//: c14:Sharing2.java
// From Thinking in Java, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
// Using the synchronized keyword to prevent
// multiple access to a particular resource.
// <applet code=Sharing2m width=650 height=500>
// <param name=size value="20">
// <param name=observers value="1">
// </applet>
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

class TwoCounter2 extends Thread {
  private boolean started = false;
  private JTextField 
    t1 = new JTextField(5),
    t2 = new JTextField(5);
  private JLabel l = 
    new JLabel("count1 == count2");
  private int count1 = 0, count2 = 0;
  public TwoCounter2(Container c) {
    JPanel p = new JPanel();
    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) {
	synchronized(this) {
         t1.setText(Integer.toString(count1++));
         t2.setText(Integer.toString(count2++));
      }
      try {
        sleep(500);
      } catch (InterruptedException e){}
    }
  }
  public synchronized void synchTest() {
    Sharing2.incrementAccess();
    if(count1 != count2)
      l.setText("Unsynched");
  }
}

class Watcher2 extends Thread {
  private Sharing2 p;
  public Watcher2(Sharing2 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 Sharing2m extends JApplet {
  TwoCounter2[] s;
  private static int accessCount = 0;
  private static JTextField aCount = 
    new JTextField("0", 7);
  public static void incrementAccess() {
    accessCount++;
    aCount.setText(Integer.toString(accessCount));
  }
  private JButton 
    start = new JButton("Start"),
    observer = new JButton("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 TwoCounter2[numCounters];
    Container cp = getContentPane();
    cp.setLayout(new FlowLayout());
    for(int i = 0; i < s.length; i++)
      s[i] = new TwoCounter2(cp);
    JPanel p = new JPanel();
    start.addActionListener(new StartL());
    p.add(start);
    observer.addActionListener(new ObserverL());
    p.add(observer);
    p.add(new Label("Access Count"));
    p.add(aCount);
    cp.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 Watcher2(Sharing2.this);
    }
  }
  public static void main(String[] args) {
    Sharing2 applet = new Sharing2m();
    // 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]));
    JFrame frame = new JFrame("Sharing2");
    frame.addWindowListener(
      new WindowAdapter() {
        public void windowClosing(WindowEvent e){
          System.exit(0);
        }
      });
    frame.getContentPane().add(applet);
    frame.setSize(350, applet.numCounters * 50);
    applet.init();
    applet.start();
    frame.setVisible(true);
  }
} ///:~