一、String去重：

//set集合去重，不改變原有的順序public static void pastLeep1(List<String> list){System.out.println("list = [" + list.toString() + "]");List<String> listNew=new ArrayList<>();Set set=new HashSet();for (String str:list) {if(set.add(str)){listNew.add(str);}}System.out.println("listNew = [" + listNew.toString() + "]");}//遍歷后判斷賦給另一個(gè)list集合public static void pastLeep2(List<String> list){System.out.println("list = [" + list.toString() + "]");List<String> listNew=new ArrayList<>();for (String str:list) {if(!listNew.contains(str)){listNew.add(str);}}System.out.println("listNew = [" + listNew.toString() + "]");}//set去重public static void pastLeep3(List<String> list){System.out.println("list = [" + list + "]");Set set = new HashSet();List<String> listNew=new ArrayList<>();set.addAll(list);listNew.addAll(set);System.out.println("listNew = [" + listNew + "]");}//set去重（縮減為一行）public static void pastLeep4(List<String> list){System.out.println("list = [" + list + "]");List<String> listNew=new ArrayList<>(new HashSet(list));System.out.println("listNew = [" + listNew + "]");}//去重并按自然順序排序public static void pastLeep5(List<String> list){System.out.println("list = [" + list + "]");List<String> listNew=new ArrayList<>(new TreeSet<String>(list));System.out.println("listNew = [" + listNew + "]");}


二、對(duì)象去重方法： package com.hcycom.iams.ncolog;

import java.util.*;
import static java.util.Comparator.comparingLong;
import static java.util.stream.Collectors.collectingAndThen;
import static java.util.stream.Collectors.toCollection;

public class Test {

public static void main(String[] args) {
Data data1 = new Data(1,"aaaa");
Data data2 = new Data(2,"dddd");
Data data3 = new Data(1,"vvvv");
Data data4 = new Data(4,"rrrr");
Data data5 = new Data(1,"ssss");
List<Data> list = Arrays.asList(data1,data2,data3,data4,data5);
List<Data> l = test2(list);
System.out.println(Arrays.toString(l.toArray()));

}

//對(duì)象去重
public static List<Data> test2(List<Data> list){
List<Data> unique = list.stream().collect(
collectingAndThen(
toCollection(() -> new TreeSet<>(comparingLong(Data::getId))), ArrayList::new)
);
return unique;
}
}

// 實(shí)體對(duì)象
class Data{

private int id;
private String name;

public Data(int id, String name) {
this.id = id;
this.name = name;
}

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

@Override
public String toString() {
return "Data{" +
"id=" + id +
", name='" + name + '\'' +
'}';
}
}

轉(zhuǎn)載于:https://www.cnblogs.com/typ1805/p/8068289.html

總結(jié)

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