1.定义自己的 MyComparable 接口
1 package Test.treeSetDemo;
2
3 public interface MyComparable <E>{
4 int compareTo(E e);
5 }
2.定义自己的 MyComparator接口
1 package Test.treeSetDemo;
2
3 public interface MyComparator {
4 int compare(Student student1,Student student2);
5 }
3.定义自己的排序类
1 package Test.treeSetDemo;
2
3 import java.util.ArrayList;
4 import java.util.Comparator;
5
6 public class MyArray {
7 private ArrayList <Student> students = new ArrayList<>();
8 /*
9 1.直接排序 实现对象的排序
10 缺点:1.只能根据年龄排序
11 2.只能排一种顺序 无法先年龄后身高
12 */
13 public void sort(){
14 //使用冒泡排序比较年龄 排ArrayList中的对象
15 for (int i = 0; i < students.size(); i++) {
16 for (int j = 0; j < students.size()-1; j++) {
17 Student current = students.get(j);
18 Student next = students.get(j + 1);
19 if (current.getAge()>next.getAge()){
20 Student temp = current;
21 students.set(j,next);
22 students.set(j+1,temp);
23 }
24 }
25 }
26 }
27
28 /*
29 2.让对象可比 即对象实现comparable
30 */
31 public void sort2(){
32 //使用冒泡排序比较年龄 排ArrayList中的对象
33 for (int i = 0; i < students.size(); i++) {
34 for (int j = 0; j < students.size()-1; j++) {
35 Student current = students.get(j);
36 Student next = students.get(j + 1);
37 if (current.compareTo(next)>0){
38 Student temp = current;
39 students.set(j,next);
40 students.set(j+1,temp);
41 }
42 }
43 }
44 }
45 /*
46 3.传入一个比较器对象
47 */
48 public void sort2(MyComparator comparator){
49 //使用冒泡排序比较年龄 排ArrayList中的对象
50 for (int i = 0; i < students.size(); i++) {
51 for (int j = 0; j < students.size()-1; j++) {
52 Student current = students.get(j);
53 Student next = students.get(j + 1);
54 int result=comparator.compare(current,next);
55 //要实现排序 if 这儿的boolean结果是个关键 而求boolean的这个过程不一定非要在自己类中实现
56 if (result>0){
57 Student temp = current;
58 students.set(j,next);
59 students.set(j+1,temp);
60 }
61 }
62 }
63 }
64
65 public ArrayList<Student> getStudents() {
66 return students;
67 }
68 public void setStudents(ArrayList<Student> students) {
69 this.students = students;
70 }
71 }
4.定义对象的类
1 package Test.treeSetDemo;
2
3 class Student implements MyComparable<Student>{
4 private String name;
5 private int age;
6 private int height;
7
8 public String getName() {
9 return name;
10 }
11
12 public void setName(String name) {
13 this.name = name;
14 }
15
16 public int getAge() {
17 return age;
18 }
19
20 public void setAge(int age) {
21 this.age = age;
22 }
23
24 public Student() {
25 }
26
27 public Student(String name, int age) {
28 this.name = name;
29 this.age = age;
30 }
31
32 @Override
33 public int compareTo(Student o) {
34 int result=this.age -o .age;
35 return result;
36 }
37
38 @Override
39 public String toString() {
40 return "Student{" +
41 "name='" + name + '\'' +
42 ", age=" + age +
43 ", height=" + height +
44 '}';
45 }
46
47 public Student(String name, int age, int height) {
48 this.name = name;
49 this.age = age;
50 this.height = height;
51 }
52
53 public int getHeight() {
54 return height;
55 }
56
57 public void setHeight(int height) {
58 this.height = height;
59 }
60 }
5.测试
1 package Test.treeSetDemo;
2
3 import java.util.ArrayList;
4
5 public class Test {
6 public static void main(String[] args) {
7 MyArray myArray = new MyArray();
8 ArrayList<Student> students = myArray.getStudents();
9 students.add(new Student("aaa", 111,175));
10 students.add(new Student("bbb", 102,180));
11 students.add(new Student("ccc", 195,182));
12 students.add(new Student("ddd", 333,179));
13 students.add(new Student("eee", 111,180));
14 // 1.直接排序 实现对象的排序
15 myArray.sort();
16 for (Student student : students) {
17 System.out.println(student);
18 }
19 System.out.println("------------------------------------");
20 // 2.让对象可比 即对象实现comparable
21 myArray.sort2();
22 for (Student student : students) {
23 System.out.println(student);
24 }
25 System.out.println("------------------------------------");
26 //3.传入一个比较器对象
27 myArray.sort2(new MyComparator() {
28 @Override
29 public int compare(Student student1, Student student2) {
30 int result=student1.getHeight()-student2.getHeight();//先比身高 升序
31 result= result==0?student2.getAge()-student1.getAge():result;//后比年龄 降序
32 return result;
33 }
34 });
35 for (Student student : students) {
36 System.out.println(student);
37 }
38 }
39 }
