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;@Overridepublicvoidrun(){isRun=true;while(isRun){System.out.println("runing......");}}publicvoidstop(){this.isRun=false;}@OverridepublicStringtoString(){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;
@Override
publicvoidrun(){
System.out.println("isRunValue:"+isRun);
isRun=0;
while(isRun==0){
System.out.println("runing......");
try{
Thread.sleep(1000l);
}catch(Exceptione){
}
}
}
publicvoidstop(){
this.isRun=2;
}
@Override
publicStringtoString(){
return"Foo{"+"isRun="+isRun+"}\n";
}
}
这个时候你会看到类似这样的输出
Foo{isRun=2}
isRunValue:2
runing......
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：
@Override
publicvoidrun(){
//isRun=true;
while(isRun){
System.out.println("runing......");
}
}
isRun一开始就初始化，应该这么写：
publicclassFooThreadimplementsRunnable{
privatebooleanisRun=true;
@Override
publicvoidrun(){
System.out.println("runbegin...");
//isRun=true;
while(isRun){
System.out.println("runing......");
}
}
publicvoidstop(){
System.out.println("callstop");
this.isRun=false;
}
@Override
publicStringtoString(){
return"Foo{"+
"isRun="+isRun+
'}';
}
publicstaticvoidmain(String[]args){
FooThreadf=newFooThread();
Threadt=newThread(f);
t.start();
try{
Thread.sleep(100);
}catch(InterruptedExceptione){
//TODOAuto-generatedcatchblock
e.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......
callstop
Foo{isRun=false}