优雅的使用.toMap转换为Map集合

import com.alibaba.fastjson.JSON;
import com.example.demo.Demo.dto.Student;

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

public class Test02 {
    public static void main(String[] args) {

        Map<Integer, Student> studentMap;

        Student student01 = new Student(1, "张三", String.valueOf(new Date()));
        Student student02 = new Student(2, "李四", String.valueOf(new Date()));
        Student student03 = new Student(3, "王五", String.valueOf(new Date()));


        List<Student> arrayList = new ArrayList<>();
        Collections.addAll(arrayList, student01, student02, student03);

        studentMap = arrayList.stream().collect(Collectors.toMap(Student::getId, Function.identity(), (key1, key2) -> key2));


        studentMap.forEach((key, value) -> System.out.println("key: " + key + ", value: " + JSON.toJSON(value)));
		// TODO: key: 1, value: {"date":"Wed Jun 30 15:17:37 CST 2021","name":"张三","id":1}
		// TODO: key: 2, value: {"date":"Wed Jun 30 15:17:37 CST 2021","name":"李四","id":2}
		// TODO: key: 3, value: {"date":"Wed Jun 30 15:17:37 CST 2021","name":"王五","id":3}

        System.out.println("----------------------------------------------------------------------------------");

        System.out.println(JSON.toJSON(studentMap.get(2)));
		// TODO: {"date":"Wed Jun 30 15:18:38 CST 2021","name":"李四","id":2}
    }
}

优雅的使用.toMap转换为Map集合

原文：https://www.cnblogs.com/Twittery/p/14954709.html