Expt 1 - Part 1, Part 2 & Part 3

Explanation

This Java code demonstrates the fundamental concepts of classes and objects. It defines a blueprint for a "Box" and then creates two instances of that box, assigning them different dimensions and calculating their volumes.

Here's a step-by-step breakdown:

1. class Box: This line declares a new class named Box. Think of a class as a template or a blueprint for creating objects. In this case, our blueprint is for a box.

2. double width; double height; double depth;: Inside the Box class, these lines declare instance variables (also called fields or attributes). These variables represent the properties that every Box object will have: its width, height, and depth. They are declared as double to allow for fractional dimensions.

3. void volume(){ ... }: This defines a method named volume within the Box class. A method is a set of instructions that an object can perform. This volume method calculates and prints the volume of the box.

   • System.out.print("Volume is ");: This line prints the text "Volume is " to the console without moving to the next line.
   • System.out.println(width * height * depth);: This line calculates the volume by multiplying the width, height, and depth of the specific Box object the method is called on. It then prints this calculated volume to the console and moves the cursor to the next line.

4. class BoxDemo3: This is another class that contains the main method, which is the entry point for any Java program.

5. public static void main(String args[]){ ... }: This is the main method.

   • Box mybox1 = new Box();: This line creates an object named mybox1 of the Box class. The new Box() part allocates memory for a new Box object and initializes its instance variables to their default values (0.0 for double).
   • Box mybox2 = new Box();: Similarly, this line creates a second Box object named mybox2.
   • mybox1.width = 2; mybox1.height = 4; mybox1.depth = 6;: These lines assign values to the instance variables of mybox1. We are setting the dimensions of the first box.
   • mybox2.width = 8; mybox2.height = 10; mybox2.depth = 12;: These lines assign values to the instance variables of mybox2, setting the dimensions for the second box.
   • mybox1.volume();: This line calls the volume method on the mybox1 object. The method will use the width, height, and depth values stored within mybox1 to calculate and print its volume.
   • mybox2.volume();: This line calls the volume method on the mybox2 object, using its own dimensions to calculate and print its volume.

In essence, the code defines a reusable structure for a "Box" and then uses that structure to create and manipulate multiple distinct "Box" objects.

Algorithm

• Define a class named Box to serve as a blueprint for box objects.
• Within the Box class, declare instance variables width, height, and depth of type double to store the dimensions of a box.
• Within the Box class, define a method named volume that:
  • Prints the string "Volume is ".
  • Calculates the product of width, height, and depth.
  • Prints the calculated volume to the console on a new line.
• Define a main class (BoxDemo3) containing the program's entry point.
• Inside the main method:
  • Create an instance (object) of the Box class named mybox1.
  • Create another instance (object) of the Box class named mybox2.
  • Assign specific values to the width, height, and depth instance variables of mybox1.
  • Assign different specific values to the width, height, and depth instance variables of mybox2.
  • Call the volume method on the mybox1 object.
  • Call the volume method on the mybox2 object.