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:ListList<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