JAVA经典基础问题

交换两个变量的值，如下方法是不行的：

public class change
{
    public static void main(String args[]){
        int x=3;
        int y=4;
        System.out.println("x="+x);
        System.out.println("y="+y+"/n");
        change.change(x,y);
        System.out.println("x="+x);
        System.out.println("y="+y+"/n");
    }
        public static void change (int x, int y) 
        { 
              x = x + y; 
              y = x - y; 
              x = x - y; 
        }
}

函数形参改变不了变量值，将函数代码直接写到主方法中：

public class chg
{
	public static void main(String args[]){
		int x=3;
		int y=4;
		System.out.println("x="+x);
		System.out.println("y="+y+"/n");
		int z;
			 z = x; 
			 x=y;
			  y = z; 
		System.out.println("x="+x);
		System.out.println("y="+y+"/n");
	}
		
}