关于对synchronized的理解

 当一个线程进入一个对象的一个synchronized方法后，其它线程是否可进入此对象的其它方法?

今天在论坛中看见这道题，开始也很模糊，最后写了个程序得出如下答案。

如果是同步方法的话是不可以的。
如果是非同步方法的话是可以的。
下面贴出代码：

package Test;public class Test1{public static void main(String[] args){ThreadDemo threadDemo=new ThreadDemo();Thread t1=new ThreadOne(threadDemo);Thread t2=new ThreadTwo(threadDemo);Thread t3=new ThreadThree(threadDemo);t1.start();t2.start();t3.start();}}class ThreadDemo{public synchronized void method1(){for (int i = 0; i < 10; i++){try{Thread.sleep(500);} catch (InterruptedException e){e.printStackTrace();}System.out.println("同步方法1"+"    "+ i);}}public synchronized void method2(){for (int i = 0; i < 10; i++){try{Thread.sleep(500);} catch (InterruptedException e){e.printStackTrace();}System.out.println("同步方法2"+"    " + i);}}public void Print(){for (int i = 0; i < 10; i++){try{Thread.sleep(500);} catch (InterruptedException e){e.printStackTrace();}System.out.println("非同步方法" + i);}}}class ThreadOne extends Thread{private ThreadDemo threadDemo;public ThreadOne(ThreadDemo threadDemo){this.threadDemo = threadDemo;}public void run(){this.threadDemo.method1();}}class ThreadTwo extends Thread{private ThreadDemo threadDemo;public ThreadTwo(ThreadDemo threadDemo){this.threadDemo = threadDemo;}public void run(){this.threadDemo.method2();}}class ThreadThree extends Thread{private ThreadDemo threadDemo;public ThreadThree(ThreadDemo threadDemo){this.threadDemo = threadDemo;}public void run(){this.threadDemo.Print();}}

定义ThreadDemo类 有三个方法metho1，method2，Print。
其中metho1，method2为同步方法。Print为非同步方法。
如果在主函数中只开启t1.start()和t2.start();则输出结果为
t1输出完后，t2在输出。所以如果是同步方法的话是不可以的。

如果在主函数中只开启t1.start()和t3.start();则输出结果为
t1，Print交替输出。所以如果是非同步方法的话是可以的。

---------------------- android培训、java培训、期待与您交流！ ----------------------