小编tao*_*ang的帖子

import java.util.HashMap;
import java.util.Map;

public class MainTest
{
    static Map<String, Integer> map = new HashMap();

    public static void incr()
    {
        map.merge("counter", 1, Integer::sum);
    }

    public static void decr()
    {
        map.merge("counter", -1, Integer::sum);
    }

    public static void main(String[] args) throws Exception
    {
        map.put("counter", 0);
        for (int i = 0; i < 10000; i++)
        {
            Thread t1 = new Thread(new Runnable()
            {
                @Override
                public void run()
                {
                    incr();
                }
            });
            t1.join();
            t1.start();

            Thread t2 = new Thread(new Runnable()
            {
                @Override
                public void …