Java中的数组排序

Java中的数组排序，一般是利用Arrays.sort(),这个方法是经过优化的快速排序。在Arrays种有多中形式的重载，在这里就不一一列举了。

数组排序的种类：

1.非降序排序，非升序排序（就排序后数组元素排列的结果而言）

2.基本类型数据的排序，类类型数据的排序（就排序的对象而言）

排序示例：

int型数组的非降序排序：

 1 package sort;
 2 
 3 import java.util.Arrays;
 4 
 5 public class Main {
 6     public static void displayArray(int[] array) {
 7         for (int i: array) {
 8             System.out.print(i + " ");
 9         }
10         System.out.println();
11     }
12     
13     public static void main(String[] args) {
14         int[] arr = new int[]{43, 84, 3, 8, 4, 7, 3, 75, 82, 748, 35};
15         
16         System.out.println("排序前:");
17         displayArray(arr);
18         
19         Arrays.sort(arr);
20         
21         System.out.println("排序后:");
22         displayArray(arr);
23     }
24 }

View Code

运行结果如下:

int型数组的非升序排序：

 1 package sort;
 2 
 3 import java.util.Arrays;
 4 import java.util.Comparator;
 5 
 6 public class Main {
 7     public static void displayArray(Integer[] array) {
 8         for (int i: array) {
 9             System.out.print(i + " ");
10         }
11         System.out.println();
12     }
13     
14     public static void main(String[] args) {
15         Integer[] arr = new Integer[]{43, 84, 3, 8, 4, 7, 3, 75, 82, 748, 35};
16         
17         System.out.println("排序前:");
18         displayArray(arr);
19         
20         Arrays.sort(arr, new JX());
21         
22         System.out.println("排序后:");
23         displayArray(arr);
24     }
25 }
26 
27 class JX implements Comparator<Integer> {
28     @Override
29     public int compare(Integer o1, Integer o2) {
30         if (o1 <= o2) {
31             return 1;
32         }
33         return -1;
34     }
35 }

View Code

运行结果如下：

类类型的非降序排序：

 1 package sort;
 2 
 3 import java.util.Arrays;
 4 
 5 public class Main {
 6     public static void displayArray(Student[] student) {
 7         for (Student s : student) {
 8             System.out.println(s);
 9         }
10     }
11     
12     public static void main(String[] args) {
13         Student[] s = new Student[5];
14         s[0] = new Student("wwww", 20, 2.34);
15         s[1] = new Student("kkkk", 2, 2.34);
16         s[2] = new Student("pppp", 25, 3.34);
17         s[3] = new Student("hhhh", 12, 4.34);
18         s[4] = new Student("jjjj", 10, 5.34);
19         
20         System.out.println("排序前:");
21         displayArray(s);
22         
23         Arrays.sort(s);
24         
25         System.out.println("排序后:");
26         displayArray(s);
27     }
28 }
29 
30 /*
31  * 根据年龄进行非降序排序
32  */
33 class Student implements Comparable<Student> {
34     private String name;
35     private int age;
36     private double height;
37     
38     public Student(String name, int age, double height) {
39         this.name = name;
40         this.age = age;
41         this.height = height;
42     }
43     
44     @Override
45     public int compareTo(Student o) {
46         if (this.age <= o.age) {
47             return -1;
48         }
49         return 1;
50     }
51     
52     public String toString() {
53         return "Name: " + name + " Age: " + age + " Height: " + height;
54     }
55 }

View Code

运行结果如下：

类类型的非升序排序：

 1 package sort;
 2 
 3 import java.util.Arrays;
 4 
 5 public class Main {
 6     public static void displayArray(Student[] student) {
 7         for (Student s : student) {
 8             System.out.println(s);
 9         }
10     }
11     
12     public static void main(String[] args) {
13         Student[] s = new Student[5];
14         s[0] = new Student("wwww", 20, 2.34);
15         s[1] = new Student("kkkk", 2, 2.34);
16         s[2] = new Student("pppp", 25, 3.34);
17         s[3] = new Student("hhhh", 12, 4.34);
18         s[4] = new Student("jjjj", 10, 5.34);
19         
20         System.out.println("排序前:");
21         displayArray(s);
22         
23         Arrays.sort(s);
24         
25         System.out.println("排序后:");
26         displayArray(s);
27     }
28 }
29 
30 /*
31  * 根据年龄进行非升序排序
32  */
33 class Student implements Comparable<Student> {
34     private String name;
35     private int age;
36     private double height;
37     
38     public Student(String name, int age, double height) {
39         this.name = name;
40         this.age = age;
41         this.height = height;
42     }
43     
44     @Override
45     public int compareTo(Student o) {
46         if (this.age <= o.age) {
47             return 1;
48         }
49         return -1;
50     }
51     
52     public String toString() {
53         return "Name: " + name + " Age: " + age + " Height: " + height;
54     }
55 }

View Code

运行结果如下:

根据指定属性对类类型数组排序：

 1 package sort;
 2 
 3 import java.util.Arrays;
 4 import java.util.Comparator;
 5 
 6 public class Main {
 7     public static void displayArray(Student[] student) {
 8         for (Student s : student) {
 9             System.out.println(s);
10         }
11     }
12     
13     public static void main(String[] args) {
14         Student[] s = new Student[5];
15         s[0] = new Student("wwww", 20, 2.34);
16         s[1] = new Student("kkkk", 2, 2.34);
17         s[2] = new Student("pppp", 25, 3.34);
18         s[3] = new Student("hhhh", 12, 4.34);
19         s[4] = new Student("jjjj", 10, 5.34);
20         /*
21         System.out.println("排序前:");
22         displayArray(s);
23         */
24         System.out.println("按age进行非降序排序");
25         Arrays.sort(s, new SortByAge());
26         displayArray(s);
27         
28         System.out.println("按height进行非升序排序");
29         Arrays.sort(s, new SortByHeight());
30         displayArray(s);
31     }
32 }
33 
34 class Student {
35     private String name;
36     private int age;
37     private double height;
38     
39     public Student(String name, int age, double height) {
40         this.name = name;
41         this.age = age;
42         this.height = height;
43     }
44     
45     public String toString() {
46         return "Name: " + name + " Age: " + age + " Height: " + height;
47     }
48     
49     public int getAge() {
50         return age;
51     }
52     
53     public double getHeight() {
54         return height;
55     }
56 }
57 
58 /*
59  * 按age进行非降序排序
60  */
61 class SortByAge implements Comparator<Student> {
62     @Override
63     public int compare(Student o1, Student o2) {
64         if (o1.getAge() <= o2.getAge()) {
65             return -1;
66         }
67         return 1;
68     }
69 }
70 
71 /*
72  * 按height进行非升序排序
73  */
74 class SortByHeight implements Comparator<Student> {
75     @Override
76     public int compare(Student o1, Student o2) {
77         if (o1.getHeight() - o2.getHeight() < 0.01) {
78             return 1;
79         }
80         return -1;
81     }
82     
83 }

View Code

运行结果如下：