java多线程详解六 多线程死锁问题

多线程死锁问题：

1.出现的原因：

有两个线程t1和t2，两把锁locka 和lockb，t1拿着locka去拿lockb,t2拿着lockb去拿locka就会出现死锁问题。

public class DeadLockDemo {
public static void main(String[] args) {
   DeadLock deadLock1=new DeadLock(true);
   DeadLock deadLock2=new DeadLock(false);
   Thread thread1=new Thread(deadLock1);
   Thread thread2=new Thread(deadLock2);
   thread1.start();
   thread2.start();
  }
}

class DeadLock implements Runnable{
   private boolean flag;
   public DeadLock(boolean flag) {
   this.flag=flag;
}

@Override
public void run() {
   if (flag){
   while (true) {
     synchronized (MyLock.locka) {
     System.out.println("if.....locka");
     synchronized (MyLock.lockb) {
     System.out.println("if.....lockb");
      }
    }
   }
}else {
   while (true) {
   synchronized (MyLock.lockb) {
   System.out.println("else.....lockb");
   synchronized (MyLock.locka) {
    System.out.println("else.....locka");
      }
     }
   }
  }
 }
}

class MyLock{
   public static MyLock locka=new MyLock();
   public static MyLock lockb=new MyLock();
}