deadlock.java

java关于多线程的课堂练习

/**
 * @(#)DeadLock.java
 *
 *
 * @author 
 * @version 1.00 2007/12/1
 */
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

class Win extends JFrame implements Runnable{
 JPanel p1,p2; 
 JLabel lab1,lab2;
 JTextArea  text1,text2;
 Thread  trdA,trdB;
 private int accounts[]={1000,1000};
 Win() {
  setLayout(new GridLayout(2,1));
  p1=new JPanel();
  p1.setLayout(new BorderLayout());
  lab1=new JLabel("Account Information");
  text1=new JTextArea(5,40);
  p1.add(lab1,BorderLayout.NORTH);
  p1.add(new JScrollPane(text1),BorderLayout.CENTER);
  p2=new JPanel();
  p2.setLayout(new BorderLayout());
  lab2=new JLabel("Thread Information");
  text2=new JTextArea(5,40);
  p2.add(lab2,BorderLayout.NORTH);
  p2.add(new JScrollPane(text2),BorderLayout.CENTER);
  add(p1);  add(p2);
  
  trdA=new Thread(this);
  trdA.setName("A");
  trdB=new Thread(this);
  trdB.setName("B");
  trdA.start();
  trdB.start();
  
  setSize(400,700);
  setVisible(true);
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  validate();
 }
 public void run() {
 	while (true) {
 	 int amount=(int) (1500*Math.random());
 	 String s1=Thread.currentThread().getName();
 	 String s2=(s1.equals("A")?"B":"A");
 	 text2.append("Thread "+s1+" sends $"+amount+" into "+s2+"\n");
 	 System.out.println("Thread "+s1+" sends $"+amount+" into "+s2+"\n");
 	 try {
 	  //System.out.println(s1+"开始休息...");
 	  Thread.sleep(20);
 	  //System.out.println(s1+"醒来了!");
 	 }
 	 catch (InterruptedException ie) {
 	 	System.err.println("interruption in sleeping"+ie);
 	 }
 	 //System.out.println(s1+"开始转账...");
 	 transfer(amount);
 	 //System.out.println(s1+"转帐完毕!");
 	}
 }
 public synchronized void transfer(int amount) {
 	text1.append("Account A: $"+accounts[0]+"\n");
 	text1.append("Account B: $"+accounts[1]+"\n");
 	String s1=Thread.currentThread().getName();
 	String s2=(s1.equals("A")?"B":"A");
 	int from=(s1.equals("A")?0:1);
 	int into=1-from;
 	text1.append("=> $"+amount+" from"+s1+" to "+s2+"\n");
 	while (accounts[from]<amount) {
 	  try {
 	  	System.out.println(s1+"由于金额少所以等待...");
 	  	wait();
 	  	System.out.println(s1+"金额够了,被唤醒");
 	  }
 	  catch (InterruptedException ie) {
 	  	System.err.println("Error: "+ie);
 	  }
 	}
 	accounts[from]-=amount;
 	accounts[into]+=amount;
 	notify();
 }
  
  
  
  
  
 }

public class DeadLock {
        
    /**
     * Creates a new instance of <code>DeadLock</code>.
     */
    public DeadLock() {
    }
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
       new Win();
    }
}