List<Map> 获取key重复数据及过滤对应key重复数据
作者:互联网
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;
import java.util.function.Predicate;
public class StreamEx{
//过滤重复数据
public static Predicate distinctByKey (Function keyExtractor){
Map seen = new ConcurrentHashMap<>();
return t->seen.putIfAbsent(keyExtractor.apply(t),Boolean.TRUE)==null;
}
//获取重复数据
public static Predicate getdistinctByKey (Function keyExtractor){
Map seen = new ConcurrentHashMap<>();
return t->seen.putIfAbsent(keyExtractor.apply(t),Boolean.TRUE)!=null;
}
public static void main(String[] args) {
List<Map> list = new ArrayList<Map>();
Map map1 = new HashMap<String,String>();
map1.put("ywxh","123");
map1.put("quantity",10);
map1.put("amount",100);
Map map2 = new HashMap<>();
map2.put("ywxh","223");
map2.put("quantity",15);
map2.put("amount",150);
Map map3 = new HashMap<>();
map3.put("ywxh","123");
map3.put("quantity",5);
map3.put("amount",50);
list.add(map1);
list.add(map2);
list.add(map3);
list.stream().filter(StreamEx.distinctByKey(map->((Map) map).get("ywxh")))
.forEach(
map->{
System.out.println(map.toString());
});
}
}
//可见上述代码打印了去重后的数据信息。
//获取重复的数据只需要StreamEx中的
//returnt->seen.putIfAbsent(keyExtractor.apply(t),Boolean.TRUE)==null;
//改为
//returnt->seen.putIfAbsent(keyExtractor.apply(t),Boolean.TRUE)!=null;
标签:Map,java,重复,util,key,seen,put,import 来源: https://blog.csdn.net/liuerchong/article/details/111872190