Question

java language

Problem 3: Shape (10 points) (Software Design) Create an abstract class that represents a Shape and contains abstract method: area and perimeter. Create concrete classes: Circle, Rectangle, Triangle which extend the Shape class and implements the abstract methods. A circle has a radius, a rectangle has width and height, and a triangle has three sides. Software Architecture: The Shape class is the abstract super class and must be instantiated by one of its concrete subclasses: Circle, Rectangle, or Triangle, which extends it. UML Object Diagram Shape CircleRecangleTriangle UML Class Diagram: Shape +area(): double + perimeter): double ·italicized class/method names within UML Class Diagram indicate abstract class/methods Shape Method API: Modifier and Type Method and Description abstract doublearea() Returns the area of this shape abstract double perimeter() Returns the perimeter of this shape UML Class Diagram: Circle - radius: double constructor (radius: double) + area): double tostring(): String +constructor) +perimeter(): double Italicized class/method names within UML Class Diagram indicate abstract class/methods Circle Constructor Summary: Constructor Circle (double radius) Circle() Description Creates a Circle with given radius Creates a Circle with radius 1 SalaryEmployee Method API: Modifier and Type Method and Description double area) Returns Math.PI (radius) perimeter() Returns 2 Math.PIradius tostring() Returns the String "Circle" double String UML Class Diagram: Rectangle width: double - length: double +constructor (width: double, length: double) +constructor () +area(): double + perimeter(): double toString(): String Italicized class/method names within UML Class Diagram indicate abstract class/methods Rectangle Constructor Summary: Constructor Rectangle (double width, double length) Creates a Rectangle with given length, width Rectangle() Description Creates a Rectangle with width 1, length 1 Rectangle Method API: Modifier and Type Method and Description double area() Returns width * length perimeter() Returns 2" (width + length) toString() Returns the String "Rectangle" double String UML Class Diagranm Triangle -a: double -b: double -C: double +constructor (a: double, b: double, c: double) +constructor() +area(): double +perimeter() double + toString(): String Italicized class/method names within UML Class Diagram indicate abstract class/methods Triangle Constructor Summary Constructor Triangle(double a, double b, double c) Creates a Triangle with given sides a, b, c Triangle() Description Creates a Triangle with all sides- 1 Triangle Method API Modifier and Type Method and Description double area() Returns area of triangle using heron's formula perimeter() Returns a b c toString() Returns the String "Triangle" double String Tester Files: Use the TestShape.java file to test your implementation. Compare your results with the TestShape.txt file Sample Method Calls Sample Method Results Shape[] shapesnew Shape[3]; shapes [0] new Circle(3); shapes [1]new Rectangle(4,2); shapes [2]-new Triangle (1,2,3); "Circle: area: 28.3, perimeter: 18.81n" "Rectangle: area: 8.0, perimeter: 12.01n" "Triangle: area: 0.0, perimeter: 6.01n" for (Shape polygon shapes) double areapolygon.area) double perimeter- polygon.perimeter); System .out.printf("%s: area: %.elf perimeter : %.81f\n", polygon, area, perimeter)

Answer 1

Code:

abstract class Shape
{
   abstract public double area(); //Method to be overridden
   abstract public double perimeter();  //Method to be overridden
}

class Circle extends Shape
{
   private double radius;
   public Circle(double radius)
   {
       this.radius=radius;
   }
   public Circle()
   {
       this.radius=0;
   }
   public double area()
   {
       return Math.PI*this.radius*this.radius;
   }
   public double perimeter()
   {
       return 2*Math.PI*this.radius;
   }
   public String toString()
   {
       return "Circle";
   }
}

class Rectangle extends Shape
{
   private double width,length;
   public Rectangle(double length,double width)
   {
       this.length=length;
       this.width=width;
   }
   public Rectangle()
   {
       this.width=0;
       this.length=0;
   }
   public double area()
   {
       return this.length*this.width;
   }
   public double perimeter()
   {
       return 2*(this.length+this.width);
   }
   public String toString()
   {
       return "Rectangle";  
   }
}

class Triangle extends Shape
{
   private double a,b,c;
   public Triangle(double a,double b,double c)
   {
       this.a=a;
       this.b=b;
       this.c=c;
   }
   public Triangle()
   {
       this.a=0;
       this.b=0;
       this.c=0;
   }
   public double area()
   {
       double s=0.5*(this.a+this.b+this.c);
       return Math.sqrt(s*(s-this.a)*(s-this.b)*(s-this.c));
   }
   public double perimeter()
   {
       return this.a+this.b+this.c;
   }
   public String toString()
   {
       return "Triangle";
   }
}

class Main
{
   public static void main(String[] args) { //Testing code
       Shape shapes[]=new Shape[3];
       shapes[0]=new Circle(3);
       shapes[1]=new Rectangle(4,2);
       shapes[2]=new Triangle(1,2,3);
       for(Shape polygon:shapes)
       {
           double area=polygon.area();
           double perimeter=polygon.perimeter();
           System.out.printf("%s: area: %.01f perimeter: %.01f\n",polygon,area,perimeter);
       }
   }
}

Sample i/o:

sushmanths-MacBook-Pro:Desktop sushmanth$ java Main Circle: area: 28.3 perimeter: 18.8 Rectangle: area: 8.0 perimeter: 12.0 Triangle: area: 8.0 perimeter: 6.0 sushmanths-MacBook-Pro:Desktop sushmanth$

Explanation:

Class Shape, Circle, Rectangle, Triangle is defined. The methods are and perimeter in the base class are overridden in the derived classes. Default and a parameterised constructor is given for all three derived classes. A test code is written using Main class and a sample i/o is attached for reference