lamdba總結

1. lamdba中使用method refenrence對list集合進行排序

1. 基礎數據類型排序

//初始化集合
List<Integer> list = Lists.list(1, 2, 3, 4);
//升序排序
Comparator.sort(list,new Comparator<Integer>(){
    @Override
    public int compare(Integer o1,Integer o2){
        return o1.compareTo(o2); //降序同理
    }
});

list.forEach(System.out::println)

//優化之後
Collections.sort(list, (o1, o2) -> o1.compareTo(o2));

//升序優化最後的效果
Collections.sort(list, Integer::compareTo);

//降序優化最後的效果
Collections.sort(list, Comparator.reverseOrder());

2. 對象排序

//初始化集合對象數據
List<Status> studentList = Lists.list(new Student("張三","男","10"),new Student("李四","女","20"),new Student("王五","男","30"));

//升序排序
Collections.sort(studentList,new Comparator<Student>(){
    @Override
    public int compare(Student o1,Student o2){
        return o1.getSage().compareTo(o2.getSage());//降序同理
    }
});

//升序排序優化後
Collections.sort(studentList,(Comparator.comparing(Student::getSage)));

//降序排序優化後
collections.sort(studentList,(o1.getSage(),o2.getSage()) -> o2.getSage().comparing(o1.getSage()))