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  • actionlistener not responding in java calculator

    - by tokee
    hi, please see calculator interface code below, from my beginners point of view the "1" should display when it's pressed but evidently i'm doing something wrong. any suggestiosn please? import java.awt.*; import javax.swing.*; import javax.swing.border.*; import java.awt.event.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JPanel; /** *A Class that operates as the framework for a calculator. *No calculations are performed in this section */ public class CalcFrame extends JPanel { private CalcEngine calc; private JFrame frame; private JTextField display; private JLabel status; /** * Constructor for objects of class GridLayoutExample */ //public CalcFrame(CalcEngine engine) //{ //frame.setVisible(true); // calc = engine; // makeFrame(); //} public CalcFrame() { makeFrame(); calc = new CalcEngine(); } class ButtonListener implements ActionListener { ButtonListener() { } public void actionPerformed(ActionEvent e) { if (e.getActionCommand().equals("1")) { System.out.println("1"); } } } /** * This allows you to quit the calculator. */ // Alows the class to quit. private void quit() { System.exit(0); } // Calls the dialog frame with the information about the project. private void showAbout() { JOptionPane.showMessageDialog(frame, "Declan Hodge and Tony O'Keefe Group Project", "About Calculator Group Project", JOptionPane.INFORMATION_MESSAGE); } // ---- swing stuff to build the frame and all its components ---- /** * The following creates a layout of the calculator frame. */ private void makeFrame() { frame = new JFrame("Group Project Calculator"); makeMenuBar(frame); JPanel contentPane = (JPanel)frame.getContentPane(); contentPane.setLayout(new BorderLayout(8, 8)); contentPane.setBorder(new EmptyBorder( 10, 10, 10, 10)); /** * Insert a text field */ display = new JTextField(8); contentPane.add(display, BorderLayout.NORTH); //Container contentPane = frame.getContentPane(); contentPane.setLayout(new GridLayout(4, 5)); JPanel buttonPanel = new JPanel(new GridLayout(4, 4)); contentPane.add(new JButton("9")); contentPane.add(new JButton("8")); contentPane.add(new JButton("7")); contentPane.add(new JButton("6")); contentPane.add(new JButton("5")); contentPane.add(new JButton("4")); contentPane.add(new JButton("3")); contentPane.add(new JButton("2")); contentPane.add(new JButton("1")); contentPane.add(new JButton("0")); contentPane.add(new JButton("+")); contentPane.add(new JButton("-")); contentPane.add(new JButton("/")); contentPane.add(new JButton("*")); contentPane.add(new JButton("=")); contentPane.add(new JButton("C")); contentPane.add(new JButton("CE")); contentPane.add(new JButton("%")); contentPane.add(new JButton("#")); //contentPane.add(buttonPanel, BorderLayout.CENTER); frame.pack(); frame.setVisible(true); } /** * Create the main frame's menu bar. * The frame that the menu bar should be added to. */ private void makeMenuBar(JFrame frame) { final int SHORTCUT_MASK = Toolkit.getDefaultToolkit().getMenuShortcutKeyMask(); JMenuBar menubar = new JMenuBar(); frame.setJMenuBar(menubar); JMenu menu; JMenuItem item; // create the File menu menu = new JMenu("File"); menubar.add(menu); // create the Quit menu with a shortcut "Q" key. item = new JMenuItem("Quit"); item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, SHORTCUT_MASK)); item.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { quit(); } }); menu.add(item); // Adds an about menu. menu = new JMenu("About"); menubar.add(menu); // Displays item = new JMenuItem("Calculator Project"); item.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { showAbout(); } }); menu.add(item); } }

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  • Java method overloading + double dispatch

