initialization, declaration and assignment

    - by HH
    I find the defs circular statements, the subjects are defined by their verbs but the verbs are undefined! So how do you define them? The question is central to understand the term final, related. The Circular Definitions itialization: to initilise a variable. It can be can be done at the time of declaration. assignment: to assign value to a variable. It can be done anywhere. declaration: to declare value to a variable.

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  • [Java] Form data transition into entity beans to persist them by the server side ORM

    - by cscsaba242
    Hello guys, Is there any good explanation or tutorial which describes the common way how can we create entity beans from the received data of the form ? The main reason of my question the treating the received ids (e.g id of country,city and so forth) which is the way from the id to entity ? Example: ................Client side form username:String countryid:Integer (could be a drop down) ................Server side entities public class UserBean { String username; CountryBean Country; } public class CountryBean { String cityname; Integer id; } ............................................ Maybe the question is dependent of the used technology, but I guess there is a very common way. I would like to comprehend the conventional approach of this problem. (For the sake of the completeness I would like to save the form data (received by Stripes) by JPA) Thanks advance. cscsaba242

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  • Java annotations for design patterns?

    - by Greg Mattes
    Is there a project that maintains annotations for patterns? For example, when I write a builder, I want to mark it with @Builder. Annotating in this way immediately provides a clear idea of what the code implements. Also, the Javadoc of the @Builder annotation can reference explanations of the builder pattern. Furthermore, navigating from the Javadoc of a builder implementation to @Builder Javadoc is made easy by annotating @Builder with @Documented. I've being slowing accumulating a small set of such annotations for patterns and idioms that I have in my code, but I'd like to leverage a more complete existing project if it exists. If there is no such project, maybe I can share what I have by spinning it off to a separate pattern/idiom annotation project. Update: I've created the Pattern Notes project in response to this discussion. Contributions welcome! Here is @Builder

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  • Java Backgroundworker: Scope of Widget to be updated unclear

    - by erlord
    Hi all, I am trying to understand the mechanism of org.jdesktop.swingx.BackgroundWorker. Their javadoc presents following example: final JLabel label; class MeaningOfLifeFinder implements BackgroundListener { public void doInBackground(BackgroundEvent evt) { String meaningOfLife = findTheMeaningOfLife(); evt.getWorker().publish(meaningOfLife); } public void process(BackgroundEvent evt) { label.setText("" + evt.getData()); } public void done(BackgroundEvent evt) {} public void started(BackgroundEvent evt) {} } (new MeaningOfLifeFinder()).execute(); Apart from the fact that I doubt the result will ever get published, I wonder how label is passed to the process method, where it is being updated. I thought it's scope is limited to the outside of the BackgroudListener implementation. Quite confused I am ... any answers for me? Thanks in advance

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  • Java static and thread safety or what to do

    - by Parhs
    I am extending a library to do some work for me. Here is the code: public static synchronized String decompile(String source, int flags,UintMap properties,Map<String,String> namesMap) { Decompiler.namesMap=namesMap; String decompiled=decompile(source,flags,properties); Decompiler.namesMap=null; return decompiled; } The problem is that namesMap is static variable. Is that thread safe or not? Because if this code runs concurently namesMap variable may change. What can I do for this?

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  • Java: CSV file read & write.

    - by battousai622
    Im reading in 2 csv file: store_inventory & new_acquisitions... I want to be able to compare the store_inventory csv file with new_acquisitions. 1) If the item names match just update the quantity in store_inventory. 2) If new_acquisitions has a new item that does not exist in store_inventory, then add it to the store_inventory. Heres what i have so far but its not very good. I added comments where i need to add taks 1) & 2). Any advice or code would be great, thanks. File new_acq = new File("/src/test/new_acquisitions.csv"); Scanner acq_scan = null; try { acq_scan = new Scanner(new_acq); } catch (FileNotFoundException ex) { Logger.getLogger(mainpage.class.getName()).log(Level.SEVERE, null, ex); } String itemName; int quantity; Double cost; Double price; File store_inv = new File("/src/test/store_inventory.csv"); Scanner invscan = null; try { invscan = new Scanner(store_inv); } catch (FileNotFoundException ex) { Logger.getLogger(mainpage.class.getName()).log(Level.SEVERE, null, ex); } String itemNameInv; int quantityInv; Double costInv; Double priceInv; while (acq_scan.hasNext()) { String line = acq_scan.nextLine(); if (line.charAt(0) == '#') { continue; } String[] split = line.split(","); itemName = split[0]; quantity = Integer.parseInt(split[1]); cost = Double.parseDouble(split[2]); price = Double.parseDouble(split[3]); while(invscan.hasNext()) { String line2 = invscan.nextLine(); if (line2.charAt(0) == '#') { continue; } String[] split2 = line2.split(","); itemNameInv = split2[0]; quantityInv = Integer.parseInt(split2[1]); costInv = Double.parseDouble(split2[2]); priceInv = Double.parseDouble(split2[3]); if(itemName == itemNameInv) { //update quantity } } //add new entry into csv file } Thanks again for any help. =]

