ProgressBar Demo 2 : ProgressBar « Swing JFC « Java






ProgressBar Demo 2

ProgressBar Demo 2
  
/* From http://java.sun.com/docs/books/tutorial/index.html */

/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
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 *  list of conditions and the following disclaimer.
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 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
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 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
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import java.awt.BorderLayout;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

/*
 * ProgressBarDemo2.java is a 1.4 application that requires these files:
 * LongTask.java SwingWorker.java
 */
public class ProgressBarDemo2 extends JPanel implements ActionListener {
  public final static int ONE_SECOND = 1000;

  private JProgressBar progressBar;

  private Timer timer;

  private JButton startButton;

  private LongTask task;

  private JTextArea taskOutput;

  private String newline = "\n";

  public ProgressBarDemo2() {
    super(new BorderLayout());
    task = new LongTask();

    //Create the demo's UI.
    startButton = new JButton("Start");
    startButton.setActionCommand("start");
    startButton.addActionListener(this);

    progressBar = new JProgressBar(0, task.getLengthOfTask());
    progressBar.setValue(0);

    //We call setStringPainted, even though we don't want the
    //string to show up until we switch to determinate mode,
    //so that the progress bar height stays the same whether
    //or not the string is shown.
    progressBar.setStringPainted(true); //get space for the string
    progressBar.setString(""); //but don't paint it

    taskOutput = new JTextArea(5, 20);
    taskOutput.setMargin(new Insets(5, 5, 5, 5));
    taskOutput.setEditable(false);

    JPanel panel = new JPanel();
    panel.add(startButton);
    panel.add(progressBar);

    add(panel, BorderLayout.PAGE_START);
    add(new JScrollPane(taskOutput), BorderLayout.CENTER);
    setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));

    //Create a timer.
    timer = new Timer(ONE_SECOND, new ActionListener() {
      public void actionPerformed(ActionEvent evt) {
        progressBar.setValue(task.getCurrent());
        String s = task.getMessage();
        if (s != null) {
          if (progressBar.isIndeterminate()) {
            progressBar.setIndeterminate(false);
            progressBar.setString(null); //display % string
          }
          taskOutput.append(s + newline);
          taskOutput.setCaretPosition(taskOutput.getDocument()
              .getLength());
        }
        if (task.isDone()) {
          Toolkit.getDefaultToolkit().beep();
          timer.stop();
          startButton.setEnabled(true);
          progressBar.setValue(progressBar.getMinimum());
          progressBar.setString(""); //hide % string
        }
      }
    });
  }

  /**
   * Called when the user presses the start button.
   */
  public void actionPerformed(ActionEvent evt) {
    progressBar.setIndeterminate(true);
    startButton.setEnabled(false);
    task.go();
    timer.start();
  }

  /**
   * Create the GUI and show it. For thread safety, this method should be
   * invoked from the event-dispatching thread.
   */
  private static void createAndShowGUI() {
    //Make sure we have nice window decorations.
    JFrame.setDefaultLookAndFeelDecorated(true);

    //Create and set up the window.
    JFrame frame = new JFrame("ProgressBarDemo2");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    //Create and set up the content pane.
    JComponent newContentPane = new ProgressBarDemo2();
    newContentPane.setOpaque(true); //content panes must be opaque
    frame.setContentPane(newContentPane);

    //Display the window.
    frame.pack();
    frame.setVisible(true);
  }

  public static void main(String[] args) {
    //Schedule a job for the event-dispatching thread:
    //creating and showing this application's GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI();
      }
    });
  }
}
/**
 * This is the 3rd version of SwingWorker (also known as SwingWorker 3), an
 * abstract class that you subclass to perform GUI-related work in a dedicated
 * thread. For instructions on and examples of using this class, see:
 * 
 * http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html
 * 
 * Note that the API changed slightly in the 3rd version: You must now invoke
 * start() on the SwingWorker after creating it.
 */

abstract class SwingWorker {
  private Object value; // see getValue(), setValue()

  /**
   * Class to maintain reference to current worker thread under separate
   * synchronization control.
   */
  private static class ThreadVar {
    private Thread thread;