    - by Max
    Can anybody explain in detail the reason the overloaded method print(Parent parent) is invoked when working with Child instance in my test piece of code? Any pecularities of virtual methods or methods overloading/resolution in Java involved here? Any direct reference to Java Lang Spec? Which term describes this behaviour? Thanks a lot. public class InheritancePlay { public static class Parent { public void doJob(Worker worker) { System.out.println("this is " + this.getClass().getName()); worker.print(this); } } public static class Child extends Parent { } public static class Worker { public void print(Parent parent) { System.out.println("Why this method resolution happens?"); } public void print(Child child) { System.out.println("This is not called"); } } public static void main(String[] args) { Child child = new Child(); Worker worker = new Worker(); child.doJob(worker); } }

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  • 'SImple' 2 class Java calculator doesn't accept inputs or do calculations

    - by Tony O'Keeffe
    Hi, I'm trying to get a two class java calculator working (new to java) to work but so far i'm having no success. the two classes are outlined below, calcFrame is for the interface and calEngine should do the actual calculations but i can't get them to talk to one another. i'd really appreciate any assistance on same. Thanks. CalcFrame Code - import java.awt.; import javax.swing.; import javax.swing.border.; import java.awt.event.; /** *A Class that operates as the framework for a calculator. *No calculations are performed in this section */ public class CalcFrame implements ActionListener { private CalcEngine calc; private JFrame frame; private JTextField display; private JLabel status; /** * Constructor for objects of class GridLayoutExample */ public CalcFrame() { makeFrame(); //calc = engine; } /** * This allows you to quit the calculator. */ // Alows the class to quit. private void quit() { System.exit(0); } // Calls the dialog frame with the information about the project. private void showAbout() { JOptionPane.showMessageDialog(frame, "Group Project", "About Calculator Group Project", JOptionPane.INFORMATION_MESSAGE); } private void makeFrame() { frame = new JFrame("Group Project Calculator"); makeMenuBar(frame); JPanel contentPane = (JPanel)frame.getContentPane(); contentPane.setLayout(new BorderLayout(8, 8)); contentPane.setBorder(new EmptyBorder( 10, 10, 10, 10)); /** * Insert a text field */ display = new JTextField(); contentPane.add(display, BorderLayout.NORTH); //Container contentPane = frame.getContentPane(); contentPane.setLayout(new GridLayout(4, 4)); JPanel buttonPanel = new JPanel(new GridLayout(4, 4)); contentPane.add(new JButton("1")); contentPane.add(new JButton("2")); contentPane.add(new JButton("3")); contentPane.add(new JButton("4")); contentPane.add(new JButton("5")); contentPane.add(new JButton("6")); contentPane.add(new JButton("7")); contentPane.add(new JButton("8")); contentPane.add(new JButton("9")); contentPane.add(new JButton("0")); contentPane.add(new JButton("+")); contentPane.add(new JButton("-")); contentPane.add(new JButton("/")); contentPane.add(new JButton("*")); contentPane.add(new JButton("=")); contentPane.add(new JButton("C")); contentPane.add(buttonPanel, BorderLayout.CENTER); //status = new JLabel(calc.getAuthor()); //contentPane.add(status, BorderLayout.SOUTH); frame.pack(); frame.setVisible(true); } /** * Create the main frame's menu bar. * The frame that the menu bar should be added to. */ private void makeMenuBar(JFrame frame) { final int SHORTCUT_MASK = Toolkit.getDefaultToolkit().getMenuShortcutKeyMask(); JMenuBar menubar = new JMenuBar(); frame.setJMenuBar(menubar); JMenu menu; JMenuItem item; // create the File menu menu = new JMenu("File"); menubar.add(menu); // create the Quit menu with a shortcut "Q" key. item = new JMenuItem("Quit"); item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, SHORTCUT_MASK)); item.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { quit(); } }); menu.add(item); // Adds an about menu. menu = new JMenu("About"); menubar.add(menu); // Displays item = new JMenuItem("Calculator Project"); item.