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  • Web Form based login in Java

    - by BrunoLM
    How can I block access to the site if a user is not logged in? Under web.xml Security I checked Form authentication then I selected Login and Error page, but I don't know how to block the access and redirect the user to the login page. Do I need a filter? If so, how can I get the login url I specified? And how should I call the validation method? I saw in some examples this code <form method=post action="j_security_check"> <input type="text" name="j_username" /> <input type="password" name="j_password" /> </form> What does it do?

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  • Java String replaceAll with conditions

    - by user1483570
    I am not good in regular expressions and I need help in replacing the string. String str = "Name_XYZ_"; str = "XYZ_NAME_"; So how can I replace "Name_" or "_NAME_" from above two strings with empty string? The conditions are "Name" can be in any case and it can be at index 0 or at any index but preceded by "_". So far I tried, String replacedString = str.replaceAll("(?i)Name_", ""); // This is not correct. This is not the homework. I am working on XML file that needs such kind of processing. Please help. Thank you.

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  • Java's Swing Threading

    - by nevets1219
    My understanding is that if I start up another thread to perform some actions, I would need to SwingUtilities.invokeAndWait or SwingUtilities.invokeLater to update the GUI while I'm in said thread. Please correct me if I'm wrong. What I'm trying to accomplish is relatively straightforward: when the user clicks submit, I want to (before performing any actions) disable the submit button, perform the action, and at the end of the action re-enable the button. My method to perform the action updates the GUI directly (displays results) when it gets the results back. This action basically queries a server and gets some results back. What I have so far is: boolean isRunning = false; synchronized handleButtonClick() { if ( isRunning == false ) { button.setEnabled( false ); isRunning = true; doAction(); } } doAction() { new Thread() { try { doAction(); // Concern A } catch ( ... ) { displayStackTrace( ... ); // Concern B } finally { SwingUtilities.invokeLater ( /* simple Runnable to enable button */ ); isRunning = false; } } } For both of my concerns above, do I would have to use SwingUtilities.invokeAndWait since they both will update the GUI? All GUI updates revolve around updating JTextPane. Do I need to in my thread check if I'm on EDT and if so I can call my code (regardless of whether it updates the GUI or not) and NOT use SwingUtilities.invokeAndWait?

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  • Freeing Java memory at a specific point in time

    - by Marcus
    Given this code, where we load a lot of data, write it to a file, and then run an exe.. void myMethod() { Map stuff = createMap(); //Consumes 250 MB memory File file = createFileInput(stuff); //Create input for exe runExectuable(file); //Run Windows exe } What is the best way to release the memory consumed by stuff prior to running the exe? We don't need this in memory any more as we have dumped the data to a file for input to the exe... Is the best method to just set stuff = null prior to runExecutable(file)?

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  • Simple Question:Output of below Java program

    - by Abhishek Jain
    public class abc1 { private String s; public abc1(String s){this.s=s;} public static void main(String args[]) { HashSet<Object> hs=new HashSet<Object>(); abc1 a1= new abc1("abc"); abc1 a2= new abc1("abc"); String s1= new String("abc"); String s2= new String("abc"); hs.add(a1); hs.add(a2); hs.add(s1); hs.add(s2); System.out.println(hs.size()); } } Why above program output is 3?

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  • How are ambigous methods resolved in java ?

    - by Jijoy
    Hi, I have a question. package org.study.algos; public class Study { public static void main(String[] args) { A a = new A(); a.m1(null); } } class A { public void m1(String s) { System.out.println("String"); System.out.println(s); } public void m1(Object obj) { System.out.println("Object"); System.out.println(obj); } } Here, the output is String null Why does the JVM resolve the method to one with a String argument? Thanks in advance J

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  • Java Sound Clip Looping Frame Position

    - by InsertNickHere
    Hi, I have a little problem with a loopting clip: If you have a soundfile e.g. 20000 samples long, the frame position will not reset after looping, so I get values that are "out of bounds" of the original soundfile. As I want to draw a position marker on my waveform, I'm a bit confused how to achive. At this time I just get myClip.getLongFramePosition() but this does not work as described above. Does anyone have an idea how to fix that? Is there a possibility to count how often a clip was looped before? Regards

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  • Java Split not working as expected

    - by daaabears
    I am trying to use a simple split to break up the following string: 00-00000 My expression is: ^([0-9][0-9])(-)([0-9])([0-9])([0-9])([0-9])([0-9]) And my usage is: String s = "00-00000"; String pattern = "^([0-9][0-9])(-)([0-9])([0-9])([0-9])([0-9])([0-9])"; String[] parts = s.split(pattern); If I play around with the Pattern and Matcher classes I can see that my pattern does match and the matcher tells me my groupCount is 7 which is correct. But when I try and split them I have no luck.

