案例

10个线程并发累加一个整数，每个线程累加1000，保证线程安全

Unsafe类，来源于sun.misc包。该类封装了许多类似指针操作，可以直接进行内存管理、操纵对象、阻塞/唤醒线程等操作。

package com.jane;

import java.util.ArrayList;

import java.util.List;

import java.util.concurrent.atomic.AtomicInteger;

public class Main {

public static void main(String[] args) throws InterruptedException {

AtomicInteger ai = new AtomicInteger();

List list = new ArrayList<>();

for (int i = 0; i < 10; i++) {

Thread t = new Thread(new Accumlator(ai), "thread-" + i);

list.add(t);

t.start();

}

for (Thread t : list) {

t.join();

}

System.out.println(ai);

}

static class Accumlator implements Runnable {

private AtomicInteger ai;

Accumlator(AtomicInteger ai) {

this.ai = ai;

}

@Override

public void run() {

for (int i = 0, len = 1000; i < len; i++) {

ai.incrementAndGet();

}

}

}

}

运行结果