如何在 java 中替换 List<map> 映射键的值答案

【问题标题】：How can i replace List<map> map key's value in java如何在 java 中替换 List<map> 映射键的值
【发布时间】：2021-02-08 10:07:42
【问题描述】：

我想在这里替换所有迭代的时间值

List<Map<String,Object>> mapList=new ArrayList<Map<String,Object>>();
Map myMap1=new HashMap();
myMap1.put("name", "jai");
myMap1.put("time", Instant.now());
mapList.add(myMap1);
Map myMap2=new HashMap();
myMap2.put("name", "kishan");
myMap2.put("time", Instant.now());

【问题讨论】：

标签： java list dictionary collections

【解决方案1】：

我得到了答案

import java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class HelloWorld {

    public static void main(String... args) {
        List<Map<String,Object>> mapList=new ArrayList<Map<String,Object>>();
        Map<String, Object> myMap1=new HashMap<String, Object>();
        myMap1.put("name", "jai");
        myMap1.put("time", Instant.now());
        mapList.add(myMap1);
        Map<String, Object> myMap2=new HashMap<String, Object>();
        myMap2.put("name", "kishan");
        myMap2.put("time", Instant.now());
        mapList.add(myMap2);
        System.out.println(mapList);
        mapList.forEach(oneMap -> replaceKeyBy(oneMap));
        System.out.println(mapList);
        
        }
    private static void replaceKeyBy(Map<String, Object> map) {
        map.replace("time",Instant.now().plus(10, ChronoUnit.DAYS));
    }
}

【讨论】：

【解决方案2】：

使用remove("time")返回旧值并放入新键

mapList.forEach(map ->{
    map.put("new time",map.remove("time"));
});

【讨论】：