从上面的两个接口看Collections.sort()与Arrays.sort()的两种用法是这篇文章的主要目的。
Collections.sort()是集合的排序，在使用此方法的时候有两种途径可供我们选择：一种是要排序的集合中的成员实现Comparable接口，并重写conpareTo()；另一种是实现自己的排序类（实现Comparator），并作为参数传给sort()方法。示意如下：
方法1： class Student implenents Comparable{compareTo()}//要排序的类
ArrayList list = new ArrayList().add(new Student());//将上诉类装到集合中
Collection.sort(list);//调用Collection的sort()方法进行排序
方法2： class Student{}//要排序的类
MyComparator implenents Comparator{compare()}//实现自己的排序类
ArrayList list = new ArrayList().add(new Student());//将上诉类装到集合中
Collection.sort(list,new MyComparator());//调用Collection的sort()方法进行排序，并将自己的排序类作为参数传递
Arrays.sort()是对数组尽心排序，排序的途径与Collection类似。一种是要排序的集合中的成员实现Comparable接口，并重写conpareTo()；另一种是实现自己的排序类（实现Comparator），并作为参数传给sort()方法。示意如下：
方法1： class Student implenents Comparable{compareTo()}//要排序的类
Student[] student = {new Student()}//此时不是装到集合中，而是装到数组中
Arrays.sort(list);//调用Arrays的sort()方法进行排序
方法2： class Student{}//要排序的类
MyComparator implenents Comparator{compare()}//实现自己的排序类
Student[] student = {new Student()}//此时不是装到集合中，而是装到数组中
Arrays.sort(list,new MyComparator());//调用Arrays的sort()方法进行排序，并将自己的排序类作为参数传递
从上面的抽象出的过程可以看出，Collections与Arrays的排序过程是一样的，只不过是将Collection换做Arrays而已。
下面给出类的目录结构图：
，上面的Comparable是测试Comparable按案例，下面的Comparator是测试Comparator的案例，两种案例中分别给出了集合和数组的排序。下面给出具体的测试代码，按照上图中的从上到下的类顺序：
1 package Comparable;
2
3 import java.util.Arrays;
4
5 import org.junit.Test;
6
7 public class ArraysTest {
8 @Test
9 public void test(){
10 Student stu1 = new Student("alsa", 21);
11 Student stu3 = new Student("foas", 17);
12 Student stu4 = new Student("mike", 25);
13 Student stu6 = new Student("zieka", 17);
14 Student stu2 = new Student("dava", 24);
15 Student stu5 = new Student("nose", 14);
16
17 Student[] student = {stu1,stu2,stu3,stu4,stu5,stu6};
18
19 System.out.println("排序前");
20 for(int i = 0;i<student.length;i++){
21 System.out.println(student[i]);
22 }
23
24 Arrays.sort(student);
25
26 System.out.println("排序后");
27 for(int i = 0;i<student.length;i++){
28 System.out.println(student[i]);
29 }
30 }
31 }
1 package Comparable;
2
3 import java.util.ArrayList;
4 import java.util.Collections;
5
6 import org.junit.Test;
7
8
9
10 public class CollectionTest {
11 @Test
12 public void test(){
13 //这里都用英文名字是为了看字符串的排序
14 Student stu1 = new Student("alsa", 21);
15 Student stu3 = new Student("foas", 17);
16 Student stu4 = new Student("mike", 25);
17 Student stu6 = new Student("zieka", 17);
18 Student stu2 = new Student("dava", 24);
19 Student stu5 = new Student("nose", 14);
20
21 ArrayList<Student> list = new ArrayList<Student>();
22 list.add(stu1);
23 list.add(stu2);
24 list.add(stu3);
25 list.add(stu4);
26 list.add(stu5);
27 list.add(stu6);
28 System.out.println("排序前");
29 for(Student l:list){
30 System.out.println(l);
31 }
32 System.out.println("排序后");
33 Collections.sort(list);
34 for(Student l:list){
35 System.out.println(l);
36 }
37 }
38
39
40 }
1 package Comparable;
2
3 class Student implements Comparable<Object>{
4 String name;
5 int age;
6
7 public Student(String name, int age) {
8 super();
9 this.name = name;
10 this.age = age;
11 }
12
13 public String getName() {
14 return name;
15 }
16
17 public void setName(String name) {
18 this.name = name;
19 }
20
21 public int getAge() {
22 return age;
23 }
24
25 public void setAge(int age) {
26 this.age = age;
27 }
28
29 @Override
30 public String toString() {
