死锁的两个例子

package Threads;

public class DielockThread extends Thread{
    static Object o1=new Object();
    static Object o2=new Object();
    boolean flag;
    public DielockThread(boolean flag){
        this.flag=flag;
    }
    @Override
    public void run() {
        if(flag==true){
            synchronized (o1){
                System.out.println("if o1");
                synchronized (o2){
                    System.out.println("if o2");
                }
            }
        }
        else{
            synchronized (o2){
                System.out.println("else o2");
                synchronized (o1){
                    System.out.println("else o1");
                }
            }
        }
    }
}

package Threads;

public class Dielock2 {
    public static void main(String[] args) {
        DielockThread d1=new DielockThread(true);
        DielockThread d2=new DielockThread(false);
        d1.start();
        d2.start();
    }
}

package Threads;

public class DieLock {
    public static void main(String[] args) {
        StringBuffer s1=new StringBuffer();
        StringBuffer s2=new StringBuffer();
        new Thread(){
            @Override
            public void run() {
                synchronized (s1){//s1有锁状态
                    s1.append("a");
                    s2.append("1");
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    synchronized (s2){//s2为有锁状态无法执行此代码块
                        s1.append("b");
                        s2.append("2");
                        System.out.println(s1);
                        System.out.println(s2);
                    }
                }
            }
        }.start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                synchronized (s2){//s2有锁状态
                    s1.append("c");
                    s2.append("3");
                    try {
                        Thread.sleep(500);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    synchronized (s1){//s1为有锁状态无法执行此代码块
                        s1.append("d");
                        s2.append("4");
                        System.out.println(s1);
                        System.out.println(s2);
                    }
                }
            }
        }).start();
    }
}

 第二个死锁状态无法输出