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  • split a string based on pattern in java - capital letters and numbers

    - by rookie
    Hi all I have the following string "3/4Ton". I want to split it as -- word[1] = 3/4 and word[2] = Ton. Right now my piece of code looks like this:- Pattern p = Pattern.compile("[A-Z]{1}[a-z]+"); Matcher m = p.matcher(line); while(m.find()){ System.out.println("The word --> "+m.group()); } It carries out the needed task of splitting the string based on capital letters like:- String = MachineryInput word[1] = Machinery , word[2] = Input The only problem is it does not preserve, numbers or abbreviations or sequences of capital letters which are not meant to be separate words. Could some one help me out with my regular expression coding problem. Thanks in advance...

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  • How to make prevent public key inside jar to be saved using Java code

    - by Abhijith V R
    After signing a jar , we can retrieve the public keys from jar using Certificate[] cert = jarentry.getCertificates(); Once certificate is extracted we can save this to a new keystore as trusted cert. Once this is done , then second user can sign any jar using this certificate , isn't ? I want to distribute content as jars , contents will contain properties files for a application init. I want to make sure that an user is not capable to rebuilding the property files using the certificate he extracted from jarentry. In the code which reads the jar contents i am checking that jar is signed with my certificate only and also checking that jar is not tampered with . But the issue came to my mind that if i am able to extract the cerificate from jar then why don;t a third guy ? Can any one help me in this............

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  • Transposing and Untransposing a String in java

    - by Will
    I have been working on two methods that will Transpose and Untranspose a String respectively. The solutions that I have come up with both work to the best of my knowledge. I just want to know if I could have solved these problems in a simpler way. My code seems like it is too long for the task that is being performed. The first method, transpose(), will take a String as a parameter and transpose it. If "bridge" is entered, the output will be "bergid". Likewise, with the unTranspose() method, if the user enters "bergid", the output will be "bridge". public void transpose( String s ) { String t = ""; int end = s.length() - 1; for ( int i = 0; i < s.length() / 2; i++ ) { t += Character.toString( s.charAt( i ) ) + Character.toString( s.charAt( end ) ); end--; } // Lenth of String is odd if ( s.length() % 2 == 1 ) { // add character in middle of String to the end of the new String t+= Character.toString( s.charAt( s.length() / 2 ) ); } System.out.println( t ); } public void unTranspose( String s ) { String t = ""; // Length of String is odd if ( s.length() % 2 == 1 ) { for ( int i = 0; i < s.length(); i+=2 ) { t+= Character.toString( s.charAt( i ) ); } for ( int i = s.length() - 2; i > 0; i -= 2 ) { t += Character.toString( s.charAt( i ) ); } System.out.println( t ); } // Length of String is even else if ( s.length() % 2 == 0 ) { for ( int i = 0; i < s.length() - 1; i+=2 ) { t+= Character.toString( s.charAt( i ) ); } for ( int i = s.length() - 1; i > 0; i -= 2 ) { t+= Character.toString( s.charAt( i ) ); } System.out.println( t ); } } My code looks horrible. I'm still not used to formatting my code correctly. Please bear with me. Thanks for your time

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  • Passing pointer position to an object in Java.

    - by Gabriel A. Zorrilla
    I've got a JPanel class called Board with a static subclass, MouseHanlder, which tracks the mouse position along the appropriate listener in Board. My Board class has fields pointerX and pointerY. How do i pass the e.getX() and e.getY() from the MouseHandler subclass to its super class JPanel? I tried with getters, setters, super, and cant get the data transfer between subclass and parent class. I'm certain it's a concept issue, but im stuck. Thanks!

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  • How to convert Facebook created_time to Java Date?

