Reverse Code Engineering RCE CD +sandman 2000/ReverseCodeEngineeringRceCdsandman2000.iso/RCE/Ebooks/Thinking in Java/c14/Sharing1.java

Java Source | 2000-05-25 | 5.8 KB | 181 lines

//: Sharing1.java
//////////////////////////////////////////////////
// Copyright (c) Bruce Eckel, 1998
// Source code file from the book "Thinking in Java"
// All rights reserved EXCEPT as allowed by the
// following statements: You can freely use this file
// for your own work (personal or commercial),
// including modifications and distribution in
// executable form only. Permission is granted to use
// this file in classroom situations, including its
// use in presentation materials, as long as the book
// "Thinking in Java" is cited as the source.
// Except in classroom situations, you cannot copy
// and distribute this code; instead, the sole
// distribution point is http://www.BruceEckel.com
// (and official mirror sites) where it is
// freely available. You cannot remove this
// copyright and notice. You cannot distribute
// modified versions of the source code in this
// package. You cannot use this file in printed
// media without the express permission of the
// author. Bruce Eckel makes no representation about
// the suitability of this software for any purpose.
// It is provided "as is" without express or implied
// warranty of any kind, including any implied
// warranty of merchantability, fitness for a
// particular purpose or non-infringement. The entire
// risk as to the quality and performance of the
// software is with you. Bruce Eckel and the
// publisher shall not be liable for any damages
// suffered by you or any third party as a result of
// using or distributing software. In no event will
// Bruce Eckel or the publisher be liable for any
// lost revenue, profit, or data, or for direct,
// indirect, special, consequential, incidental, or
// punitive damages, however caused and regardless of
// the theory of liability, arising out of the use of
// or inability to use software, even if Bruce Eckel
// and the publisher have been advised of the
// possibility of such damages. Should the software
// prove defective, you assume the cost of all
// necessary servicing, repair, or correction. If you
// think you've found an error, please email all
// modified files with clearly commented changes to:
// [e-mail]. (Please use the same
// address for non-code errors found in the book.)
/////////////////////////////////////////////////

// Problems with resource sharing while threading
import java.awt.*;
import java.awt.event.*;
import java.applet.*;

class TwoCounter extends Thread {
  private boolean started = false;
  private TextField
    t1 = new TextField(5),
    t2 = new TextField(5);
  private Label l =
    new Label("count1 == count2");
  private int count1 = 0, count2 = 0;
  // Add the display components as a panel
  // to the given container:
  public TwoCounter(Container c) {
    Panel p = new Panel();
    p.add(t1);
    p.add(t2);
    p.add(l);
    c.add(p);
  }
  public void start() {
    if(!started) {
      started = true;
      super.start();
    }
  }
  public void run() {
    while (true) {
      t1.setText(Integer.toString(count1++));
      t2.setText(Integer.toString(count2++));
      try {
        sleep(500);
      } catch (InterruptedException e){}
    }
  }
  public void synchTest() {
    Sharing1.incrementAccess();
    if(count1 != count2)
      l.setText("Unsynched");
  }
}

class Watcher extends Thread {
  private Sharing1 p;
  public Watcher(Sharing1 p) {
    this.p = p;
    start();
  }
  public void run() {
    while(true) {
      for(int i = 0; i < p.s.length; i++)
        p.s[i].synchTest();
      try {
        sleep(500);
      } catch (InterruptedException e){}
    }
  }
}

public class Sharing1 extends Applet {
  TwoCounter[] s;
  private static int accessCount = 0;
  private static TextField aCount =
    new TextField("0", 10);
  public static void incrementAccess() {
    accessCount++;
    aCount.setText(Integer.toString(accessCount));
  }
  private Button
    start = new Button("Start"),
    observer = new Button("Observe");
  private boolean isApplet = true;
  private int numCounters = 0;
  private int numObservers = 0;
  public void init() {
    if(isApplet) {
      numCounters =
        Integer.parseInt(getParameter("size"));
      numObservers =
        Integer.parseInt(
          getParameter("observers"));
    }
    s = new TwoCounter[numCounters];
    for(int i = 0; i < s.length; i++)
      s[i] = new TwoCounter(this);
    Panel p = new Panel();
    start.addActionListener(new StartL());
    p.add(start);
    observer.addActionListener(new ObserverL());
    p.add(observer);
    p.add(new Label("Access Count"));
    p.add(aCount);
    add(p);
  }
  class StartL implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      for(int i = 0; i < s.length; i++)
        s[i].start();
    }
  }
  class ObserverL implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      for(int i = 0; i < numObservers; i++)
        new Watcher(Sharing1.this);
    }
  }
  public static void main(String[] args) {
    Sharing1 applet = new Sharing1();
    // This isn't an applet, so set the flag and
    // produce the parameter values from args:
    applet.isApplet = false;
    applet.numCounters =
      (args.length == 0 ? 5 :
        Integer.parseInt(args[0]));
    applet.numObservers =
      (args.length < 2 ? 5 :
        Integer.parseInt(args[1]));
    Frame aFrame = new Frame("Sharing1");
    aFrame.addWindowListener(
      new WindowAdapter() {
        public void windowClosing(WindowEvent e){
          System.exit(0);
        }
      });
    aFrame.add(applet, BorderLayout.CENTER);
    aFrame.setSize(350, applet.numCounters *100);
    applet.init();
    applet.start();
    aFrame.setVisible(true);
  }
} ///:~