Java交換兩個數字

一.四種方式交換兩個數字

• 直接交換：失敗
• 包裝類交換：失敗
• 數組方式交換：成功
• 成員變量交換：成功

public class SwapNumbers {
    public int a;
    public int b;
    
    //包裝類交換
    public static void swap (Integer a, Integer b) {    
        Integer temp = a;
        a = b;
        b = temp;
    }
    
    //直接交換
    public static void swap (int a, int b) {    
        int temp = a;
        a = b;
        b = temp;
    }
    
    //數組
    public static void swap (int[] arr) {    
        int temp = arr[0];
        arr[0] = arr[1];
        arr[1] = temp;
    }
    
    //成員對象
    public  void swapNum(int a, int b) {    
        this.a = b;
        this.b = a;
    }
    
    //包裝類打印
    public static void print(Integer m, Integer n) {
        System.out.println("m=" + m.intValue() + " n=" + n.intValue());
    }
    //直接打印
    public static void print(int a, int b) {
        System.out.println("a=" + a + " b=" + b);
    }
    //對象打印
    public  void print() {
        System.out.println("a=" + this.a + " b=" + this.b);
    }
    //數組打印
    public static void print(int[] a) {
        for (int i : a) {
            System.out.print(i + " ");
        }
        System.out.println();
    }
    
    
    public static void main(String[] args) {
        
        System.out.println("------直接交換----------");
        int a = 2, b = 3;
        
        print(a,b);
        swap(a, b);
        print(a,b);
        
        System.out.println("------包裝類交換----------");
        Integer m = new Integer(2);
        Integer n = new Integer(3);
        
        print(m,n);
        swap(m, n);
        print(m,n);
        
        System.out.println("-------數組交換---------");
        int[] arr = {2,3};
        print(arr);
        swap(arr);
        print(arr);
        
        System.out.println("-------成員變量交換---------");
        print(a,b);
        SwapNumbers sn = new SwapNumbers();
        sn.swapNum(a, b);
        sn.print();
        
    }
}

結果：

------直接交換----------
a=2 b=3
a=2 b=3
------包裝類交換----------
m=2 n=3
m=2 n=3
-------數組交換---------
2 3 
3 2 
-------成員變量交換---------
a=2 b=3
a=3 b=2