Java8根据List对象中的属性进行分组

Java8根据List对象中的属性进行分组

代码演示

List students = new ArrayList<>();
        Student student1 = new Student();
        student1.setAge(18);
        student1.setName("赵");
        student1.setSex("男");
        Student student2 = new Student();
        student2.setAge(19);
        student2.setName("钱");
        student2.setSex("女");
        Student student3 = new Student();
        student3.setAge(20);
        student3.setName("孙");
        student3.setSex("女");
        Collections.addAll(students,student1,student2,student3);
        //根据学生性别分组
        Map> map = students.stream().collect(Collectors.groupingBy(Student::getSex));
        for (Map.Entry> m:map.entrySet()) {
            System.out.println("key="+m.getKey());
            System.out.println("value="+m.getValue());
        }

执行结果

 根据key获取数据

//根据学生性别分组
        Map> map = students.stream().collect(Collectors.groupingBy(Student::getSex));
        //获取所有的女生
        System.out.println(map.get("女"));

 执行结果