Java中list集合stream流去重

1. List单个字段去重

list.stream().distinct().collect(Collectors.toList());

2. List对象集合根据一个或者多个字段去重

准备类：

@Datapublic class Book {    private Long id;    private String name;    private Double price;}

（1）根据单字段name去重

bookList.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(Book::getName))), ArrayList::new));

（2）根据多字段name price去重

bookList.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(book -> book.getName() + "-" + book.getPrice()))), ArrayList::new));

（3）示例

import java.util.ArrayList;import java.util.Comparator;import java.util.List;import java.util.TreeSet;import java.util.stream.Collectors;import lombok.Data; @Datapublic class Book {    private Long id;    private String name;    private Double price;     public Book(Long id, String name, Double price) {        this.id = id;        this.name = name;        this.price = price;    }     public static void main(String[] args) {        List<Book> bookList = new ArrayList<>();        bookList.add(new Book(1L, "书本1", 1.1));        bookList.add(new Book(2L, "书本1", 1.1));        bookList.add(new Book(3L, "书本2", 2.2));        bookList.add(new Book(4L, "书本2", 4.4));        // 根据单字段name去重        List<Book> bookList1 = bookList.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(Book::getName))), ArrayList::new));        System.out.println("单字段去重结果：" + bookList1.toString());        // 根据多字段name price去重        List<Book> bookList2 = bookList.stream().collect(Collectors.collectingAndThen(Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(book -> book.getName() + "-" + book.getPrice()))), ArrayList::new));        System.out.println("多字段去重结果：" + bookList2.toString());    }}

输出打印结果

单字段去重结果：[Book(id=1, name=书本1, price=1.1), Book(id=3, name=书本2, price=2.2)]多字段去重结果：[Book(id=1, name=书本1, price=1.1), Book(id=3, name=书本2, price=2.2), Book(id=4, name=书本2, price=4.4)]

来源地址：https://blog.csdn.net/qq_42546307/article/details/130520716