java线程问题，直接看代码吧。不好描述。

Question

Foo类实现了Runnable接口
publicclassFooimplementsRunnable{
privatebooleanisRun;
@Override
publicvoidrun(){
isRun=true;
while(isRun){
System.out.println("runing......");
}
}
publicvoidstop(){
this.isRun=false;
}
@Override
publicStringtoString(){
return"Foo{"+
"isRun="+isRun+
'}';
}
}
测试类
publicclassThreadTest{
publicstaticvoidmain(String[]args){
Foof=newFoo();
Threadt=newThread(f);
t.start();
f.stop();
System.out.print(f);
}
}
为什么执行了stop()方法之后，t线程没有停止执行呢。
我debug发现thread在运行start()方法之前，里面的Foo对象和执行stop（）方法的Foo对象是同一个。按理说执行stop（）方法后。f的isRun被设置成了false,线程读取到该变量变成false应该停止才对。
看thread的源码
求大神解答。

Answer 1

t.start();并不是离开执行run方法，而是交给OS去调度。针对你这个例子，执行的顺序是f.stop()-->System.out.print(f)也及时调用f对象的toString，然后才开始线程执行。而在你的run方法中又设置isRun=true;所以线程无法停止。修改Foo如下：publicclassFooimplementsRunnable{privateintisRun=1;@Overridepublicvoidrun(){System.out.println("isRunValue:"+isRun);isRun=0;while(isRun==0){System.out.println("runing......");try{Thread.sleep(1000l);}catch(Exceptione){}}}publicvoidstop(){this.isRun=2;}@OverridepublicStringtoString(){return"Foo{"+"isRun="+isRun+"}\n";}}这个时候你会看到类似这样的输出Foo{isRun=2}isRunValue:2runing......runing......runing......runing......说明stop确实在run之前先执行

Answer 2

因为你这是死循环while(isRun){System.out.println("runing......");}而且isRun一直是true，你应该改成：@Overridepublicvoidrun(){//isRun=true;while(isRun){System.out.println("runing......");}}isRun一开始就初始化，应该这么写：publicclassFooThreadimplementsRunnable{privatebooleanisRun=true;@Overridepublicvoidrun(){System.out.println("runbegin...");//isRun=true;while(isRun){System.out.println("runing......");}}publicvoidstop(){System.out.println("callstop");this.isRun=false;}@OverridepublicStringtoString(){return"Foo{"+"isRun="+isRun+'}';}publicstaticvoidmain(String[]args){FooThreadf=newFooThread();Threadt=newThread(f);t.start();try{Thread.sleep(100);}catch(InterruptedExceptione){//TODOAuto-generatedcatchblocke.printStackTrace();}f.stop();System.out.print(f);}}最终输出：runing......runing......runing......runing......runing......runing......runing......runing......runing......runing......runing......runing......runing......runing......runing......runing......runing......runing......callstopFoo{isRun=false}