java线程同步方法，方法块区别

先说同步方法，它到底是锁定的当前对象，还是当前类

代码块1

package com.ssss;

public class Thread1 implements Runnable {  
	//public static Object  o=new Object();

    public void run() {
    	pt();
    }
    
    public synchronized void pt(){
    	int a=0;
        //synchronized(o) {  
             for (int i = 0; i < 5; i++) {
           	  a++;
           	  try {
					Thread.sleep(1000);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
                  System.out.println(Thread.currentThread().getName() + " synchronized loop " + i + "++++" + a);  
             }  
        //}  
    }
    
    
    public static void main(String[] args) {  
         Thread1 t1 = new Thread1();  
         Thread1 t2 = new Thread1();  

         Thread ta = new Thread(t1, "A");  
         Thread tb = new Thread(t2, "B");  
         ta.start();  
         tb.start();  
    } 
}

打印出来的结果为

< http://www.2cto.com/kf/ware/vc/" target="_blank" class="keylink">vcD4KPHA+tPrC67/pMjwvcD4KPHA+v7TNrLK9v+k8L3A+CjxwPjwvcD4KPHByZSBjbGFzcz0="brush:java;">package com.ssss; public class Thread1 implements Runnable { public static Object o=new Object(); public void run() { pt(); } public void pt(){ int a=0; synchronized(o) { for (int i = 0; i < 5; i++) { a++; try { Thread.sleep(1000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.println(Thread.currentThread().getName() + " synchronized loop " + i + "++++" + a); } } } public static void main(String[] args) { Thread1 t1 = new Thread1(); Thread1 t2 = new Thread1(); Thread ta = new Thread(t1, "A"); Thread tb = new Thread(t2, "B"); ta.start(); tb.start(); } }
看打印序列

说明同步块可以锁定任何对象

就是说同步方法是锁定当前对象，同步方法块是可以锁定任何对象