Stream流排序数组和List 详解

目录

• 一、对象单字段排序
• 二、多字段排序
• 三、数组排序以及List<Integer>排序

一、对象单字段排序

        List<People> peopleList = Lists.newArrayList();
        peopleList.add(new People(1, "小王", 5));
        peopleList.add(new People(1, "小李", 4));
        peopleList.add(new People(2, "小张", 3));
        peopleList.add(new People(2, "小皇", 2));
        peopleList.add(new People(2, "小刘", 1));

        //单字段排序
        peopleList =  peopleList.stream().sorted(Comparator.comparing(People::getJgId)).collect(Collectors.toList());
        log.info(peopleList.toString());
        //这里是根据userId 进行排序——降序排序  reversed()
        peopleList =  peopleList.stream().sorted(Comparator.comparing(People::getJgId).reversed()).collect(Collectors.toList());
        log.info(peopleList.toString());

二、多字段排序

        List<People> peopleList = Lists.newArrayList();
        peopleList.add(new People(1, "小王", 5));
        peopleList.add(new People(1, "小李", 4));
        peopleList.add(new People(2, "小张", 3));
        peopleList.add(new People(2, "小皇", 2));
        peopleList.add(new People(2, "小刘", 1));
        //这里是根据Id及jgId进行联合升序排序
        peopleList =  peopleList.stream().sorted(Comparator.comparing(People::getId).thenComparing(People::getJgId)).collect(Collectors.toList());
        log.info(peopleList.toString());
        //下面两个结果都是以Id降序jgId升序排序的结果，但是查询方式不同
        //先以id升序,升序结果进行id降序,再进行jgId升序
        peopleList =  peopleList.stream().sorted(Comparator.comparing(People::getId).reversed().thenComparing(People::getJgId)).collect(Collectors.toList());
        log.info(peopleList.toString());
        //先以id降序,再进行jgId升序 **推荐使用该种方式**
        peopleList =  peopleList.stream().sorted(Comparator.comparing(People::getId,Comparator.reverseOrder()).thenComparing(People::getJgId)).collect(Collectors.toList());
        log.info(peopleList.toString());
        //先以id升序,再进行jgId降序
        peopleList =  peopleList.stream().sorted(Comparator.comparing(People::getId).thenComparing(People::getJgId,Comparator.reverseOrder())).collect(Collectors.toList());
        log.info(peopleList.toString());

三、数组排序以及List<Integer>排序

先把数组转换成List对象再进行排序