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { showAbout(); } }); menu.add(item); } /** * An interface action has been performed. * Find out what it was and handle it. * @param event The event that has occured. */ public void actionPerformed(ActionEvent event) { String command = event.getActionCommand(); if(command.equals("0") || command.equals("1") || command.equals("2") || command.equals("3") || command.equals("4") || command.equals("5") || command.equals("6") || command.equals("7") || command.equals("8") || command.equals("9")) { int number = Integer.parseInt(command); calc.numberPressed(number); } else if(command.equals("+")) { calc.plus(); } else if(command.equals("-")) { calc.minus(); } else if(command.equals("=")) { calc.equals(); } else if(command.equals("C")) { calc.clear(); } else if(command.equals("?")) { } // else unknown command. redisplay(); } /** * Update the interface display to show the current value of the * calculator. */ private void redisplay() { display.setText("" + calc.getDisplayValue()); } /** * Toggle the info display in the calculator's status area between the * author and version information. */ } CalcEngine - public class CalcEngine { // The calculator's state is maintained in three fields: // buildingDisplayValue, haveLeftOperand, and lastOperator. // The current value (to be) shown in the display. private int displayValue; // The value of an existing left operand. private int leftOperand; /** * Create a CalcEngine. */ public CalcEngine() { clear(); } public int getDisplayValue() { return displayValue; } /** * A number button was pressed. * Either start a new operand, or incorporate this number as * the least significant digit of an existing one. * @param number The number pressed on the calculator. */ public void numberPressed(int number) { if(buildingDisplayValue) { // Incorporate this digit. displayValue = displayValue*10 + number; } else { // Start building a new number. displayValue = number; buildingDisplayValue = true; } } /** * The 'plus' button was pressed. */ public void plus() { applyOperator('+'); } /** * The 'minus' button was pressed. */ public void minus() { applyOperator('-'); } /** * The '=' button was pressed. */ public void equals() { // This should completes the building of a second operand, // so ensure that we really have a left operand, an operator // and a right operand. if(haveLeftOperand && lastOperator != '?' && buildingDisplayValue) { calculateResult(); lastOperator = '?'; buildingDisplayValue = false; } else { keySequenceError(); } } /** * The 'C' (clear) button was pressed. * Reset everything to a starting state. */ public void clear() { lastOperator = '?'; haveLeftOperand = false; buildingDisplayValue = false; displayValue = 0; } /** * @return The title of this calculation engine. */ public String getTitle() { return "Java Calculator"; } /** * @return The author of this engine. */ public String getAuthor() { return "David J. Barnes and Michael Kolling"; } /** * @return The version number of this engine. */ public String getVersion() { return "Version 1.0"; } /** * Combine leftOperand, lastOperator, and the * current display value. * The result becomes both the leftOperand and * the new display value. */ private void calculateResult() { switch(lastOperator) { case '+': displayValue = leftOperand + displayValue; haveLeftOperand = true; leftOperand = displayValue; break; case '-': displayValue = leftOperand - displayValue; haveLeftOperand = true; leftOperand = displayValue; break; default: keySequenceError(); break; } } /** * Apply an operator. * @param operator The operator to apply. */ private void applyOperator(char operator) { // If we are not in the process of building a new operand // then it is an error, unless we have just calculated a // result using '='. if(!buildingDisplayValue && !(haveLeftOperand && lastOperator == '?')) { keySequenceError(); return; } if(lastOperator != '?') { // First apply the previous operator. calculateResult(); } else { // The displayValue now becomes the left operand of this // new operator. haveLeftOperand = true; leftOperand = displayValue; } lastOperator = operator; buildingDisplayValue = false; } /** * Report an error in the sequence of keys that was pressed. */ private void keySequenceError() { System.out.println("A key sequence error has occurred."); // Reset everything. clear(); } }

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  • How to protect compiled Java classes?

    - by Registered User
    I know, many similar questions has been asked here. I am not asking if I can protect my compiled Java class - because obviously you will say 'no you can't'. I am asking what is the best known method of protecting Java classes against de-compiling? If you aware of any research or academic paper in this field please do let me know. Also if you have used some methods or software please share you experience? Any kind of information will be very useful. Thank you.

