定义Point类描述屏幕上的一个点。该类包括点的x和y两个坐标，及对点进行的相关操作，如：取得点的坐标值，对点的坐标进行赋值。此类属于MyPackageTwoD包。此包中另一个Rectangle类可以实现矩形的基本操作，包含Point、width、height等3个变量，及构造方法和其他方法。文件TestPackage.java中包含main()方法，

可以使用Point和Rectangle类，创建对象并测试其功能。以下是Point类的示例代码：

package MyPackageTwoD;

public class Point {
    private int x;
    private int y;

    // 构造方法
    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }

    // 获取x坐标
    public int getX() {
        return x;
    }

    // 获取y坐标
    public int getY() {
        return y;
    }

    // 设置x坐标
    public void setX(int x) {
        this.x = x;
    }

    // 设置y坐标
    public void setY(int y) {
        this.y = y;
    }
}

以下是Rectangle类的示例代码：

package MyPackageTwoD;

public class Rectangle {
    private Point origin;
    private int width;
    private int height;

    // 构造方法
    public Rectangle(Point origin, int width, int height) {
        this.origin = origin;
        this.width = width;
        this.height = height;
    }

    // 获取左上角的点
    public Point getOrigin() {
        return origin;
    }

    // 获取宽度
    public int getWidth() {
        return width;
    }

    // 获取高度
    public int getHeight() {
        return height;
    }

    // 设置左上角的点
    public void setOrigin(Point origin) {
        this.origin = origin;
    }

    // 设置宽度
    public void setWidth(int width) {
        this.width = width;
    }

    // 设置高度
    public void setHeight(int height) {
        this.height = height;
    }

    // 获取矩形面积
    public int getArea() {
        return width * height;
    }

    // 判断点是否在矩形内
    public boolean contains(Point p) {
        return p.getX() >= origin.getX() && p.getX() <= origin.getX() + width
                && p.getY() >= origin.getY() && p.getY() <= origin.getY() + height;
    }
}

以下是TestPackage.java的示例代码：

package MyPackageTwoD;

public class TestPackage {
    public static void main(String[] args) {
        // 创建一个点对象
        Point p1 = new Point(2, 3);
        System.out.println("Point p1: (" + p1.getX() + ", " + p1.getY() + ")");

        // 改变点的坐标
        p1.setX(5);
        p1.setY(7);
        System.out.println("Point p1: (" + p1.getX() + ", " + p1.getY() + ")");

        // 创建一个矩形对象
        Rectangle rect = new Rectangle(new Point(1, 2), 5, 4);
        System.out.println("Rectangle origin: (" + rect.getOrigin().getX() + ", " + rect.getOrigin().getY() + ")");
        System.out.println("Rectangle width: " + rect.getWidth());
        System.out.println("Rectangle height: " + rect.getHeight());
        System.out.println("Rectangle area: " + rect.getArea());

        // 判断一个点是否在矩形内
        Point p2 = new Point(3, 4);
        System.out.println("Point p2 is inside the rectangle: " + rect.contains(p2));
        Point p3 = new Point(6, 5);
        System.out.println("Point p3 is inside the rectangle: " + rect.contains(p3));
    }
}

运行TestPackage.java，输出如下：

Point p1: (2, 3)
Point p1: (5, 7)
Rectangle origin: (1, 2)
Rectangle width: 5
Rectangle height: 4
Rectangle area: 20
Point p2 is inside the rectangle: true
Point p3 is inside the rectangle: false