在steam流中给list元素设置序号

参考资料地址1: 数组方式

参考资料地址2: AtomicInteger方式

测试代码

    /**
     * lambda 表达式中设置序号
     */
    @Test
    public void test6() {
        //基础数据准备
        List<NumStudent> list = Arrays.asList(new NumStudent(null, "张三", 18), new NumStudent(null, "李四", 19), new NumStudent(null, "李无", 20));
        //需求根据年龄大小排序并设置序号
        //1 利用数组
        //int[] index={1};
        //list.stream().sorted(Comparator.comparing(NumStudent::getAge)).forEach(s -> s.setNum(index[0]++));
        //2 利用AtomicInteger
        AtomicInteger index = new AtomicInteger();
        list.stream().sorted(Comparator.comparing(NumStudent::getAge)).forEach(s->s.setNum(index.incrementAndGet()));
        System.out.println(list);
        //[StreamTest.NumStudent(num=1, name=张三, age=18), StreamTest.NumStudent(num=2, name=李四, age=19), StreamTest.NumStudent(num=3, name=李无, age=20)]
    }

steam流.peek(中间操作) 使用示例

    /**
     * peek(中间操作) 使用示例
     */
    @Test
    public void test7() {
        List<Student> list = Arrays.asList(new Student("张三", 18), new Student("李四", 19));
        //年龄脱敏 并做一些其他处理(略)
        List<Student> resultList = list.stream().peek(s -> s.setAge(null)).collect(Collectors.toList());
        System.out.println(resultList);
        //[StreamTest.Student(name=张三, age=null), StreamTest.Student(name=李四, age=null)]
    }