a simple example with a potential dead

/*
 * Copyright@ 2011 www.egtry.com
 */

package egtry.thread;
/**
Potential deadlock occurs if
1. Two or more shared resources
2. Thead1 hold resource1 and need resource 2, and Thread2 hold resource2 and need resource 1


 *
 */

public class Deadlock extends Thread {
  private Account from;
  private Account to;
  private int amount;
  
  public static void main(String[] args) {
	  Account a1=new Account(100);
	  Account a2=new Account(200);
	  Deadlock t1=new Deadlock(a1,a2,10);
	  Deadlock t2=new Deadlock(a2,a1,20);
	  t1.start();
	  t2.start();
    
	  System.out.println("Done");
  }
  
  public Deadlock(Account from, Account to, int amount) {
	  this.from=from;
	  this.to=to;
	  this.amount=amount;
  }
  
  @Override
  public void run() {
	  synchronized (from) {
		  synchronized (to) {
			  from.balance -=amount;
			  to.balance +=amount;
		  }
	  }
  }
  
  public static class Account {
	  public int balance;
	  public Account(int balance) {
		  this.balance=balance;
	  }
  }
}

Done