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  • Adapting pseudocode to java implementation for finding the longest word in a trie

    - by user1766888
    Referring to this question I asked: How to find the longest word in a trie? I'm having trouble implementing the pseudocode given in the answer. findLongest(trie): //first do a BFS and find the "last node" queue <- [] queue.add(trie.root) last <- nil map <- empty map while (not queue.empty()): curr <- queue.pop() for each son of curr: queue.add(son) map.put(son,curr) //marking curr as the parent of son last <- curr //in here, last indicate the leaf of the longest word //Now, go up the trie and find the actual path/string curr <- last str = "" while (curr != nil): str = curr + str //we go from end to start curr = map.get(curr) return str This is what I have for my method public static String longestWord (DTN d) { Queue<DTN> holding = new ArrayQueue<DTN>(); holding.add(d); DTN last = null; Map<DTN,DTN> test = new ArrayMap<DTN,DTN>(); DTN curr; while (!holding.isEmpty()) { curr = holding.remove(); for (Map.Entry<String, DTN> e : curr.children.entries()) { holding.add(curr.children.get(e)); test.put(curr.children.get(e), curr); } last = curr; } curr = last; String str = ""; while (curr != null) { str = curr + str; curr = test.get(curr); } return str; } I'm getting a NullPointerException at: for (Map.Entry<String, DTN> e : curr.children.entries()) How can I find and fix the cause of the NullPointerException of the method so that it returns the longest word in a trie?

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  • Java regex to get part number

    - by Blankman
    I have HTML that I need to extract a part number from, the HTML looks like: javascript:selectItem('ABC123 1', '..... I need to get the ABC123 from the above. My code snippet: Patterp p = Pattern.Compile("?????"); Matcher m = p.matcher(html); if(m.find()) partNumber = m.group(1).trim(); BTW, in the pattern, how do I escape for the character ( I now for quotes I do \" thanks allot!

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  • Java Detect Variable Change Using PropertyChangeSupport and PropertyChangeListener

    - by Sam
    I'm trying to print out debug statements when some third party code changes a variable. For example, consider the following: public final class MysteryClass { private int secretCounter; public synchronized int getCounter() { return secretCounter; } public synchronized void incrementCounter() { secretCounter++; } } public class MyClass { public static void main(String[] args) { MysteryClass mysteryClass = new MysteryClass(); // add code here to detect calls to incrementCounter and print a debug message } I don't have the ability to change the 3rd party MysteryClass, so I thought that I could use PropertyChangeSupport and PropertyChangeListener to detect changes to the secretCounter: public class MyClass implements PropertyChangeListener { private PropertyChangeSupport propertySupport = new PropertyChangeSupport(this); public MyClass() { propertySupport.addPropertyChangeListener(this); } public void propertyChange(PropertyChangeEvent evt) { System.out.println("property changing: " + evt.getPropertyName()); } public static void main(String[] args) { MysteryClass mysteryClass = new MysteryClass(); // do logic which involves increment and getting the value of MysteryClass } } Unfortunately, this did not work and I have no debug messages printed out. Does anyone see what is wrong with my implementation of the PropertyChangeSupport and Listener interfaces? I want to print a debug statement whenever incrementCounter is called or the value of secretCounter changes.

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  • Java regex skipping matches

    - by Mihail Burduja
    I have some text; I want to extract pairs of words that are not separated by punctuation. Thi is the code: //n-grams Pattern p = Pattern.compile("[a-z]+"); if (n == 2) { p = Pattern.compile("[a-z]+ [a-z]+"); } if (n == 3) { p = Pattern.compile("[a-z]+ [a-z]+ [a-z]+"); } Matcher m = p.matcher(text.toLowerCase()); ArrayList<String> result = new ArrayList<String>(); while (m.find()) { String temporary = m.group(); System.out.println(temporary); result.add(temporary); } The problem is that it skips some matches. For example "My name is James", for n = 3, must match "my name is" and "name is james", but instead it matches just the first. Is there a way to solve this?

