This is the code I wrote where base class is shape and there are 3 methods for the shape area using same keyword but different parameters, and in the main I have 1 class for each shape and which is derived from the shape class, but after running the main method I get a blank output with exit code.

package com.company;
import java.util.Scanner;

class Shape {
    int b, h, s;
    double r;

    //triangle method
    void area(int base, int height) {
        int triArea = (base * height)/2;
        System.out.println("Area of Triangle = "   triArea);
    }

    //square method
    void area(int side) {
        int sqrArea = side * side;
        System.out.println("Area of Square = "   sqrArea);
    }

    //circle method
    void area(double radius) {
        double cirArea = Math.PI * radius * radius;
        System.out.println("Area of circle = "   cirArea);
    }
}

public class Area {
    public static void main(String[] args) {
        class Triangle extends Shape{
            void takeInput(){
                Scanner cin = new Scanner(System.in);
                System.out.println("Enter base of Triangle: ");
                this.b = cin.nextInt();

                System.out.println("Enter height of Triangle: ");
                this.h = cin.nextInt();
                area(b, h);
            }
        }

        class Square extends Shape{
            void takeInput(){
                Scanner cin = new Scanner(System.in);
                System.out.println("Enter side of Square: ");
                this.s = cin.nextInt();
                area(s);
            }
        }

        class Circle extends Shape{
            void takeInput(){
                Scanner cin = new Scanner(System.in);
                System.out.print("Enter radius of Circle: ");
                this.r = cin.nextDouble();
                area(r);
            }
        }
    }
}

CodePudding user response：

you just defined the Classes you also need to make a Objekt with those classes

Circle c = new Circle();
c.takeInput();

CodePudding user response：

Maybe it's better to use an abstract method in Shape. Something like the following:

abstract class Shape {
    abstract void area(double... params);
}

and

public class Circle extends Shape {

    public static void main(String[] args) {
        Circle c = new Circle();
        double radius = 1;
        c.area(radius);
    }

    @Override
    void area(double... params) {
        if (params.length != 1) {
            throw new IllegalArgumentException("Expected one argument as parameter (the radius).");
        }
        System.out.println("Circle area: "   (Math.PI * Math.pow(params[0], 2)));

    }

}