Java交换两个数字

Posted 2021-03-14 海恋天

一.四种方式交换两个数字

• 直接交换：失败
• 包装类交换：失败
• 数组方式交换：成功
• 成员变量交换：成功

 1 public class SwapNumbers {
 2     public int a;
 3     public int b;
 4     
 5     //包装类交换
 6     public static void swap (Integer a, Integer b) {    
 7         Integer temp = a;
 8         a = b;
 9         b = temp;
10     }
11     
12     //直接交换
13     public static void swap (int a, int b) {    
14         int temp = a;
15         a = b;
16         b = temp;
17     }
18     
19     //数组
20     public static void swap (int[] arr) {    
21         int temp = arr[0];
22         arr[0] = arr[1];
23         arr[1] = temp;
24     }
25     
26     //成员对象
27     public  void swapNum(int a, int b) {    
28         this.a = b;
29         this.b = a;
30     }
31     
32     //包装类打印
33     public static void print(Integer m, Integer n) {
34         System.out.println("m=" + m.intValue() + " n=" + n.intValue());
35     }
36     //直接打印
37     public static void print(int a, int b) {
38         System.out.println("a=" + a + " b=" + b);
39     }
40     //对象打印
41     public  void print() {
42         System.out.println("a=" + this.a + " b=" + this.b);
43     }
44     //数组打印
45     public static void print(int[] a) {
46         for (int i : a) {
47             System.out.print(i + " ");
48         }
49         System.out.println();
50     }
51     
52     
53     public static void main(String[] args) {
54         
55         System.out.println("------直接交换----------");
56         int a = 2, b = 3;
57         
58         print(a,b);
59         swap(a, b);
60         print(a,b);
61         
62         System.out.println("------包装类交换----------");
63         Integer m = new Integer(2);
64         Integer n = new Integer(3);
65         
66         print(m,n);
67         swap(m, n);
68         print(m,n);
69         
70         System.out.println("-------数组交换---------");
71         int[] arr = {2,3};
72         print(arr);
73         swap(arr);
74         print(arr);
75         
76         System.out.println("-------成员变量交换---------");
77         print(a,b);
78         SwapNumbers sn = new SwapNumbers();
79         sn.swapNum(a, b);
80         sn.print();
81         
82     }
83 }

结果：

 1 ------直接交换----------
 2 a=2 b=3
 3 a=2 b=3
 4 ------包装类交换----------
 5 m=2 n=3
 6 m=2 n=3
 7 -------数组交换---------
 8 2 3 
 9 3 2 
10 -------成员变量交换---------
11 a=2 b=3
12 a=3 b=2