Question

我遇到了麻烦。我想用测试程序绘制矩形和圆形。但我运行它，它没有打印任何值。我想知道我应该为每个形状设置值。我需要帮助。

这是图类

public abstract class Figure{
    private int X, Y; // the center of the object.
    private String name;
    private static int numberOfShapes=0;

    public Figure(){
        X = 0;
        Y = 0;
        name = "none";
    }
    public Figure(int a, int b, String n){
        setX(a);
        setY(b);
        setName(n);
        numberOfShapes++;
    }
    public void setX(int a){X = a;}
    public void setY(int b){Y = b;}
    public void setName(String n){name = n;}
    public int getX(){return X;}
    public int getY(){return Y;}
    public String getName(){return name;}
    public static int getNumberOfShapes(){return numberOfShapes;}
    public abstract void erase();
    public abstract void draw();
    public void center(){
        System.out.println("\nIn Figure. Centering at ("+getX()+","+getY()+")");
    }

这是我的矩形类

public class Rectangle extends Figure {
    int length, height;
    public Rectangle(){
        super(0,0,"none");
        //setLength(0);
        //setHeight(0);
    }
    public Rectangle(String n,int a, int b, int h,int l){
        super(a,b,n);
        setLength(l);
        setHeight(h);
    }
    public String toString() {
        return "In Rectangle Drawing " + getName() + " centered at (" + getX() + "," + getY() + ") Length " + getLength() + " height " + getHeight();
    }
    public void erase(){
        System.out.println("In Rectangle erasing");
    }
    public void draw(){
        center();
        erase();
        System.out.println(""+this);
    }

    public void setLength(int l){length = l;}
    public void setHeight(int h){height = h;}
    public int getLength(){return length;}
    public int getHeight(){return height;}

}

My Circle Class

public class Circle extends Figure {
        private double Radius;
        public Circle(){
            super(0,0,"none");
        }
        public Circle(String n, int a, int b){
            super(a,b,n);
        }
        public double getArea() {
            return Math.PI * Radius * Radius;
        }

        public void setRadius(double r){
            Radius = r;
        }
        public String toString(){
            return "In Circle Drawing "+getName()+" centered at ("+getX()+","+getY()+") Area "+getArea();
        }
        public void erase(){
            System.out.println("In Circle erasing");
        }
        public void draw(){
            erase();
            System.out.println(""+this);
        }
        public void setRadius(int r){Radius = r;}
        public double getRadius(){return Radius;}



}

这是我的测试类

import java.util.*;

public class Testshape{
    public static void main(String[] args){
        //Scanner s = new Scanner(System.in);

        Rectangle r = new Rectangle();
        //Rectangle ry = new Rectangle();




        System.out.println("In Rectangle erasing");
        System.out.println(r);




    }
}

我的输出格式就像这样：

The Output

Answer 1

调用类的 toString（）方法以获取输出。你没有将任何参数传递给构造函数方法，所以我想知道这是否会编译。矩形的两侧是相同的，相对的宽度和长度相等。

public class Testshape{
public static void main(String[] args){
    //Scanner s = new Scanner(System.in);

    Rectangle r = new Rectangle("Rectangle",length, width);

    System.out.println("In Rectangle erasing");
    System.out.println(r.toString());

}

Answer 2

猜猜你错过了对draw()方法的调用。

import java.util.*;

public class Testshape{
    public static void main(String[] args){
        //Scanner s = new Scanner(System.in);

        Rectangle r = new Rectangle();
        //Rectangle ry = new Rectangle();

        r.draw();


        System.out.println("In Rectangle erasing");
        System.out.println(r);
    }
}

Answer 3

我没有在你的功能上看到任何消息调用。

你可能会为动作调用函数，你只是实例化了类，而你的构造函数没有做任何打印。

使用矩形和多边形的抽象多态性圆形形状类

3 个答案: