ConcurrentHashMap组合操作

对于从ConcurrentHashMap中取到的value，如果操作完之后重复对key赋新的value值，需要注意线程安全问题;使用while循环和replace方法，规避问题

public class OptionNotSafe implements Runnable {
    private static ConcurrentHashMap<String, Integer> scores = new ConcurrentHashMap<>();
    public static void main(String[] args) throws InterruptedException {
        scores.put("小明", 0);
        OptionNotSafe notSafe = new OptionNotSafe();
        Thread thread1 = new Thread(notSafe);
        Thread thread2 = new Thread(notSafe);
        thread1.start();
        thread2.start();
        thread1.join();
        thread2.join();
        System.out.println(scores);
    }
    @Override
    public void run() {
        for (int i = 0; i < 1000; i++) {
            while (true) {
                Integer score = scores.get("小明");
                int newScore = score + 1;
                boolean b = scores.replace("小明", score, newScore);
                if (b) {
                    break;
                }
            }
        }
    }
}

https://www.bilibili.com/video/BV1gT4y1V7aZ?p=32