list集合根據某字段進行排序

1、Collections.sort()

//升序排列
Collections.sort(list, new Comparator<Student>() {
    public int compare(Student s1, Student s2) {
        return s1.getAge().compareTo(s2.getAge());
    }
});

//降序排列
Collections.sort(list, new Comparator<Student>() {
    public int compare(Student s1, Student s2) {
        return s2.getAge().compareTo(s1.getAge());
    }
});

//多條件-先年齡升序、后分數升序
Collections.sort(list, new Comparator<Student>() {
    public int compare(Student s1, Student s2) {
        int i = s1.getAge().compareTo(s2.getAge());
        if(i == 0) {
            i = s1.getScore().compareTo(s2.getScore());
        }
        return i;
    }
});

//如日期集合List<Date> list = new ArrayList<>();
Collections.sort(list, new Comparator<Date>() {
    public int compare(Date s1, Date s2) {
        return s1.compareTo(s2);
    }
});

java8可使用
2、list.sort()

//升序排列
list.sort((x,y)->Integer.compare(x.getAge(), y.getAge()));
list.sort((x,y)->x.getAge().compareTo(y.getAge())); //降序排列
list.sort((x,y)->Integer.compare(y.getAge(), x.getAge()));
//如日期集合List<Date> list = new ArrayList<>();
list.sort((x,y)->x.compareTo(y));

3、list.stream()

//升序排列
list = list.stream().sorted(Comparator.comparing(Student::getAge)).collect(Collectors.toList());
list = list.stream().sorted(Comparator.comparingInt(Student::getAge)).collect(Collectors.toList());
//使用lambda表達式
list = list.stream().sorted(Comparator.comparing(e -> e.getAge())).collect(Collectors.toList());
//降序排列
list = list.stream().sorted(Comparator.comparing(Student::getAge).reversed()).collect(Collectors.toList());
//多條件-先年齡升序、后分數升序
list = list.stream().sorted(Comparator.comparing(Student::getAge).thenComparing(Comparator.comparing(Student::getScore))).collect(Collectors.toList());