class A
{
   public synchronized void foo( B b )
   {
      System.out.println("當(dāng)前線程名: " + Thread.currentThread().getName()
        + " 進(jìn)入了A實(shí)例的foo()方法" );   // ①
      try
      {
        Thread.sleep(200);
      }
      catch (InterruptedException ex)
      {
        ex.printStackTrace();
      }
      System.out.println("當(dāng)前線程名: " + Thread.currentThread().getName()
        + " 企圖調(diào)用B實(shí)例的last()方法");  // ③
      b.last();
   }
   public synchronized void last()
   {
      System.out.println("進(jìn)入了A類的last()方法內(nèi)部");
   }
}
class B
{
   public synchronized void bar( A a )
   {
      System.out.println("當(dāng)前線程名: " + Thread.currentThread().getName()
        + " 進(jìn)入了B實(shí)例的bar()方法" );  // ②
      try
      {
        Thread.sleep(200);
      }
      catch (InterruptedException ex)
      {
        ex.printStackTrace();
      }
      System.out.println("當(dāng)前線程名: " + Thread.currentThread().getName()
        + " 企圖調(diào)用A實(shí)例的last()方法"); // ④
      a.last();
   }
   public synchronized void last()
   {
      System.out.println("進(jìn)入了B類的last()方法內(nèi)部");
   }
}
public class DeadLock implements Runnable
{
   A a = new A();
   B b = new B();
   public void init()
   {
      Thread.currentThread().setName("主線程");
      // 調(diào)用a對(duì)象的foo方法
      a.foo(b);
      System.out.println("進(jìn)入了主線程之后");
   }
   public void run()
   {
      Thread.currentThread().setName("副線程");
      // 調(diào)用b對(duì)象的bar方法
      b.bar(a);
      System.out.println("進(jìn)入了副線程之后");
   }
   public static void main(String[] args)
   {
      DeadLock dl = new DeadLock();
      // 以dl為target啟動(dòng)新線程
      new Thread(dl).start();
      // 調(diào)用init()方法
      dl.init();
   }
}