用JAVA写一个函数交换两个数字

前几天面试，问到了这个题目，写了个程序测试了下，直接交换和用包装了交换都不能交换两个数的值，而采用数组交换和成员变量交换是可以做到的

 

package com.wq.swap;

public class SwapNumbers {
	public int a;
	public int b;
	
	//包装类交换
	public static void swap (Integer a, Integer b) {	
		Integer temp = a;
		a = b;
		b = temp;
	};
	
	//直接交换
	public static void swap (int a, int b) {	
		int temp = a;
		a = b;
		b = temp;
	};
	
	//数组
	public static void swap (int[] arr) {	
		int temp = arr[0];
		arr[0] = arr[1];
		arr[1] = temp;
	};
	
	//成员对象
	public  void swapNum(int a, int b) {	
		this.a = b;
		this.b = a;
	};
	
	//包装类打印
	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);
	}
	//对象打印
	public  void print() {
		System.out.println("a=" + this.a + " b=" + this.b);
	}
	//数组打印
	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("------直接交换----------");
		int a = 2, b = 3;
		
		print(a,b);
		swap(a, b);
		print(a,b);
		
		System.out.println("------包装类交换----------");
		Integer m = new Integer(2);
		Integer n = new Integer(3);
		
		print(m,n);
		swap(m, n);
		print(m,n);
		
		System.out.println("-------数组交换---------");
		int[] arr = {2,3};
		print(arr);
		swap(arr);
		print(arr);
		
		System.out.println("-------成员变量交换---------");
		print(a,b);
		SwapNumbers sn = new SwapNumbers();
		sn.swapNum(a, b);
		sn.print();
		
	}
}

------直接交换----------
a=2 b=3
a=2 b=3
------包装类交换----------
m=2 n=3
m=2 n=3
-------数组交换---------
2 3 
3 2 
-------成员变量交换---------
a=2 b=3
a=3 b=2