如何在HashMap中演示竞争条件？

import java.util.HashMap;

public class HashMapConcurrencyExample {
    public static void main(String[] args) {
        final HashMap<Integer, String> map = new HashMap<>();

        // 创建两个线程同时向HashMap中添加元素
        Thread thread1 = new Thread(() -> {
            for (int i = 0; i < 1000; i++) {
                map.put(i, "Value" + i);
            }
        });

        Thread thread2 = new Thread(() -> {
            for (int i = 1000; i < 2000; i++) {
                map.put(i, "Value" + i);
            }
        });

        thread1.start();
        thread2.start();

        // 等待两个线程执行完毕
        try {
            thread1.join();
            thread2.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        // 输出HashMap的大小
        System.out.println("HashMap size: " + map.size());
    }
}