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  • Why GWT? Advantages and Trade-Offs of Using This RIA Framework

    - by prometheus
    I'm new to stackoverflow and have been reading through a bunch of the "highest voted" questions for GWT. Several of these questions talk about the pitfalls or problems with GWT. In the articles: Which Javascript framework (jQuery vs Dojo vs … )? and Biggest GWT Pitfalls?, some posters seem to suggest that GWT is not lightweight enough or that there are better alternatives that may be used. Do most of you feel that there are problems with GWT that have not been fixed with GWT 2.0 -- which would make you inclined to suggest using a simpler framework for a new project? To some extent, shouldn't GWT be somewhat future-proof (since you don't have to worry about it changing drastically from release to release and since it is backed by Google)? I realize that the answer to this question depends greatly upon what you want to do or what you wish to make. I am looking at this from the perspective of starting a new web application that will eventually be used by millions of users.

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  • Java - Highest, Lowest and Average

    - by Emily
    Right, so why does Java come up with this error: Exception in thread "main" java.lang.Error: Unresolved compilation problem: Type mismatch: cannot convert from double to int at rainfall.main(rainfall.java:38) From this: public class rainfall { /** * @param args */ public static void main(String[] args) { int[] numgroup; numgroup = new int [12]; 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"); // Input (index now 0-based) for(index = 0; index < 12; index = index + 1) { System.out.println("Please enter the rainfall for month " + index + 1); tempVal = console.readInt(); while (tempVal100 || tempVal<0) { System.out.println("The rating must be within 0...100. Try again"); tempVal = console.readInt(); } numgroup[index] = tempVal; } lowest = numgroup[0]; highest = numgroup[0]; int total = 0.0; // Loop over data (using 1 loop) for(index = 0; index < 12; index = index + 1) { int curr = numgroup[index]; if (curr < lowest) { lowest = curr; minIndex = index; } if (curr highest) { highest = curr; maxIndex = index; } total += curr; } float avg = (float)total / numgroup.length; System.out.println("The average monthly rainfall was " + avg); // +1 to go from 0-based index to 1-based month System.out.println("The lowest monthly rainfall was month " + minIndex + 1); System.out.println("The highest monthly rainfall was month " + maxIndex + 1); System.out.println("Thank you for using Rainfall"); } private static ConsoleReader ConsoleReader() { return null; } }

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  • Java 'Prototype' pattern - new vs clone vs class.newInstance

    - by Guillaume
    In my project there are some 'Prototype' factories that create instances by cloning a final private instance. The author of those factories says that this pattern provides better performance than calling 'new' operator. Using google to get some clues about that, I've found nothing really relevant about that. Here is a small excerpt found in a javdoc from an unknown project javdoc from an unknown project Sadly, clone() is rather slower than calling new. However it is a lot faster than calling java.lang.Class.newInstance(), and somewhat faster than rolling our own "cloner" method. For me it's looking like an old best practice of the java 1.1 time. Does someone know more about this ? Is this a good practice to use that with 'modern' jvm ?

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  • Auto Encryption of web.config connection string

    - by Klaas Jan
    I want to encrypt the connection string in web.config, the problem is each time a developer changes the connection string in web.config and publishes, it needs to be encrypted every time in the web server. Is there any way that the connection string can encrypted automatically every time someone publishes it? Note :- All of us work on our local machines other than the server. So encryption using local machine key is not an option.

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  • Are there macro facility for Java or C#?

    - by h2g2java
    Macros are useful. Therefore, I occasionally bemoan the absence of macros in Java and C#. Macros allow me to force in-line but allow me the code-manageability of non-macro code. Is there any Java- or C#-based project/product somewhere out there that effectively allow macros or specifying in-line expansion. I am thinking of something like @macro public void hello(int x){ ... } or when I call a method, an @inline annotation preceding the call would effect the called-method to be in-lined. or, should I need to know that I should just trust the compiler to make the best the decision for me that at the best of its analysis it might in-line a call. I hope this question will not lead to debating the pro/cons/usefulness of macros.

