<转：/uniquewonderq/article/details/48113071>
程序举例：
代码：
[java]view plaincopy packagecom.synch;publicclassSynchronizedDemo{//共享变量privatebooleanready=false;privateintresult=0;privateintnumber=1;//写操作publicsynchronizedvoidwrite(){ready=true;number=2;}//读操作publicsynchronizedvoidread(){if(ready){result=number*3;}System.out.println("result的值为："+result);}//内部线程类privateclassReadWriteThreadextendsThread{//根据构造方法中传入的flag参数，确定线程执行读操作还是写操作privatebooleanflag;publicReadWriteThread(booleanflag){this.flag=flag;}@Overridepublicvoidrun(){if(flag){//构造方法中传入true，执行写操作write();}else{//构造方法中传入false，执行读操作read();}}}publicstaticvoidmain(String[]args){SynchronizedDemosynDemo=newSynchronizedDemo();//启动线程执行写操作synDemo.newReadWriteThread(true).start();//try{//Thread.sleep(1000);//}catch(InterruptedExceptione){////TODOAuto-generatedcatchblock//e.printStackTrace();//}//启动线程执行读操作synDemo.newReadWriteThread(false).start();}}
代码示例：
[java]view plaincopy packagecom.synch;importjava.util.concurrent.locks.Lock;importjava.util.concurrent.locks.ReentrantLock;publicclassVolatileDemo{privateLocklock=newReentrantLock();privateintnumber=0;publicintgetNumber(){returnthis.number;}publicvoidincrease(){try{Thread.sleep(100);}catch(InterruptedExceptione){//TODOAuto-generatedcatchblocke.printStackTrace();}lock.lock();try{this.number++;}finally{lock.unlock();}}/***@paramargs*/publicstaticvoidmain(String[]args){//TODOAuto-generatedmethodstubfinalVolatileDemovolDemo=newVolatileDemo();for(inti=0;i<500;i++){newThread(newRunnable(){@Overridepublicvoidrun(){volDemo.increase();}}).start();}//如果还有子线程在运行，主线程就让出CPU资源，//直到所有的子线程都运行完了，主线程再继续往下执行while(Thread.activeCount()>1){//让所有的子线程都执行完后，然后再执行<prename="code"class="java">//System.out.println("number:"+volDemo.getNumber());语句。因为主线程算一个。当活跃线程为1时，也就是所有的子线程执行完毕了。此///时退出while循环执行输出语句。 Thread.yield();}System.out.println("number : " + volDemo.getNumber());}}
