集合排序

整形数据排序

    /**
     * 列表排序
     */
    private static void sortList() {
        List<Integer> list = new ArrayList<Integer>();
        list.add(4);
        list.add(2);
        list.add(6);
        System.out.println("begin list" + list.toString());
        Collections.sort(list);
        System.out.println("end list" + list.toString());
    }

 

列表对象排序

        //排序按照年龄升序
        stuList.sort(Comparator.comparing(stu -> stu.getAge()));
        stuList = stuList.stream().sorted(Comparator.comparing(obj -> obj.getAge())).collect(Collectors.toList());
        stuList = stuList.stream().sorted(Comparator.comparing(StudentInfo::getAge)).collect(Collectors.toList());
        System.out.println("排序按照年龄升序： " + stuList.toString());


        //排序按照年龄降序
        stuList.sort(Comparator.comparing(stu -> ((StudentInfo) stu).getAge()).reversed());
        System.out.println("排序按照年龄降序： " + stuList.toString());

 

获取年龄小于25岁人的List集合

        //获取年龄小于25岁人的List集合
        List<StudentInfo> lessAgeList = stuList.stream().filter(stu -> stu.getAge() < 25).collect(Collectors.toList());
        System.out.println("lessAgeList: " + lessAgeList.toString());

 

循环遍历每个元素

        //循环遍历每个元素
        System.out.println("循环遍历每个元素: ");
        stuList.stream().forEach(stu -> {
            System.out.print("stu.getAge(): " + stu.getAge());
            System.out.println("stu.getName(): " + stu.getName());
        });