Chapter 9, Problem 9.1PE

(The Rectangle class) Following the example of the Circle class in Section 9.2, design a class named Rectangle to represent a rectangle. The class contains:

• Two double data fields named width and height that specify the width and height of the rectangle. The default values are 1 for both width and height.
• A no-arg constructor that creates a default rectangle.
• A constructor that creates a rectangle with the specified width and height.
• A method named getArea() that returns the area of this rectangle.
• A method named getPerimeter() that returns the perimeter.

Draw the UML diagram for the class then implement the class. Write a test program that creates two Rectangle objects- one with width 4 and height 40, and the other with width 3. 5 and height 35. 9. Display the width, height, area, and perimeter of each rectangle in this order.

Program Plan Intro

Rectangle

Program plan:

• Import required packages.
• Declare the main class named “Main”.
  • Give the main method “public static void main ()”.
    • Create an object “myRectangle” and pass the arguments.
    • Print the area of the first rectangle along with width and height by calling the function “getArea()”
    • Print the perimeter of the first rectangle by calling the function “getPerimeter()”
    • Create another object “yourRectangle” and also pass the arguments.
    • Print the area of the second rectangle along with width and height by calling the function “getArea()”
    • Print the perimeter of the second rectangle by calling the function “getPerimeter()”
• Define class named “MyRectangle”
  • Declare the data members and default constructor.
  • Declare a parameterized constructor.
    • Define a method “getArea()” to calculate the area of the rectangle.
    • Return the result.
    • Define a method “getPerimeter()” to calculate the perimeter of the rectangle.
    • Return the result.

Program Description Answer

The below program is used to display the area and perimeter of the two rectangles along with the width and height of the rectangles.

Explanation of Solution

Program:

// Class definition

public class One {

// Define main function

public static void main(String[] args) {

/*Create object for the class and pass the arguments */

MyRectangle myRectangle = new MyRectangle(4, 40);

// Print the area of the first rectangle

System.out.println("The area of a rectangle with width " + myRectangle.width + " and height "

+ myRectangle.height + " is " + myRectangle.getArea());

// Print the perimeter of the first rectangle

System.out.println("The perimeter of a rectangle is " + myRectangle.getPerimeter());

/* Create object for the class and pass the arguments */

MyRectangle yourRectangle = new MyRectangle(3.5, 35.9);

// Print the area of the second rectangle

System.out.println("The area of a rectangle with width " + yourRectangle.width + " and height "

+ yourRectangle.height + " is " + yourRectangle.getArea());

// Print the perimeter of the second rectangle

System.out.println("The perimeter of a rectangle is " + yourRectangle.getPerimeter());

}

}

// Class definition

class MyRectangle {

// Data members

double width = 1;

double height = 1;

// Default Constructor

public MyRectangle() {

}

// Parameterized Constructor

public MyRectangle(double newWidth, double newHeight) {

width = newWidth;

height = newHeight;

}

// Method to get the area of rectangle

public double getArea() {

/* Return the area value by multiplying width and height */

return width * height;

}

// Method to get the perimeter of rectangle

public double getPerimeter() {

/*Return the perimeter value by multiplying 2 with width and height */

return 2 * (width + height);

}

}

Sample Output

The area of a rectangle with width 4.0 and height 40.0 is 160.0

The perimeter of a rectangle is 88.0

The area of a rectangle with width 3.5 and height 35.9 is 125.64999999999999

The perimeter of a rectangle is 78.8