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  • Java: refactoring static constants

    - by akf
    We are in the process of refactoring some code. There is a feature that we have developed in one project that we would like to now use in other projects. We are extracting the foundation of this feature and making it a full-fledged project which can then be imported by its current project and others. This effort has been relatively straight-forward but we have one headache. When the framework in question was originally developed, we chose to keep a variety of constant values defined as static fields in a single class. Over time this list of static members grew. The class is used in very many places in our code. In our current refactoring, we will be elevating some of the members of this class to our new framework, but leaving others in place. Our headache is in extracting the foundation members of this class to be used in our new project, and more specifically, how we should address those extracted members in our existing code. We know that we can have our existing Constants class subclass this new project's Constants class and it would inherit all of the parent's static members. This would allow us to effect the change without touching the code that uses these members to change the class name on the static reference. However, the tight coupling inherent in this choice doesn't feel right. before: public class ConstantsA { public static final String CONSTANT1 = "constant.1"; public static final String CONSTANT2 = "constant.2"; public static final String CONSTANT3 = "constant.3"; } after: public class ConstantsA extends ConstantsB { public static final String CONSTANT1 = "constant.1"; } public class ConstantsB { public static final String CONSTANT2 = "constant.2"; public static final String CONSTANT3 = "constant.3"; } In our existing code branch, all of the above would be accessible in this manner: ConstantsA.CONSTANT2 I would like to solicit arguments about whether this is 'acceptable' and/or what the best practices are.

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  • Calling class in Java after editing file used in as source for table

    - by user2892290
    I'm currently working on a project, I'll try to subrscibe first. I save data into text file, that I use as a source for browser of that data. The browser is based on table that contains the data. I have to rewrite the source file everytime I delete or edit data. That's where the problem comes in. After deleting or editing data I call a method to create the table again, but the table never creates. Is it possibly made by editing the file and calling the method right after that? If I restart my app the table is successfully created with right data. Take in note that I don't get any error message. This is the method I use for loading data from source file: try (BufferedReader input1 = new BufferedReader(new FileReader("./src/data.src"))) { int lines = 0; while (input1.read() != -1) { if (!(input1.readLine()).equals("")) { lines++; } } input1.close(); if (lines == 0) { JOptionPane.showMessageDialog(null, "No data to load, create a note first!"); new Writer().build(frame); } else { try (BufferedReader input = new BufferedReader(new FileReader("./src/data.src"))) { Game[] g = new Game[lines]; String currentLine; String[] help; int counter = 0; while (lines > 0) { currentLine = input.readLine(); help = currentLine.split("#"); g[counter] = new Game(help[0],help[1], help[2], help[3], help[4], help[5], help[6], help[7], help[8], help[9]); counter++; lines--; } input.close(); final JButton bButton = new backButton().create(frame, mPanel); build(g, frame, bButton); mPanel.add(panel); mPanel.add(panel2); mPanel.add(searchPanel); mPanel.add(bButton); bButton.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { frame.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR)); panel.removeAll(); frame.setCursor(Cursor.getDefaultCursor()); } }); mPanel.setPreferredSize(new Dimension(1000, 750)); panel.setBorder(new EmptyBorder(10, 10, 10, 10)); frame.setLayout(new FlowLayout()); frame.add(mPanel); frame.pack(); JMenuBar menuBar = new Menu().create(frame, mPanel); frame.setJMenuBar(menuBar); frame.setVisible(true); Rectangle rec = GraphicsEnvironment.getLocalGraphicsEnvironment().getMaximumWindowBounds(); int width = (int) rec.getWidth(); int height = (int) rec.getHeight(); frame.setBounds(1, 3, width, height); frame.addComponentListener(new ComponentAdapter() { @Override public void componentMoved(ComponentEvent e) { frame.setLocation(1, 3); } }); And this is the method I use for creating the table: String[][] tableData = new String[g.length][9]; for (int i = 0; i < tableData.length; i++) { tableData[i][0] = g[i].getChampion(); tableData[i][1] = g[i].getRole(); tableData[i][2] = g[i].getEnemy(); tableData[i][3] = g[i].getDifficulty(); tableData[i][4] = g[i].getResult(); tableData[i][5] = g[i].getScore(); tableData[i][6] = g[i].getGameType(); tableData[i][7] = g[i].getPoints(); tableData[i][8] = g[i].getLeague(); } final JLabel searchLabel = new JLabel("Search for champion played."); final JButton searchButton = new JButton("Search"); final JTextField searchText = new JTextField(20); frame.setTitle("LoL Notepad - reading your notes"); JTable table = new JTable(tableData, columnNames); final JScrollPane scrollPane = new JScrollPane(table); scrollPane.setPreferredSize(new Dimension(980, 500)); panel2.setPreferredSize(new Dimension(1000, 550)); panel2.setVisible(false); panel2.setBorder(new EmptyBorder(10, 10, 10, 10)); panel3.setVisible(false); panel.setLayout(new FlowLayout()); panel.add(scrollPane); searchPanel.add(searchLabel); searchPanel.add(searchText); searchPanel.add(searchButton); searchButton.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { try { frame.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR)); search(g, searchText.getText(), frame, bButton); frame.setCursor(Cursor.getDefaultCursor()); } catch (IOException ex) { Logger.getLogger(Reader.class.getName()).log(Level.SEVERE, null, ex); } } }); table.addMouseListener(new MouseAdapter() { @Override public void mousePressed(MouseEvent e) { if (e.getClickCount() == 1) { JTable target = (JTable) e.getSource(); panel.setVisible(false); searchPanel.setVisible(false); bButton.setVisible(false); int row = target.getSelectedRow(); specific(row, g, frame, bButton); } } });

