java-synchronized 嵌套使用代码详解

当synchronized使用过多时，可能会造成死锁，那么死锁到底是怎么一回事呢。先看下面的代码，实现死锁：

//死锁的实现classA{publicvoidget(){System.out.println("A说:我开始启动了，B，给我你的资源");}publicvoidsay(){System.out.println("A获得资源");}}classB{publicvoidget(){System.out.println("B说:我开始启动了，A，给我你的资源");}publicvoidsay(){System.out.println("B获得资源");}}claSSMyThreadimplementsRunnable{publicstaticAa=newA();publicstaticBb=newB();publicbooleanflag=false;publicvoidrun(){if(flag){synchronized(a){a.get();try{Thread.sleep(500);}catch(InterruptedExceptione){}synchronized(b){ //此同步代码块在另一同步代码块里a.say();}}}else{synchronized(b){b.get();try{Thread.sleep(500);}catch(InterruptedExceptione){}synchronized(a){ //此同步代码块在另一同步代码块里b.say();}}}}}publicclassDemo24{publicstaticvoidmain(Stringargs[]){MyThreadmt1=newMyThread();MyThreadmt2=newMyThread();mt1.flag=true;mt2.flag=false;Threadth2=newThread(mt1);Threadth3=newThread(mt2);th2.start();th3.start();}}