【Java List与Map】List＜T＞ Map与Map List＜T＞的区别（126）

List＜T＞ Map：List里面的数据类型包含Map；
Map List＜T＞：Map里面value的数据类型包含List；

测试案例：

import java.util.ArrayList;import java.util.HashMap;import java.util.Iterator;import java.util.List;import java.util.Map;public class day20 {public static void main(String[] args) {Map<String,Object> map1 = new HashMap<>();map1.put("name","小婷");map1.put("age",20);Map<String,Object> map2 = new HashMap<>();map2.put("name","小霞");map2.put("age",22);Map<String,Object> map3 = new HashMap<>();map3.put("name","小桐");map3.put("age",24);// Map集合：List>:List<Map<String,Object>> list = new ArrayList<>();list.add(map1);list.add(map2);list.add(map3);for(Map<String,Object> map :list) {System.out.println("List＜T＞ Map:"+map);}System.out.println("---------------------");// 集合Map：Map:Map<String,Object> map = new HashMap<>();List<Map<String,Object>> list2 = new ArrayList<>();Map<String,Object> map4 = new HashMap<>();map4.put("name","小英");map4.put("age",20);Map<String,Object> map5 = new HashMap<>();map5.put("name","小红");map5.put("age",22);Map<String,Object> map6 = new HashMap<>();map6.put("name","小婵");map6.put("age",24);list2.add(map4);list2.add(map5);list2.add(map6);map.put("list1", list);map.put("list2", list2);System.out.println("Map List＜T＞1:"+map);System.out.println("---------------------");Iterator<Map.Entry<String, Object>> it = map.entrySet().iterator();        while(it.hasNext()){            Map.Entry<String, Object> entry = it.next();            System.out.println("Map List＜T＞2:"+"key="+entry.geTKEy()+"  value="+entry.getValue());        }}}

测试输出：

List＜T＞ Map:{name=小婷, age=20}List＜T＞ Map:{name=小霞, age=22}List＜T＞ Map:{name=小桐, age=24}---------------------Map List＜T＞1:{list1=[{name=小婷, age=20}, {name=小霞, age=22}, {name=小桐, age=24}], list2=[{name=小英, age=20}, {name=小红, age=22}, {name=小婵, age=24}]}---------------------Map List＜T＞2:key=list1  value=[{name=小婷, age=20}, {name=小霞, age=22}, {name=小桐, age=24}]Map List＜T＞2:key=list2  value=[{name=小英, age=20}, {name=小红, age=22}, {name=小婵, age=24}]

来源地址：https://blog.csdn.net/qq_42139049/article/details/132567320