java,synchronized方法

java为防止资源冲突而提供了synchronized关键字支持，当任务要执行被synchronized关键字修饰的代码片段时，先检查锁是否可用，然后获取锁，执行代码，释放锁。

package com.zhiru;

class RwThread implements Runnable{

public synchronized void f(){
for(int i=1;i<=5;i++)
System.out.println("loop "+i);
}
@Override
public void run() {
// TODO Auto-generated method stub
System.out.println(Thread.currentThread().getName()+"start...");
f();
}

}
public class ThreadSync {

public static void main(String[] args) {
// TODO Auto-generated method stub
Runnable t=new RwThread();
Thread t1=new Thread(t,"t1");
Thread t2=new Thread(t,"t2");
t1.start();
t2.start();

}

}


若方法f未被synchronized关键字修饰结果如下：
t2start...

t1start...

loop 1

loop 1

loop 2

loop 2

loop 3

loop 3

loop 4

loop 4

loop 5

loop 5

加上synchronized关键字：

t2start...

t1start...

loop 1

loop 2

loop 3

loop 4

loop 5

loop 1

loop 2

loop 3

loop 4

loop 5