AtomicInteger效率

package com.jdk5.thread.AtomicInteger;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * Created by Vincent on 2014/8/6.
 */
public class Demo1 {

    public static void main(String[] args) throws InterruptedException {
        SameDemo sameDemo = new SameDemo();
        System.out.println(sameDemo.getI());
        long time1 = System.currentTimeMillis();
        Thread t1 = new Thread(new Thread1(sameDemo));
        Thread t2 = new Thread(new Thread2(sameDemo));
        t1.start();
        t2.start();
        t1.join();
        t2.join();
        long time2 = System.currentTimeMillis();
        System.out.println(time2-time1);
        System.out.println(sameDemo.getI());
    }
}

class SameDemo {
    private int i = 1000;

    public int getI() {
      return i;
    }

    public void setI(int i) {
      this.i=i;
    }

    public void add() {
       i+=1;
    }

    public void dec() {
       i-=1;
    }
}

class Thread1 implements Runnable {

    private SameDemo sameDemo;

    Thread1(SameDemo sameDemo) {
        this.sameDemo = sameDemo;
    }

    @Override
    public void run() {
        for (int i = 0; i < 100000000; i++) {

            sameDemo.add();
        }
    }
}

class Thread2 implements Runnable {

    private SameDemo sameDemo;

    Thread2(SameDemo sameDemo) {
        this.sameDemo = sameDemo;
    }

    @Override
    public void run() {
        for (int i = 0; i < 100000000; i++) {
            sameDemo.dec();
        }
    }
}

package com.jdk5.thread.AtomicInteger;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * Created by Vincent on 2014/8/6.
 */
public class Demo1 {

    public static void main(String[] args) throws InterruptedException {
        SameDemo sameDemo = new SameDemo();
        System.out.println(sameDemo.getI());
        long time1 = System.currentTimeMillis();
        Thread t1 = new Thread(new Thread1(sameDemo));
        Thread t2 = new Thread(new Thread2(sameDemo));
        t1.start();
        t2.start();
        t1.join();
        t2.join();
        long time2 = System.currentTimeMillis();
        System.out.println(time2-time1);
        System.out.println(sameDemo.getI());
    }
}

class SameDemo {
    private AtomicInteger i = new AtomicInteger(1000);

    public int getI() {
      return i.get();
    }

    public void setI(int i) {
       this.i.set(i);
    }

    public void add() {
        this.i.incrementAndGet();
    }

    public void dec() {
        this.i.decrementAndGet();
    }
}

class Thread1 implements Runnable {

    private SameDemo sameDemo;

    Thread1(SameDemo sameDemo) {
        this.sameDemo = sameDemo;
    }

    @Override
    public void run() {
        for (int i = 0; i < 100000000; i++) {

            sameDemo.add();
        }
    }
}

class Thread2 implements Runnable {

    private SameDemo sameDemo;

    Thread2(SameDemo sameDemo) {
        this.sameDemo = sameDemo;
    }

    @Override
    public void run() {
        for (int i = 0; i < 100000000; i++) {
            sameDemo.dec();
        }
    }
}

AtomicInteger平均时间8500ms左右，纯粹的int大约8ms左右，也就是说AtomicInteger虽然保证了线程安全，但效率低了1000倍之多