lambda中collect去重中的排序坑

记录一个开发过程中遇到的坑：

使用lambda中collect去重时，建议先去重，后排序。

package com.zrh.jsd;

import com.alibaba.fastjson.JSONObject;

import java.util.*;
import java.util.stream.Collectors;

public class TestCollect {
    public static void main(String[] args) {
        BookBo bookBo1 = new BookBo("1", "语文");
        BookBo bookBo2 = new BookBo("2", "数学");
        BookBo bookBo3 = new BookBo("3", "英语");
        BookBo bookBo4 = new BookBo("4", "地理");
        BookBo bookBo5 = new BookBo("5", "生物");
        BookBo bookBo6 = new BookBo("1", "语文");

        List bookBoList = Arrays.asList(bookBo1, bookBo2, bookBo3, bookBo4, bookBo5, bookBo6);
        // 推荐排序方法：先去重，收集，然后排序
        
        // 这样排序会乱：先排序，然后去重
        List distinctList = bookBoList
                .stream().sorted(Comparator.comparing(BookBo::getId))
                .collect(Collectors.collectingAndThen(
                        Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(BookBo::getName))), ArrayList::new
                ));
        System.out.println(JSONObject.toJSON(distinctList));
    }
}

class BookBo {
    String id ;
    String name;

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

    public String getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

错误方法的输出结果：

[{"name":"地理","id":"4"},{"name":"数学","id":"2"},{"name":"生物","id":"5"},{"name":"英语","id":"3"},{"name":"语文","id":"1"}]