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  • Jax-ws 2.2 or Metro as Tomcat runtime environment

    - by EugeneP
    I need an implementation of JAX-WS, that is RUNTIME ENVIRONMENT to use a client for Tomcat6. Which is better in your opinion? JAX-WS 2.2 https://jax-ws.dev.java.net/2.2/ Metro 2.0 https://metro.dev.java.net/2.0/ They have different installation procedures and different jars. For now I only need to be able to run a client from under Tomcat6 web apps. But later I'm planning to use ApacheCXF soap web-service, that will run on this Tomcat. As I understand, CXF is a unique implementation that does not any of mentioned runtime environments, so I guess whatever between metro & jax-ws2.2 I choose does not matter, right? Still, which one do you recommend?

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  • [java] Efficiency of while(true) ServerSocket Listen

    - by Submerged
    I am wondering if a typical while(true) ServerSocket listen loop takes an entire core to wait and accept a client connection (Even when implementing runnable and using Thread .start()) I am implementing a type of distributed computing cluster and each computer needs every core it has for computation. A Master node needs to communicate with these computers (invoking static methods that modify the algorithm's functioning). The reason I need to use sockets is due to the cross platform / cross language capabilities. In some cases, PHP will be invoking these java static methods. I used a java profiler (YourKit) and I can see my running ServerSocket listen thread and it never sleeps and it's always running. Is there a better approach to do what I want? Or, will the performance hit be negligible? Please, feel free to offer any suggestion if you can think of a better way (I've tried RMI, but it isn't supported cross-language. Thanks everyone

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  • Java, searching through folders to match a name

    - by Nick
    Hi folks, I using java to search for a file or folder that matches a specific case. For instance i want to search through all the files and folders and iterate through them as many times as necessary untill i find a result. The catch I searching for files and folders through a binary image of a file system. This means i doubt there are any preexisting classes such java.file.* to do it for me. If it helps i can tell you that i can tell the difference between files and folders easily enough. (a folder is flagged as 0x20) The only way i can think of is to do a standard loop and iterated several times but this limits me if a file or folder is several folders deep. All input greatly welcome

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  • groovy (java) error grabbing files

    - by senzacionale
    i can not grab files. I get: java.lang.RuntimeException: Error grabbing Grapes -- [unresolved dependency: org.apache.ivy#ivy;2.1.0: not found start of script which grab files import groovy.text.SimpleTemplateEngine import java.security.MessageDigest import org.apache.commons.cli.OptionBuilder import org.apache.commons.cli.Options import org.apache.commons.cli.PosixParser import org.apache.commons.io.FileUtils import org.apache.ivy.core.settings.IvySettings import org.apache.ivy.plugins.parser.m2.PomModuleDescriptorParser import org.apache.tools.ant.Project import org.apache.tools.ant.ProjectHelper import org.apache.tools.ant.types.Path import org.apache.commons.cli.HelpFormatter //First grab the grapes we need for the script and create a few beans to hold some values @Grab(group = 'org.apache.ant', module = 'ant', version = '1.7.1') @Grab(group = 'commons-io', module = 'commons-io', version = '1.4') @Grab(group = 'commons-cli', module = 'commons-cli', version = '1.2') @Grab(group = 'org.apache.ivy', module = 'ivy', version = '2.1.0')

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  • AES decryption in Java - IvParameterSpec to big

