Java中list<Object[]>、list<Student>、list<Map<String,String>>排序

1：list<Object[]>的排序

 

 public static void main(String[] args) {

// TODO Auto-generated method stub

        Object[] o1 = new Object[4];

        o1[0] = "5";

        o1[1] = "o1";

        o1[2] = "o11";

        o1[3] = "o111";

        Object[] o2 = new Object[4];

        o2[0] = "3";

        o2[1] = "o2";

        o2[2] = "o22";

        o2[3] = "o222";

        List<Object[]> list = new ArrayList<>();

        list.add(o1);

        list.add(o2);


//很明显我们先添加的对象o1，所以先打印o1，

        for (inti = 0; i < list.size(); i++) {

            for (intj = 0; j < 4; j++) {

                System.out.print(list.get(i)[j] + "  ");

            }

        }


        System.out.println("
排序后-------");

        sortList(list);


//排序后：

        for (inti = 0; i < list.size(); i++) {

            for (intj = 0; j < 4; j++) {

                System.out.print(list.get(i)[j] + "  ");

            }

        }
    }

 

写一个方法

 

public staticvoid sortList(List<Object[]> ls) {

        Collections.sort(ls, new Comparator<Object[]>() {

            @Override

            public int compare(Object[] o1, Object[] o2) {

                if (Integer.valueOf(o1[0].toString()) > Integer.valueOf(o2[0].toString())) {

                    return 1;

                }


                return -1;

            }

        });

    }

 

 

 

2：list<Student>排序，主要是正对汉族的排序，按照拼音排序.

首先写一个Student类

    package com.model;


    public class Student {

        public Stringname;

        publicintage;

        public Student(Stringname, intage) {

            this.name = name;

            this.age = age;

        }

        public void setName(String name) {

            this.name = name;

        }

        public String getName() {

            returnname;

        }


        public void setAge(int age) {

            this.age = age;

        }

        public int getAge() {

            returnage;

        }

    }

然后在main方法中调用，（这里写的是一个java文件）

 Student stu1 = new Student("张三", 23);

        Student stu2 = new Student("李四", 25);

        List<Student> listStudent = new ArrayList<>();

        listStudent.add(stu1);

        listStudent.add(stu2);


        System.out.println();

        for (int i = 0; i < listStudent.size(); i++) {

            System.out.print(listStudent.get(i).getName() + "---" + listStudent.get(i).getAge());


        }

        System.out.println("
排序后");

        sortListStudent(listStudent);

        for (int i = 0; i < listStudent.size(); i++) {

            System.out.print(listStudent.get(i).getName() + "---" + listStudent.get(i).getAge());


        }

写一个排序方法

 public staticvoid sortListStudent(List<Student> ls) {

        Collections.sort(ls, new Comparator<Student>() {


            @Override

            public int compare(Student o1, Student o2) {

                String s1 = o1.getName();

                String s2 = o2.getName();

                if (s1.compareTo(s2) > 0) {

                    return -1;

                }

                return 1;

            }


        });


    }

结果图：

 

3：list<Map<String,String>>排序问题：

public class MapListSort {
        public static void main(String[] args) {
            // TODO Auto-generated method stub
            List<Map<String, String>> listMap = new ArrayList<>();
            Map<String, String> map1 = new HashMap<String, String>();
            map1.put("map001", "001");
            map1.put("map003", "map003");
            map1.put("map002", "map002");
            Map<String, String> map2 = new HashMap<String, String>();
            map2.put("map001", "101");
            map2.put("map003", "map303");
            map2.put("map002", "map202");
            //先添加的map2，但是map2中map001的值大于map1中的map001的值。
            listMap.add(map2);
            listMap.add(map1);

            for (int i = 0; i < listMap.size(); i++) {
                System.out.print(listMap.get(i).get("map001") + "," + listMap.get(i).get("map002") + "," + listMap.get(i).get("map003") + "
");
            }

            mapSorts(listMap);

            System.out.println("
排序后：");
            for (int i = 0; i < listMap.size(); i++) {
                System.out.print(listMap.get(i).get("map001") + "," + listMap.get(i).get("map002") + "," + listMap.get(i).get("map003") + "
");
            }
        }

        public static void mapSorts(List<Map<String, String>> map) {
            Collections.sort(map, new Comparator<Map<String, String>>() {

                @Override
                public int compare(Map<String, String> o1, Map<String, String> o2) {
                    // TODO Auto-generated method stub
                    if (o1.get("map001").compareTo(o2.get("map001")) > 0) {
                        return 1;
                    }
                    return -1;
                }
            });
        }
    }