因为是2个锁，所以存在安全问题，最后会有0 这个我知道。 但是为什么会有2个相同的值？

Question

class Ticket implements Runnable
{
private int num = 100;
Object obj = new Object();
boolean flag = true;
public void run()
{
if(flag)
while(true)
{
synchronized(obj)
{
if(num>0)
{
try{Thread.sleep(10);}catch (InterruptedException e){}
System.out.println(Thread.currentThread().getName()+".....obj...."+num--);
}
}
}
else
while(true)
this.show();
}

public synchronized void show()
{
if(num>0)
{
try{Thread.sleep(10);}catch (InterruptedException e){}

System.out.println(Thread.currentThread().getName()+".....function...."+num--);
}
}
}

class SynFunctionLockDemo
{
public static void main(String[] args)
{
Ticket t = new Ticket();
Thread t1 = new Thread(t);
Thread t2 = new Thread(t);
t1.start();
try{Thread.sleep(10);}catch(InterruptedException e){}
t.flag = false;
t2.start();
}
}

Answer 1

你num是各个线程自己的。你要把共享的变量定义成static