    - by user1277269
    Im going to decrypt a plaintext with two keys. As you see in the picture were have one encrypted file wich contains KEY1(128 bytes),KEYIV(128 bytes),key2(128bytes) wich is not used in this case then we have the ciphertext. The error I get here is "Exception in thread "main" java.security.InvalidAlgorithmParameterException: Wrong IV length: must be 16 bytes long. but it is 64 bytes." Picture: http://i264.photobucket.com/albums/ii200/XeniuM05/bg_zps0a523659.png public class AES { public static void main(String[] args) throws Exception { byte[] encKey1 = new byte[128]; byte[] EncIV = new byte[256]; byte[] UnEncIV = new byte[128]; byte[] unCrypKey = new byte[128]; byte[] unCrypText = new byte[1424]; File f = new File("C://ftp//ciphertext.enc"); FileInputStream fis = new FileInputStream(F); byte[] EncText = new byte[(int) f.length()]; fis.read(encKey1); fis.read(EncIV); fis.read(EncText); EncIV = Arrays.copyOfRange(EncIV, 128, 256); EncText = Arrays.copyOfRange(EncText, 384, EncText.length); System.out.println(EncText.length); KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType()); char[] password = "lab1StorePass".toCharArray(); java.io.FileInputStream fos = new java.io.FileInputStream( "C://ftp//lab1Store"); ks.load(fos, password); char[] passwordkey1 = "lab1KeyPass".toCharArray(); PrivateKey Lab1EncKey = (PrivateKey) ks.getKey("lab1EncKeys", passwordkey1); Cipher rsaDec = Cipher.getInstance("RSA"); // set cipher to RSA decryption rsaDec.init(Cipher.DECRYPT_MODE, Lab1EncKey); // initalize cipher ti lab1key unCrypKey = rsaDec.doFinal(encKey1); // Decryps first key UnEncIV = rsaDec.doFinal(EncIV); //decryps encive byte array to undecrypted bytearray---- OBS! Error this is 64 BYTES big, we want 16? System.out.println("lab1key "+ unCrypKey +" IV " + UnEncIV); //-------CIPHERTEXT decryption--------- Cipher AESDec = Cipher.getInstance("AES/CBC/PKCS5Padding"); //---------convert decrypted bytearrays to acctual keys SecretKeySpec unCrypKey1 = new SecretKeySpec(unCrypKey, "AES"); IvParameterSpec ivSpec = new IvParameterSpec(UnEncIV); AESDec.init(Cipher.DECRYPT_MODE, unCrypKey1, ivSpec ); unCrypText = AESDec.doFinal(EncText); // Convert decrypted cipher bytearray to string String deCryptedString = new String(unCrypKey); System.out.println(deCryptedString); }

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  • Java resource as file

    - by Martin Riedel
    Is there a way in Java to construct a File instance on a resource retrieved from a jar through the classloader? My application uses some files from the jar (default) or from a filesystem directory specified at runtime (user input). I'm looking for a consistent way of a) loading these files as a stream b) listing the files in the user-defined directory or the directory in the jar respectively Edit: Apparently, the ideal approach would be to stay away from java.io.File altogether. Is there a way to load a directory from the classpath and list its contents (files/entities contained in it)?

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  • java.util.regex.* Recursive matching

    - by amit.bhayani
    Hi Guys, I have been using the java.util.regex.* classes for Regular Expression in Java and all good so far. But today I have a different requirement. For example consider the pattern to be "aabb". Now if the input String is aa it will definitely not match, however there is still possibility that if I append bb it becomes aabb and it matches. However if I would have started with cc, no matter what I append it will never match. I have explored the Pattern and Matcher class but didn't find any way of achieving this. The input will come from user and system have to wait till pattern matches or it will never match irrespective of any input further. Any clue? Thanks.

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  • Problem with greek characters using java

    - by Subhendu Mahanta
    I am trying to write greek characters to a file using java like this: String greek = "\u03c1\u03ae\u03bc. \u03c7\u03b1\u03b9\u03c1\u03b5\u03c4\u03ce"; try { BufferedWriter out = new BufferedWriter(new FileWriter("E:\\properties\\outfilename.txt")); out.write(greek); out.close(); } catch (IOException e) { } Not working. Tried to use javac -encoding ISO-8859-7. Also tried java -Dfile.encoding=ISO-8859-7. Assuming that as I do not have greek font in my pc, I downloaded achillies (greek font - Ach4.ttf).Installed it by going to control panel fonts. Any ideas?

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