Question

Each class must have private instance fields that store the specific shapes dimensions.
Each class must have a constructor that supplies the dimensions.
Each class must have an area() function.
Each class must have a toString() function that returns strings like these, as appropriate:
∗ triangle (base = 1.00, height = 2.00)
∗ rectangle (width = 1.00, height = 1.00)
∗ square (side = 1.00)
∗ circle (radius = 1.00)
All numbers are rounded to two decimal places.

Write a Main class that works like this:
$ java Main
?triangle 1.0 2.0
Area of triangle (base = 1.00, height = 2.00) = 1.00
? rectangle 1.0 2.0
Area of rectangle (width = 1.00, height = 2.00) = 2.00
? square 1.0
Area of square (side = 1.00) = 1.00
? circle 1.0
Area of circle (radius = 1.00) = 3.14
? quit
$

It does not need to handle bad user input.
Hint: Your Main class will be simpler if you exploit inclusion polymorphism. Have a single variable
of type Shape, instead of many variables with different types.

Answer 1

Answer on Question#54253, Programming / Java | JSP | JSF

TESTShape.java

public class TestShape {
    public static void main(String[] args) {
        // Rectangle test
        double width = 5.00, length = 7.00;
        Shape rectangle = new Rectangle(width, length);
        System.out.print("\nRectangle width %.2f %.2f: ",width,length);
        System.out.print("\nResulting area: %.2f: ", rectangle.area());
        // Square test
        double side = 5.00;
        Shape square = new Square(side);
        System.out.print("\nSquare side %.2f: ", side);
        System.out.print("\nResulting area: %.2f: ", square.area());
        // Circle test
        double radius = 5.00;
        Shape circle = new Circle(radius);
        System.out.print("\nCircle radius: %.2f ", radius);
        System.out.print("\nResulting Area: %.2f ", circle.area());
        // Triangle test
        double base = 5.00, height = 4.00;
        Shape triangle = new Triangle(base,height);
        System.out.print("\nTriangle base and height %.2f %.2f: ",base,height);
        System.out.print("\nResulting area: %.2f: ", triangle.area());
    }
}

Square.java

public abstract class Shape {
    public abstract double area();
}

Square.java

public class Square extends Shape {
    private final double side; //sides
    public Square() {
        this(1);
    }
    public Square(double side) {
        this.side = side;
    }
    @Override
    public double area() {
        // A = l * l
        return side*side;
    }
}

Circle.java

public class Circle extends Shape {
    private final double radius;
    final double pi = Math.PI;
    public Circle() {
        this(1);
    }
    public Circle(double radius) {
        this.radius = radius;
    }
    @Override
    public double area() {
        return pi * Math.pow(radius, 2);
    }
}

//////////////////////

Triangle.java

public class Triangle extends Shape {
    private final double base, height;
    public Triangle() {
        this(1,1);
    }
    public Triangle(double base, double height) {
        this.base = base;
        this.height = height;
    }
    @Override
    public double area() {
        double s = 0.5*base*height;
        return s;
    }
}

////////////////////

Rectangle.java

public class Rectangle extends Shape {
    private final double width, length; //sides
    public Rectangle() {
        this(1,1);
    }
    public Rectangle(double width, double length) {
        this.width = width;
        this.length = length;
    }
    @Override
    public double area() {
        // A = w * l
        return width * length;
    }
}

////////////////////

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