多线程4---对象锁--脏读

1.

public class DirtyRead {
    private String username = "ck";
    private String password = "123";
    
    public  synchronized void setValue(String username, String password){
        this.username = username;
        try {
            System.out.println("线程:"+Thread.currentThread().getName()+"===>>>正在setvalue");
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        this.password = password;
        System.out.println("线程:"+Thread.currentThread().getName()+"===>>>setvalue最终结果:username="+username+"; password:"+password );
    }
    
    public  synchronized void getValue(){
        System.out.println("线程:"+Thread.currentThread().getName()+"===>>>getValue最终结果:usrname:"+username+";password:"+password);
    }
    
    public static void main(String[] args) throws Exception {
        final DirtyRead dirtyRead = new DirtyRead();
        Thread t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                dirtyRead.setValue("ckang", "456"); //对象锁dirtyRead
            }
        }, "t1");
        t1.start();
        
        Thread.sleep(1000);
        dirtyRead.getValue();
    }
    /*
     如果setValue和getValue方法不加sychronized, t1休息2s的时候被main抢了cpu.
     线程:t1===>>>正在setvalue
    线程:main===>>>getValue最终结果:usrname:ckang;password:123
    线程:t1===>>>setvalue最终结果:username=ckang; password:456 
    
    如果set/get方法加了synchronized, 谁抢到cpu必须等执行完释放锁,才会切换到另外一个线程
    线程:t1===>>>正在setvalue
    线程:t1===>>>setvalue最终结果:username=ckang; password:456 
    线程:main===>>>getValue最终结果:usrname:ckang;password:456
     */
}