    - by smitty
    Hi, I have a FQL statement like this: String query = "SELECT post_id, actor_id, target_id, created_time, message FROM stream WHERE source_id in (SELECT target_id FROM connection WHERE source_id=<userID>) AND is_hidden = 0"; I just wondering what kind of time Facebook gives to me. The result of my statement will be mapped to a wrapper object (wallpost). myDate.setTime(wallpost.getCreated_time()); gives me no valid date. Does anyone have an idea what kind of date Facebook returns and how to match it to Date()? thanks in advance!

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  • Reading XML in Java Applet

    - by Midday
    I know: I have to sign the applet so it can read files How to parse XML files My Questions would be: Should I keep the XML file in the .jar or separate? Are there some best practices tutorials? if so please link me

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  • Java HotSpot 1.6 VM, Garbage Collection - Scary PermGen

    - by Gala101
    Hi, My app shows rising 'Old Generation'/'Tenured Generation' size, and when this reaches the max limit for 'Old Gen', then suddenly PermGen size increases. Here are my generation sizings: -Xmx1200m -Xms1200m -Xmn450m -XX:MaxPermSize=600m -XX:+UseParallelGC This is on 32 bit Fedora so can't have a bigger heap than this. The app is not doing any fancy classloading, though it is using Spring IOC and Hibernate, the Spring App-context.xml defines some 1000 Beans. This app starts with 175MB PermGen, which steadily increases to ~250MB in few hrs, stays that way till Tenured Generation reached ~780 MB, then permgen jumps to ~500MB while Old Gen drops to ~500MB. This forces me to restart the App on daily basis, and gives me real scare of looming OutOfMemory Error.. Any insights would be very helpful. Thanks Gala101

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  • Java - Highest, Lowest and Average

    - by Emily
    Hello, I've just started studying and I need help on one of my exercises. I need the end user to input a rain fall number for each month. I then need to out put the average rainfall, highest month and lowest month and the months which rainfall was above average. I keep getting the same number in the highest and lowest and I have no idea why. I am seriously pulling my hair out. Any help would be greatly appreciated. This is what I have so far: public class rainfall { /** * @param args */ public static void main(String[] args) { int[] numgroup; numgroup = new int [13]; ConsoleReader console = new ConsoleReader(); int highest; int lowest; int index; int tempVal; int minMonth; int minIndex; int maxMonth; int maxIndex; System.out.println("Welcome to Rainfall"); for(index = 1; index < 13; index = index + 1) { System.out.println("Please enter the rainfall for month " + index); tempVal = console.readInt(); while (tempVal>100 || tempVal<0) { System.out.println("The rating must be within 0...100. Try again"); tempVal = console.readInt(); } numgroup[index] = tempVal; } lowest = numgroup[0]; for(minIndex = 0; minIndex < numgroup.length; minIndex = minIndex + 1); { if (numgroup[0] < lowest) { lowest = numgroup[0]; minMonth = minIndex; } } highest = numgroup[1]; for(maxIndex = 0; maxIndex < numgroup.length; maxIndex = maxIndex + 1); { if (numgroup[1] > highest) { highest = numgroup[1]; maxMonth = maxIndex; } } System.out.println("The average monthly rainfall was "); System.out.println("The lowest monthly rainfall was month " + minIndex); System.out.println("The highest monthly rainfall was month " + maxIndex); System.out.println("Thank you for using Rainfall"); } private static ConsoleReader ConsoleReader() { return null; } } Thanks, Emily

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  • Converting a number to a greyscale color in Java

    - by Dave
    Hi, I'm trying to figure out how I can convert a number between 1 and 50 to a greyscale color that could be used here: g.setColor(MyGreyScaleColour); 1 would be lightest (white) and 50 would be darkest (black). e.g. Color intToCol(int colNum) { code here } Any suggestions?

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  • Java: why does extending need an empty constructor?

    - by HH
    I have classes SearchToUser and getFilesToWord. GetFilesToWord must inherit SearchToUser fields. Extending works if an empty construction in SearchToUser-class, otherwise: cannot find symbol symbol : constructor SearchToUser() location: class SearchToUser public class GetFilesToWord extends SearchToUser{ ^ 1 error make: *** [all] Error 1 I cannot understand why the empty constructor is required for extending.

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  • I have a problem wit the following code of java

    - by Sanjeev
    public class b { public static void main(String[] args) { byte b = 1; long l = 127; // b = b + l; // 1 if I try this then its not compile b += l; // 2 if I try this its compile System.out.println(b); } } I don't understand why b=b+1; is not compile and if I write b+=l; then it compile an run.

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