搞了很久，没搞出来
class Res
{
boolean flag = false;
}
class Input implements Runnable
{
Res r;
Input(Res r)
{
this.r = r;
}
public void run()
{
while(true)
{
if (r.flag == true)
{
synchronized(r)
{
System.out.println("in2"+".."+r.flag);
r.flag = false;
}
}
}
}
}
class Output implements Runnable
{
Res r;
Output(Res r)
{
this.r = r;
}
public void run()
{
while(true)
{
if (r.flag == false)
{
synchronized(r)
{
System.out.println("out2"+".."+r.flag);
r.flag = true;
}
}
}
}
}
class ThreadError
{
public static void main(String[] args)
{
Res r = new Res();
Input in = new Input(r);
Output out = new Output(r);
Thread t1 = new Thread(in);
Thread t2 = new Thread(out);
t1.start();
t2.start();
}
}