CODEWITHSUNDEEP
javainheritancesubclasssuperclass
slowdev
slowdev

Reputation: 3

calling methods of subclass

I'm trying to learn inheritance. I have a superclass called Shape with getColor and getFilled methods. I then have 3 subclasses called Triangle, Rectangle and Circle. In each of the subclasses I have methods getPerimeter and getArea. Each shape has a subclass that extends the superclass. I then create an ArrayList and add a Triangle, Rectangle and Circle. I can call the getColor and getFilled superclass methods but run into a problem when trying to call the getPerimeter and getArea method that are created in the subclass. I think I have a misunderstanding of subclass and superclass. Here is my code:

Shape superclass

public class Shape
{
    // instance variables
    public String color; // color of shape
    public boolean filled; // shape fill status

    public Shape()
    {
        // initialize instance variables
        color = "";
        filled = false;
    }
    
    public String getColor()
    {
        return color;
    }
    
    public boolean getFilled()
    {
        return filled;
    }
    
    public String toString()
    {
        return getClass().getName();
    }
}

Triangle (did not include here the Circle/Rectangle because they are basically the same as triangle)

public class Triangle extends Shape
{
    // instance variables
    private double side1;
    private double side2;
    private double side3;

    public Triangle(String color, boolean filled, double side1, double side2, double side3)
    {
        // initialize instance variables
        super.color = color;
        super.filled = filled;
        this.side1 = side1;
        this.side2 = side2;
        this.side3 = side3;
    }
    
    public double getPerimeter() {
        return this.side1 + this.side2 + this.side3;
    }
    
    public double getArea() {
        return (this.side2 / 2.0) * this.side1;
    }
}

Tester:

import java.util.ArrayList;

public class Tester
{
    
    public static void main(String arg[])
    {
        ArrayList<Shape> shapes = new ArrayList<>(); // create new array list of shapes
        shapes.add(new Triangle("white", true, 3.0, 2.5, 2.0)); // Add new triangle to shapes list
        shapes.add(new Rectangle("red", true, 2.0, 4.0)); // Add new rectangle to shapes list
        shapes.add(new Circle("yellow", false, 1.0)); // Add new circle to shapes list
        System.out.println("Starting shapes\n");
        for (Shape shape: shapes) // loop through shapes
        {
            System.out.println(shape.toString()
                +"[color="+shape.getColor()+", filled="+shape.getFilled()+"]"
                ); // print out string of shape/color/fill
            System.out.println("Perimeter: "+shape.getPerimeter()); // print out perimeter
            System.out.println("Area: "+shape.getArea()); // print out perimeter
            System.out.println();
        }
    }
}

I expected to be able to call shape.getPerimeter() and shape.getArea() from the subclasses.

Upvotes: 0

Views: 116

Answers (1)

slowdev
slowdev

Reputation: 3

Added getPerimeter() and getArea() to parent Shape class, then added @Override in front of public class getPerimeter( and public class getArea( in all of the subclasses. Solved

Upvotes: 0

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