Map Key为String 取值，使用key 为Integer取值,结果为null

package com.example.core.mydemo.javatest;

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

public class MapTest {
    public static void main(String[] args) {
        Map<String,String> map = new HashMap<>();
        map.put("11","a");
        map.put("22","b");

        System.out.println("11="+map.get("11"));
        System.out.println("22="+map.get(11));

    }
}