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  • Java Swing: JTextArea columns question

    - by battousai622
    How do i put the text in specific columns with jTextArea? private javax.swing.JTextArea jTextArea1; jTextArea1.setColumns(4); jTextArea1.insert(price, 0); //column 1 jTextArea1.insert(cost, 0); //column 2 jTextArea1.insert(quantity, 0); //column ect.. jTextArea1.insert(itemName, 0); jTextArea1.insert("\n", 0);

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  • Java: Reflection against casting when you know superclass

    - by Ema
    I don't know exactly how to define my doubt so please be patient if the question has already been asked. Let's say I have to dinamically instantiate an object. This object will surely be instance of a subclass of a known, immutable class A. I can obtain dinamically the specific implementation class. Would it be better to use reflection exactly as if I didn't know anything about the target class, or would it be preferrable/possible to do something like: A obj = (Class.forName("com.package.Sub-A")) new A(); where Sub-A extends A ? The purpose would be to avoid reflection overhead times... Thank you in advance.

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  • Java Download Concurrent Data

    - by xger86x
    Hi, i'm developing an app which download map tiles around different places in a city. To do this, i have one thread for each place in which i select the tiles and create a thread to download each. Well, the question is how to avoid creating a thread for a tile that already exists in the thread pool. Should not just check if the file exists, since it is possible that the thread for that tile already exists (other place already need that tile) but the file has not been created- Any idea? Thanks

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  • java /TableModel of Objects/Update Object"

    - by Tomás Ó Briain
    I've a collection of Stock objects that I'm updating about 10/15 variables for in real-time. I'm accessing each Stock by its ID in the collection. I'm also trying to display this in a JTable and have implemented an AbstractTablemodel. It's not working too well. I've a RowMap that I add each ID to as Stocks are added to the TableModel. To update the prices and variables of all the stocks in the TableModel, I want to send a Stock object to an updateModel(Stock s) method. I can find the relevant row by searching the map, but how do I handle this nicely, so I don't have to start iterating through table columns and comparing the values of the cells to the variables of the object to see whether there are any differences?? Basically, i want to send a Stock object to the TableModel and update cells if there are changes and do nothing if there aren't. Any ideas about how to implement a TableModel that might do this? Any pointeres at all would be appreciated. Thanks.

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  • Java-Recursion: When does statements after a recursive method call executes

    - by Ruru Morlano
    When are statements after the method call itself going to execute? private void inorderHelper(TreeNode node) { if ( node==null ) return; inorderHelper(node.leftNode); System.out.printf("%d", node.data); inorderHelper(node.rigthNode); } All I can see is that the line of codes inorderHelper(node.leftNode) will continue to iterate until node == null and the method terminates immediately before node.data is printed. I think that I didn't get well recursion but all examples I can find doesn't have statements after the recursive call. All I want to know is when are statements like System.out.printf("%d",node.data) going to execute before the method return?

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  • Creating a New Reverse Java Array

    - by mandir08
    Given an array of ints length 3, return a new array with the elements in reverse order, so {1, 2, 3} becomes {3, 2, 1}. public int[] reverse3(int[] nums) { int[] values = new int[3]; for(int i=0; i<=nums.length-1; i++) { for(int j=nums.length-1; j>=0; j--) { values[i]=nums[j]; } } return values; } I cant get this to work properly, usually the last int in the array, becomes every single int in the new array

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