AtomicReference 原子方式更新对象引用
举例:1000个线程,对一个Integer累加1,直到1000
启动文件
package com.jane;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;
public class Main {
public static void main(String[] args) throws InterruptedException {
AtomicReference<Integer> ref = new AtomicReference<>(new Integer(0));
List<Thread> list = new ArrayList<>();
for (int i = 0; i < 1000; i++) {
Thread t = new Thread(new Task(ref), "Thread-no" + i);
list.add(t);
t.start();
}
for (Thread t : list) {
t.join();
}
System.out.println(ref.get()); // 打印2000
}
}
Task任务
package com.jane;
import java.util.concurrent.atomic.AtomicReference;
public class Task implements Runnable {
private AtomicReference<Integer> ref;
Task(AtomicReference<Integer> ref) {
this.ref = ref;
}
@Override
public void run() {
for (; ; ) { //自旋操作
Integer oldV = ref.get();
if (ref.compareAndSet(oldV, oldV + 1)) // CAS操作
break;
}
}
}
结果
说明
AtomicReference持有一个volatile的对象引用
利用unsafe的CAS原理实现对引用对象的的无锁操作