class Point{ double x,y; public: double getx() {return x;} double gety() {return y;} void setx(double a) { x = a;} void sety(double a) { y = a;} Point(double a,double b):x(a),y(b){} ~Point(){} };

这是一个 C++ 类 Point，表示二维平面上的一个点。该类有两个私有属性 x 和 y，表示点的横坐标和纵坐标。类中定义了四个公有方法：getx 和 gety 用来获取点的横坐标和纵坐标，setx 和 sety 用来设置点的横坐标和纵坐标。类中还定义了一个构造函数 Point(double a,double b)，用来初始化 Point 类的对象，同时还定义了一个析构函数 ~Point()。

相关问题

仔细阅读以下所给的代码,完善Point类,在Point类中覆盖Object的toString()和equals()方法，使得编译执行主类Test输出如下结果: public class Test{ public static void main(String[] args){ Point pt1=new Point(12,24,36); Point pt2=new Point(12,24,36); System.out.println("pt1:"+pt1); System.out.println("pt1.equals(pt2):"+ pt1.equals(pt2)); } } class Point{ private double x; private double y; private double z; public Point(){} public Point(double x,double y,double z){ this.x=x; this.y=y; this.z=z; } public double getX(){return this.x;} public void setX(double x){this.x=x;} public double getY(){return this.y;} public void setY(double y){this.y=y;} }

完善后的代码如下：

public class Test{
	public static void main(String[] args){
		Point pt1=new Point(12,24,36);
		Point pt2=new Point(12,24,36);
		System.out.println("pt1:"+pt1);
		System.out.println("pt1.equals(pt2):"+ pt1.equals(pt2));
    }
}

class Point{
	private double x;
	private double y;
	private double z;
	
	public Point(){}
	
	public Point(double x,double y,double z){
		this.x=x;
		this.y=y;
		this.z=z;
	}
	
	public double getX(){return this.x;}
	public void setX(double x){this.x=x;}
	
	public double getY(){return this.y;}
	public void setY(double y){this.y=y;}
	
	public double getZ(){return this.z;}
	public void setZ(double z){this.z=z;}
	
	@Override
	public String toString() {
		return "Point [x=" + x + ", y=" + y + ", z=" + z + "]";
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		Point other = (Point) obj;
		if (Double.doubleToLongBits(x) != Double.doubleToLongBits(other.x))
			return false;
		if (Double.doubleToLongBits(y) != Double.doubleToLongBits(other.y))
			return false;
		if (Double.doubleToLongBits(z) != Double.doubleToLongBits(other.z))
			return false;
		return true;
	}
}

输出结果为：

pt1:Point [x=12.0, y=24.0, z=36.0]
pt1.equals(pt2):true

其中，Point类中覆盖了Object的toString()和equals()方法，toString()方法返回一个字符串，表示该点的x、y、z坐标值，equals()方法判断两个Point对象是否相等，如果它们的x、y、z坐标值都相等，则返回true，否则返回false。在测试主类Test中，创建了两个Point对象pt1和pt2，它们的坐标值都相等，因此调用equals()方法返回true。在输出pt1时，调用了Point类的toString()方法，返回了该点的x、y、z坐标值。

1)设计其抽象子类二维图形（TwoDGraph），添加计算面积calArea()和周长calPerimeter()两个抽象方法； 2)从TwoDGraph类派生出圆形Circle，增加圆心centerPoint和半径radius属性，增加构造方法； 3)在Circle中重写calArea、calPerimeter和toString()方法 4)从TwoDGraph类派生出长方形Rectangle，增加左上角坐标leftPoint、长length和宽width属性，增加构造方法； 5)在Rectangle中重写calArea、calPerimeter和toString()方法 6)在Rectangle新增输出4个顶点坐标方法outputPoints() 7)在main方法中，测试Circle和Rectangle类中的方法。 public abstract class Graph { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } public String toString() { return ""; } } public class Point { private double x; private double y; public Point() { this(0,0); } public Point (double x,double y) { this.x = x; this.y = y; } public double getX() { return x; } public void setX(double x) { this.x = x; } public double getY() { return y; } public void setY(double y) { this.y = y; } public String toString() { return String.format("[%.2f, %.2f]", x,y); } }

好的，这是一个关于Java的面向对象编程的问题。以下是代码实现：

public abstract class TwoDGraph extends Graph {
    public abstract double calArea();
    public abstract double calPerimeter();
}

public class Circle extends TwoDGraph {
    private Point centerPoint;
    private double radius;

    public Circle(String name, Point centerPoint, double radius) {
        setName(name);
        this.centerPoint = centerPoint;
        this.radius = radius;
    }

    public double calArea() {
        return Math.PI * radius * radius;
    }

    public double calPerimeter() {
        return 2 * Math.PI * radius;
    }

    public String toString() {
        return "Circle " + getName() + ": center = " + centerPoint.toString() + ", radius = " + radius;
    }
}

public class Rectangle extends TwoDGraph {
    private Point leftPoint;
    private double length;
    private double width;

    public Rectangle(String name, Point leftPoint, double length, double width) {
        setName(name);
        this.leftPoint = leftPoint;
        this.length = length;
        this.width = width;
    }

    public double calArea() {
        return length * width;
    }

    public double calPerimeter() {
        return 2 * (length + width);
    }

    public String toString() {
        return "Rectangle " + getName() + ": left point = " + leftPoint.toString() + ", length = " + length + ", width = " + width;
    }

    public void outputPoints() {
        Point rightPoint = new Point(leftPoint.getX() + length, leftPoint.getY());
        Point bottomPoint = new Point(leftPoint.getX(), leftPoint.getY() - width);
        Point diagonalPoint = new Point(leftPoint.getX() + length, leftPoint.getY() - width);
        System.out.println("The four points of " + getName() + " are:");
        System.out.println(leftPoint.toString() + ", " + rightPoint.toString() + ", " + bottomPoint.toString() + ", " + diagonalPoint.toString());
    }
}

public class Test {
    public static void main(String[] args) {
        Circle circle = new Circle("c1", new Point(0,0), 5);
        System.out.println(circle.toString());
        System.out.println("Area: " + circle.calArea());
        System.out.println("Perimeter: " + circle.calPerimeter());

        System.out.println();

        Rectangle rectangle = new Rectangle("r1", new Point(0,0), 5, 3);
        System.out.println(rectangle.toString());
        System.out.println("Area: " + rectangle.calArea());
        System.out.println("Perimeter: " + rectangle.calPerimeter());
        rectangle.outputPoints();
    }
}

在这个代码实现中，我们首先创建了一个抽象的二维图形类TwoDGraph，它包含了计算面积和周长的抽象方法。然后我们从TwoDGraph中派生出了圆形类Circle和长方形类Rectangle。这两个类都实现了抽象方法，同时也重写了toString方法以便于输出信息。在Rectangle类中，我们还新增了输出四个顶点坐标的方法outputPoints。最后，在main方法中，我们对Circle和Rectangle类中的方法进行了测试。