Java自定义 sort 排序方法

Sort用法

•结构

 1 package Test;
 2
 3 import java.util.Arrays;
 4 import java.util.Random;
 5 import java.util.Scanner;
 6
 7 public class TestSort {
 8
 9     static int a[] = new int[10];
10     static Random random = new Random();
11     static Scanner cin = new Scanner(System.in);
12
13     public static void main(String[] args) {
14
15     }
16
17     public static void Print(int[] a,int len) {
18         for(int i = 0;i < len;i++)
19             System.out.print(a[i]+" ");
20         System.out.println();
21     }
22 }

•Arrays.sort(a)

 1 public static void main(String[] args) {
 2
 3     for(int i = 0;i <= 5;i++) {
 4         a[i] = random.nextInt(10);
 5     }
 6
 7     Print(a,a.length);///只对 a[0,1,2,...,5] 区间进行了赋值操作，a[6,7,8,...,a.length-1]全为 0
 8     Arrays.sort(a);///对 a 中 [0,a.length) 区间进行升序排列
 9     Print(a,a.length);
10 }    

•运行结果

　　

•Arrays.sort(a,x,y)

 1 public static void main(String[] args) {
 2
 3     for(int i = 0;i <= 5;i++) {
 4         a[i] = random.nextInt(10)+1;
 5     }
 6
 7     Print(a,a.length);///只对 a[0,1,2,...,5] 区间进行了赋值操作，a[6,7,8,...,a.length-1]全为 0
 8     Arrays.sort(a,0,6);///对 a 中 [0,6) 区间进行升序排列
 9     Print(a,a.length);
10 }

•运行结果

　　

---

自定义Sort排序

•对数组自定义排序

1 ///对 num [1,n+1)区间进行自定义排序
2 Arrays.sort(num,1,n+1,new Comparator<Integer>() {
3     public int compare(Integer o1,Integer o2) {
4         return o1-o2;///从小到大排序
5         //return o2-o1;///从大到小排序
6     }
7 });

　　PS : Arrays.sort所排序的是对象类型，如果对int类型的数组进行sort排序，那就需要通过包装类 Integer 来实现。

　　所以 num 是 Integer 类型的数组。

•牛刀小试HDU2020

　　链接：绝对值排序

•Code

 1 import java.util.Arrays;
 2 import java.util.Comparator;
 3 import java.util.Random;
 4 import java.util.Scanner;
 5
 6 public class Main{
 7
 8     static int n;
 9     static Integer num[] = new Integer[150];
10     public static void main(String[] args) {
11
12         Scanner cin = new Scanner(System.in);
13
14         while(cin.hasNext()) {
15             n = cin.nextInt();
16             if(n == 0)
17                 break;
18
19             for(int i = 1;i <= n;i++) {
20                 num[i] = cin.nextInt();
21             }
22
23             Arrays.sort(num,1,n+1,new Comparator<Integer>(){
24                 @Override
25                 public int compare(Integer o1, Integer o2) {
26                     // TODO Auto-generated method stub
27                     return Math.abs(o2)-Math.abs(o1);
28                 }
29
30             });
31             for(int i = 1;i <= n;i++) {
32                 if(i != 1)
33                     System.out.print(" ");
34                 System.out.print(num[i]);
35             }
36             System.out.println();
37         }
38     }
39
40 }

•对Class自定义排序

 1 class F{
 2     int x,y;
 3 }
 4 class cmp implements Comparator<F>{
 5
 6     @Override
 7     public int compare(F o1, F o2) {
 8         // TODO Auto-generated method stub
 9         if(o1.x != o2.x) {//先按 x 从小到达排序
10             return o1.x > o2.x ? 1:-1;
11         }
12         else//x 相同，按照 y 从小到大排序
13             return o1.y > o2.y ? 1:-1;
14     }
15 }

•Code

 1 package Test;
 2
 3 import java.util.Arrays;
 4 import java.util.Comparator;
 5 import java.util.Random;
 6 import java.util.Scanner;
 7
 8 public class TestSortClass {
 9
10     static F[] f = new F[5];
11     static Random random = new Random();
12     static Scanner cin = new Scanner(System.in);
13
14     public static void main(String[] args) {
15
16         for(int i = 0;i < 5;i++) {
17             f[i] = new F();
18             f[i].x = random.nextInt(5);
19             f[i].y = random.nextInt(10);
20         }
21
22         Print(f,f.length);
23         Arrays.sort(f,0,5,new cmp());
24         Print(f,f.length);
25     }
26
27     private static void Print(F[] f,int len) {
28         // TODO Auto-generated method stub
29         System.out.println("**********");
30         for(int i = 0;i < len;i++) {
31             System.out.println(f[i].x + " " + f[i].y);
32         }
33     }
34 }
35
36 class F{
37     int x,y;
38 }
39 class cmp implements Comparator<F>{
40
41     @Override
42     public int compare(F o1, F o2) {
43         // TODO Auto-generated method stub
44         if(o1.x != o2.x) {//先按 x 从小到达排序
45             return o1.x > o2.x ? 1:-1;
46         }
47         else//x 相同，按照 y 从小到大排序
48             return o1.y > o2.y ? 1:-1;
49     }
50 }

运行结果：

　　

•牛刀小试HDU2022

　　链接：海选女主角

•Code

 1 import java.util.Arrays;
 2 import java.util.Comparator;
 3 import java.util.Scanner;
 4
 5 public class HDU2022 {
 6
 7     static int m,n;
 8     static F[] f = new F[10000];
 9     public static void main(String[] args){
10         Scanner cin = new Scanner(System.in);
11
12         while(cin.hasNext()) {
13             m = cin.nextInt();
14             n = cin.nextInt();
15
16             int index = 0;
17             for(int i = 1;i <= m;i++) {
18                 for(int j = 1;j <= n;j++) {
19                     f[index] = new F();
20                     f[index].point = cin.nextLong();
21                     f[index].x = i;
22                     f[index].y = j;
23                     index++;
24                 }
25             }
26             Arrays.sort(f,0,index,new cmp());
27
28             System.out.println(f[0].x+" "+f[0].y+" "+f[0].point);
29         }
30     }
31 }
32 class F{
33     long point;
34     int x,y;
35 }
36 class cmp implements Comparator<F>{
37
38     @Override
39     public int compare(F o1, F o2) {
40         if(o1.point != o2.point)//按照得分的绝对值从大到小排序
41             return Math.abs(o2.point) > Math.abs(o1.point) ? 1:-1;
42         else if(o1.x != o2.x) {//按照行从小到大排序
43             return (o1.x > o2.x)  ? 1:-1;
44         }
45         else {//按照列从小到大排序
46             return (o1.y > o2.y)  ? 1:-1;
47         }
48     }
49 }