    ThreadVar(Thread t) {
      thread = t;
    }

    synchronized Thread get() {
      return thread;
    }

    synchronized void clear() {
      thread = null;
    }
  }

  private ThreadVar threadVar;

  /**
   * Get the value produced by the worker thread, or null if it hasn't been
   * constructed yet.
   */
  protected synchronized Object getValue() {
    return value;
  }

  /**
   * Set the value produced by worker thread
   */
  private synchronized void setValue(Object x) {
    value = x;
  }

  /**
   * Compute the value to be returned by the <code>get</code> method.
   */
  public abstract Object construct();

  /**
   * Called on the event dispatching thread (not on the worker thread) after
   * the <code>construct</code> method has returned.
   */
  public void finished() {
  }

  /**
   * A new method that interrupts the worker thread. Call this method to force
   * the worker to stop what it's doing.
   */
  public void interrupt() {
    Thread t = threadVar.get();
    if (t != null) {
      t.interrupt();
    }
    threadVar.clear();
  }

  /**
   * Return the value created by the <code>construct</code> method. Returns
   * null if either the constructing thread or the current thread was
   * interrupted before a value was produced.
   * 
   * @return the value created by the <code>construct</code> method
   */
  public Object get() {
    while (true) {
      Thread t = threadVar.get();
      if (t == null) {
        return getValue();
      }
      try {
        t.join();
      } catch (InterruptedException e) {
        Thread.currentThread().interrupt(); // propagate
        return null;
      }
    }
  }

  /**
   * Start a thread that will call the <code>construct</code> method and
   * then exit.
   */
  public SwingWorker() {
    final Runnable doFinished = new Runnable() {
      public void run() {
        finished();
      }
    };

    Runnable doConstruct = new Runnable() {
      public void run() {
        try {
          setValue(construct());
        } finally {
          threadVar.clear();
        }

        SwingUtilities.invokeLater(doFinished);
      }
    };

    Thread t = new Thread(doConstruct);
    threadVar = new ThreadVar(t);
  }

  /**
   * Start the worker thread.
   */
  public void start() {
    Thread t = threadVar.get();
    if (t != null) {
      t.start();
    }
  }
}

class LongTask {
  private int lengthOfTask;

  private int current = 0;

  private boolean done = false;

  private boolean canceled = false;

  private String statMessage;

  public LongTask() {
    //Compute length of task...
    //In a real program, this would figure out
    //the number of bytes to read or whatever.
    lengthOfTask = 1000;
  }

  /**
   * Called from ProgressBarDemo to start the task.
   */
  public void go() {
    final SwingWorker worker = new SwingWorker() {
      public Object construct() {
        current = 0;
        done = false;
        canceled = false;
        statMessage = null;
        return new ActualTask();
      }
    };
    worker.start();
  }

  /**
   * Called from ProgressBarDemo to find out how much work needs to be done.
   */
  public int getLengthOfTask() {
    return lengthOfTask;
  }

  /**
   * Called from ProgressBarDemo to find out how much has been done.
   */
  public int getCurrent() {
    return current;
  }

  public void stop() {
    canceled = true;
    statMessage = null;
  }

  /**
   * Called from ProgressBarDemo to find out if the task has completed.
   */
  public boolean isDone() {
    return done;
  }

  /**
   * Returns the most recent status message, or null if there is no current
   * status message.
   */
  public String getMessage() {
    return statMessage;
  }

  /**
   * The actual long running task. This runs in a SwingWorker thread.
   */
  class ActualTask {
    ActualTask() {
      //Fake a long task,
      //making a random amount of progress every second.
      while (!canceled && !done) {
        try {
          Thread.sleep(1000); //sleep for a second
          current += Math.random() * 100; //make some progress
          if (current >= lengthOfTask) {
            done = true;
            current = lengthOfTask;
          }
          statMessage = "Completed " + current + " out of "
              + lengthOfTask + ".";
        } catch (InterruptedException e) {
          System.out.println("ActualTask interrupted");
        }
      }
    }
  }
}

           
         
    
  








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