JUC-集合线程安全-异常演示以及ArrayList线程不安全和解决方案

本是古典何须时尚 2024-04-06 10:34 33阅读 0赞

package com.nanjing.juc;
    
    import java.util.ArrayList;
    import java.util.List;
    import java.util.UUID;
    
    /**
     * list集合线程不安全
     */
    public class ThreadDemo_07 {
        public static void main(String[] args) {
            List<String> list = new ArrayList<String>();
            for (int i = 0; i < 30; i++) {
                new Thread(()->{
                    //向集合中添加内容
                    list.add(UUID.randomUUID().toString().substring(0,8));
                    //从集合获取内容
                    System.out.println(list);
                },String.valueOf(i)).start();
            }
        }
    }

当你用多个线程，一边往里面放，一边从里面取

就会出现并发修改异常

![32f6fad8683a41ad9e68be74db5aec3d.png][]

![1ac822ab94654a64bd684e7a2aefc551.png][]

add方法并没有加任何锁

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解决方案一：

![af1c49a0426848b1a301e5a5df62944d.png][]

![a21c14c56051419aa4d0180bb9490a0e.png][]

![277e1f2439d34dfabb13dd8aef5945f2.png][]

--------------------

解决方案二：

![75d980693dc046889fb7e21e6b3f55c7.png][]

--------------------

以上两种方法都比较古老，实际开发不常用，开发还是使用JUC里面给我们提供的类

CopyOnWriteArrayList

![9066823ad6744bdc94bcdd150495133d.png][]源码：

![fec1a8e7acd14af985d41ab42feca7b3.png][]解决方法三：

![989985a3066f4a1286c43a65d0d32adf.png][]

![311b172503b7450182c2a2e165b5ba55.png][]

那怎么解决数据不一致问题呢？？

通过volatile和互斥锁来解决

详细说明：

![d9eef23a3e7348f6ace03ebf9b55952b.png][]

--------------------

![d385718f0fe24b23b2ca570bbe1f15ba.png][]![e2271a6b3a89455a8c7c98ec13189c7a.png][]

[32f6fad8683a41ad9e68be74db5aec3d.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/f46dc2d90f354a38868e151d7fa85e12.png
[1ac822ab94654a64bd684e7a2aefc551.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/92ff5ade1b5948329c09fd6d61239a7b.png
[af1c49a0426848b1a301e5a5df62944d.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/f10ca7b27dc44247a3e535fb8e6521ed.png
[a21c14c56051419aa4d0180bb9490a0e.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/0f933c72789d4b87aa7de306d575a1e2.png
[277e1f2439d34dfabb13dd8aef5945f2.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/06d7e1febd31490a8e39a6ede7dfcf36.png
[75d980693dc046889fb7e21e6b3f55c7.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/0e35d93724e04f20a5aa373426b3f33e.png
[9066823ad6744bdc94bcdd150495133d.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/2c609551de8e42f7810d79cfee63f323.png
[fec1a8e7acd14af985d41ab42feca7b3.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/ff871188787c4142ad387ec5a48fa4bf.png
[989985a3066f4a1286c43a65d0d32adf.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/0bebcdad3626477390fe20abc1701084.png
[311b172503b7450182c2a2e165b5ba55.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/f414ec20267c40d986e3e5726564eb3b.png
[d9eef23a3e7348f6ace03ebf9b55952b.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/ffd3d2f9023d4343a2c0492a4f67d5b0.png
[d385718f0fe24b23b2ca570bbe1f15ba.png]: https://img-blog.csdnimg.cn/d385718f0fe24b23b2ca570bbe1f15ba.png
[e2271a6b3a89455a8c7c98ec13189c7a.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/06/3d23d60d468447519867013442a4ac32.png