Java : List中 根据map的某个key去重

话不多说，看代码和效果

/**

* 根据map中的某个key 去除List中重复的map

* @author shijing

* @param list

* @param mapKey

* @return

*/

public static List> removeRepeatMapByKey(List>

list, String mapKey){

if (CollectionUtils.isNullOrEmpty(list)) return null;

//把list中的数据转换成msp,去掉同一id值多余数据，保留查找到第一个id值对应的数据

List> listMap = new ArrayList<>();

Map msp = new HashMap<>();

for(int i = list.size()-1 ; i>=0; i--){

Map map = list.get(i);

String id = (String)map.get(mapKey);

map.remove(mapKey);

msp.put(id, map);

}

//把msp再转换成list,就会得到根据某一字段去掉重复的数据的List

Set mspKey = msp.keySet();

for(String key: mspKey){

Map newMap = msp.get(key);

newMap.put(mapKey, key);

listMap.add(newMap);

}

return listMap;

}

测试：

public static void main(String[] args) {

Map msp = new HashMap();

List> list = new ArrayList>();

List> listMap = new ArrayList>();

Map map1 = new HashMap();

map1.put("id", "1123");

map1.put("name", "张三");

Map map2 = new HashMap();

map2.put("id", "2");

map2.put("name", "李四");

Map map3 = new HashMap();

map3.put("id", "1123");

map3.put("name", "王五");

Map map4 = new HashMap();

map4.put("id", "3");

map4.put("name", "赵六");

list.add(map1);

list.add(map2);

list.add(map3);

list.add(map4);

System.out.println("初始数据：" + list.toString());

System.out.println("去重之后：" + removeRepeatMapByKey(list,"id"));

}

结果：

初始数据：[{name=张三, id=1123}, {name=李四, id=2}, {name=王五, id=1123}, {name=赵六, id=3}]

去重之后：[{name=李四, id=2}, {name=赵六, id=3}, {name=张三, id=1123}]