Suspend.java

//: c14:Suspend.java
// From 'Thinking in Java, 2nd ed.' by Bruce Eckel
// www.BruceEckel.com. See copyright notice in CopyRight.txt.
// The alternative approach to using suspend()
// and resume(), which are deprecated in Java 2.
// <applet code=Suspend width=300 height=100>
// </applet>
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import com.bruceeckel.swing.*;

public class Suspend extends JApplet {
  private JTextField txt = new JTextField(10);
  private JButton 
    suspendB = new JButton("Suspend"),
    resumeB = new JButton("Resume");
  private int SuspendCount = 1;
  private Suspendable ssT = new Suspendable();
  class Suspendable extends Thread {
    private int count = 0;
    private boolean suspendedF = false;
    public Suspendable() { start(); }

    public void funSuspend() { 
      suspendedF = true;
    }

    public synchronized void funResume() {
      suspendedF = false;
      notify();
    }
    public void run() {
      while (true) {
        try {
          sleep(500);
          synchronized(this) {
            while(suspendedF) {
              txt.setText("Suspend #: " +  SuspendCount++);
              wait();
            }
          }
        } catch(InterruptedException e) {
          System.err.println("Interrupted");
        }
        txt.setText(Integer.toString(count++));
      }
    }
  } 
  public void init() {
    Container cp = getContentPane();
    cp.setLayout(new FlowLayout());
    cp.add(txt);

    suspendB.addActionListener(
      new ActionListener() {
        public 
        void actionPerformed(ActionEvent e) {
          ssT.funSuspend();
          suspendB.setEnabled(false);
          suspendB.setBackground(Color.red);
          resumeB.setEnabled(true);
          resumeB.setBackground(Color.green);
        }
      });
    cp.add(suspendB);
    suspendB.setEnabled(true);
    suspendB.setBackground(Color.green);

    resumeB.addActionListener(
      new ActionListener() {
        public 
        void actionPerformed(ActionEvent e) {
          ssT.funResume();
          suspendB.setEnabled(true);
          suspendB.setBackground(Color.green);
          resumeB.setEnabled(false);
          resumeB.setBackground(Color.red);
        }
      });
    cp.add(resumeB);
    resumeB.setEnabled(false);
    resumeB.setBackground(Color.red);
  }
  public static void main(String[] args) {
    Console.run(new Suspend(), 300, 100);
  }
} ///:
} ///:~