31 return "Student [name=" + name + ", age=" + age + "]";
32 }
33
34 @Override
35 public int compareTo(Object o) {
36 // TODO Auto-generated method stub
37 if(((Student)o).age>age){
38 return 1;
39 }else if(((Student)o).age<age){
40 return -1;
41 }else{
42 return ((Student)o).name.compareTo(name);
43 }
44
45 }
46
47 }
1 package ComparatorTest;
2
3 import java.util.Arrays;
4 import java.util.Comparator;
5
6 import org.junit.Test;
7
8 class MyComparator1 implements Comparator<Object>{
9
10 @Override
11 public int compare(Object o1, Object o2) {
12 // TODO Auto-generated method stub
13 if(((Student)o1).age>((Student)o2).age){
14 return 1;
15 }else if(((Student)o1).age<((Student)o2).age){
16 return -1;
17 }else{
18 return ((Student)o1).name.compareTo(((Student)o2).name);
19 }
20 }
21
22 }
23
24 public class ArraysTest {
25 @SuppressWarnings("unchecked")
26 @Test
27 public void test(){
28 Student stu1 = new Student("alsa", 21);
29 Student stu3 = new Student("foas", 17);
30 Student stu4 = new Student("mike", 25);
31 Student stu6 = new Student("zieka", 17);
32 Student stu2 = new Student("dava", 24);
33 Student stu5 = new Student("nose", 14);
34
35 Student[] student = {stu1,stu2,stu3,stu4,stu5,stu6};
36 System.out.println("排序前");
37 for(int i = 0;i<student.length;i++){
38 System.out.println(student[i]);
39 }
40 Arrays.sort(student,new MyComparator1());
41 System.out.println("排序后");
42 for(int i = 0;i<student.length;i++){
43 System.out.println(student[i]);
44 }
45 }
46 }
1 package ComparatorTest;
2
3
4 import java.util.ArrayList;
5 import java.util.Collections;
6 import java.util.Comparator;
7
8 import org.junit.Test;
9
10 @SuppressWarnings("rawtypes")
11 class MyComparator implements Comparator{
12
13 @Override
14 public int compare(Object o1, Object o2) {
15 // TODO Auto-generated method stub
16 if(((Student)o1).age>((Student)o2).age){
17 return 1;
18 }else if(((Student)o1).age<((Student)o2).age){
19 return -1;
20 }else{
21 return ((Student)o1).name.compareTo(((Student)o2).name);
22 }
23 }
24
25 }
26
27 public class CollectionTest {
28 @SuppressWarnings("unchecked")
29 @Test
30 public void test(){
31 //这里都用英文名字是为了看字符串的排序
32 Student stu1 = new Student("alsa", 21);
33 Student stu3 = new Student("foas", 17);
34 Student stu4 = new Student("mike", 25);
35 Student stu6 = new Student("zieka", 17);
36 Student stu2 = new Student("dava", 24);
37 Student stu5 = new Student("nose", 14);
38
39 ArrayList<Student> list = new ArrayList<Student>();
40 list.add(stu1);
41 list.add(stu2);
42 list.add(stu3);
43 list.add(stu4);
44 list.add(stu5);
45 list.add(stu6);
46 System.out.println("排序前");
47 for(Student l:list){
48 System.out.println(l);
49 }
50 System.out.println("排序后");
51 Collections.sort(list, new MyComparator());
52 for(Student l:list){
53 System.out.println(l);
54 }
55 }
56
57
58 }
1 package ComparatorTest;
2
3 public class Student {
4 String name;
5 int age;
6
7 public Student(String name, int age) {
8 super();
9 this.name = name;
10 this.age = age;
11 }
12
13 public String getName() {
14 return name;
15 }
16
17 public void setName(String name) {
18 this.name = name;
19 }
20
21 public int getAge() {
22 return age;
23 }
24
25 public void setAge(int age) {
26 this.age = age;
27 }
28
29 @Override
30 public String toString() {
31 return "Student [name=" + name + ", age=" + age + "]";
32 }
33
34 }
来源：https://www.cnblogs.com/Jc-zhu/p/4466133.html