先说同步方法。它究竟是锁定的当前对象,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

java线程同步方法,方法块差别-LMLPHP

由此可见是当前对象,而A和B是两个不同的对象。所以打印序列就是混乱的

代码块2

看同步块

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

java线程同步方法,方法块差别-LMLPHP

说明同步块能够锁定不论什么对象

就是说同步方法是锁定当前对象,同步方法块是能够锁定不论什么对象

05-26 03:55