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 }