互换值

方法1：

public class Change {
    public static void change(int x,int y) {
        System.out.println("改变之前");
        System.out.println("x = "+x);
        System.out.println("y = "+y);
        int z;
        z = x;
        x = y;
        y = z;
        System.out.println("改变之后");
        System.out.println("x = "+x);
        System.out.println("y = "+y);
    }
    public static void main(String[] args) {
        change(3,4);
    }
}

方法2：

对于基本数据类型传递的是数据的拷贝，而对于引用数据类型传递的是引用的拷贝。

// 此类不像方法1那样是用一个临时变量来保存
public class Change {
    public static void change(int x,int y) {
        x = x + y;
        y = x - y;
        x = x - y;
    }

    public static void change(int[] num) {
        num[0] = num[0] + num[1];
        num[1] = num[0] - num[1];
        num[0] = num[0] - num[1];
    }

    public static void change(Point pt) {
        pt.x = pt.x + pt.y;
        pt.y = pt.x - pt.y;
        pt.x = pt.x - pt.y;
    }

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

        int[] num = {3,4};
        change(num);
        System.out.println("x = " + num[0]);
        System.out.println("y = " + num[1]);
        System.out.println();

        Point pt = new Point();
        pt.x = 3;
        pt.y = 4;
        change(pt);
        System.out.println("x = " + pt.x);
        System.out.println("y = " + pt.y);
    }
}

class Point {
    int x,y;
}