public?class?FlagWork?{
????public?static?void?main(String[]?args)?{
????????final?Business1?b1?=?new?Business1();
????????new?Thread(new?Runnable()?{
?
????????????@Override
????????????public?void?run()?{
????????????????b1.a();
????????????}
????????}).start();
????????new?Thread(new?Runnable()?{
?
????????????@Override
????????????public?void?run()?{
????????????????b1.b();
????????????}
????????}).start();
????????new?Thread(new?Runnable()?{
?????????????
????????????@Override
????????????public?void?run()?{
????????????????b1.c();
????????????}
????????}).start();
????}
}
?
class?Business1?{
????private?int?flag?=?1;
?
????public?void?a()?{
????????for?(int?i?=?0;?i?<?50;?i++)?{
????????????synchronized?(this)?{
????????????????while?(flag?!=?1)?{
????????????????????try?{
????????????????????????this.wait();
????????????????????}?catch?(InterruptedException?e)?{
????????????????????????//?TODO?Auto-generated?catch?block
????????????????????????e.printStackTrace();
????????????????????}
????????????????}
????????????????for?(int?j?=?1;?j?<=?10;?j++)?{
????????????????????System.out.println("線程a運行"?+?j?+?"次");
????????????????}
????????????????flag?=?2;
????????????????this.notify();
????????????}
????????}
????}
?
????public?void?b()?{
????????for?(int?i?=?0;?i?<?50;?i++)?{
????????????synchronized?(this)?{
????????????????while?(flag?!=?2)?{
????????????????????try?{
????????????????????????this.wait();
????????????????????}?catch?(InterruptedException?e)?{
????????????????????????//?TODO?Auto-generated?catch?block
????????????????????????e.printStackTrace();
????????????????????}
????????????????}
????????????????for?(int?j?=?1;?j?<=?20;?j++)?{
????????????????????System.out.println("線程b運行"?+?j?+?"次");
????????????????}
????????????????flag?=?3;
????????????????this.notify();
????????????}
????????}
????}
????public?void?c()?{
????????for?(int?i?=?0;?i?<?50;?i++)?{
????????????synchronized(this){
????????????????while(flag!=3){
????????????????????try?{
????????????????????????this.wait();
????????????????????}?catch?(InterruptedException?e)?{
????????????????????????//?TODO?Auto-generated?catch?block
????????????????????????e.printStackTrace();
????????????????????}
????????????????}
????????????????for?(int?j?=?1;?j?<=?30;?j++)?{
????????????????????System.out.println("線程c運行"+j+"次");
????????????????}
????????????????flag?=?1;
????????????????this.notifyAll();
????????????}
????????}
????}
}

A線程先運行10次，然后B線程運行20次，然后C線程運行30次，如此反復50次的代碼，為什么次c方法里要用this.notifyAll，而用this.notify就不行