Java-List<Map>根据Map里的一个字段的值，去掉重复的Map对象

Question

List<Map>去重复数据

Answer 1

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
* @author Dengyouchao
* @date 2013-9-26下午4:03:27
* @Copyright(c) UCIT
*/
public class RemoveDuplicatesData {

@SuppressWarnings({"rawtypes", "unchecked"})
public static void main(String[] args) {
// TODO Auto-generated method stub
Map<String, Map> msp = new HashMap<String, Map>();
List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
List<Map<String, Object>> listMap = new ArrayList<Map<String,Object>>();
Map<String, Object> map1 = new HashMap<String, Object>();
map1.put("id", "1");
map1.put("name", "p");
Map<String, Object> map2 = new HashMap<String, Object>();
map2.put("id", "3");
map2.put("name", "h");
Map<String, Object> map3 = new HashMap<String, Object>();
map3.put("id", "3");
map3.put("name", "f");
list.add(map1);
list.add(map3);
list.add(map2);

System.out.println("初始数据：" + list.toString());
//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
for(int i = list.size()-1 ; i>=0; i--){
Map map = list.get(i);
String id = (String)map.get("id");
map.remove("id");
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<Map>
Set<String> mspKey = msp.keySet();
for(String key: mspKey){
Map newMap = msp.get(key);
newMap.put("id", key);
listMap.add(newMap);
}

System.out.println("去掉重复数据后的数据：" + listMap.toString());
}

}