Explanation

This Java code is designed to calculate the area of a rectangle. It's a straightforward program that demonstrates basic input, processing, and output operations in Java. Here's a step-by-step breakdown of what it does:

Importing the Scanner Class: import java.util.Scanner; This line imports the Scanner class from the java.util package. The Scanner class is a built-in Java utility that allows us to read input from various sources, such as the keyboard (standard input).
Defining the Class: class prog6{ ... } This defines a Java class named prog6. In Java, all executable code resides within classes.
Defining the Main Method: public static void main(String args[]){ ... } This is the entry point of the Java program. When you run this code, the Java Virtual Machine (JVM) starts execution from within this main method.
- public: This means the method can be accessed from anywhere.
- static: This means the method belongs to the prog6 class itself, not to any specific object of the class. You can call it directly using the class name.
- void: This indicates that the method does not return any value.
- main(String args[]): This is the standard signature for the main method. String args[] is an array of strings that can be used to pass command-line arguments to the program, though they are not used in this specific code.
Creating a Scanner Object: Scanner input = new Scanner(System.in); This line creates an object of the Scanner class named input. This object is then configured to read data from System.in, which represents the standard input stream (typically the keyboard).
Prompting for Length: System.out.print("Enter length of rectangle: "); This line displays the message "Enter length of rectangle: " on the console. System.out.print() prints the text without moving to the next line.
Reading Length Input: int l = input.nextInt(); This line reads the integer value that the user types in response to the prompt and stores it in an integer variable named l. input.nextInt() is a method of the Scanner object that reads the next integer token from the input.
Prompting for Breadth: System.out.print("Enter Breadth of rectangle: "); Similar to step 5, this displays a prompt for the user to enter the breadth of the rectangle.
Reading Breadth Input: int b = input.nextInt(); This line reads the integer value entered by the user for the breadth and stores it in an integer variable named b.
Calculating and Displaying the Area: System.out.println("Area of rectangle is: "+(l*b)); This is the core calculation and output step.
- l * b: This part multiplies the value stored in the l variable (length) by the value stored in the b variable (breadth) to calculate the area.
- "Area of rectangle is: " + (l*b): The + operator here is used for string concatenation. It joins the literal string "Area of rectangle is: " with the result of the multiplication (l*b).
- System.out.println(...): This method prints the concatenated string to the console and then moves the cursor to the next line.
Closing the Scanner: input.close(); This line is important for resource management. It closes the Scanner object, releasing any system resources it might be holding (like the input stream). It's good practice to close resources when you are finished with them.

In summary, the program interactively asks the user for the length and breadth of a rectangle, calculates their product (which is the area), and then displays the result to the user.

Algorithm

Start the program execution.
Import the Scanner class to enable reading user input.
Declare a class named prog6.
Define the main method, which is the program's entry point.
Create a Scanner object to read input from the console (System.in).
Prompt the user to enter the length of the rectangle.
Read the integer value entered by the user and store it in a variable named l.
Prompt the user to enter the breadth of the rectangle.
Read the integer value entered by the user and store it in a variable named b.
Calculate the area of the rectangle by multiplying l and b.
Display the calculated area to the user on the console, along with a descriptive message.
Close the Scanner object to release resources.
End the program execution.

Explanation

Importing the Scanner Class: import java.util.Scanner; This line imports the Scanner class from the java.util package. The Scanner class is a built-in Java utility that allows us to read input from various sources, such as the keyboard (standard input).
Defining the Class: class prog6{ ... } This defines a Java class named prog6. In Java, all executable code resides within classes.
Defining the Main Method: public static void main(String args[]){ ... } This is the entry point of the Java program. When you run this code, the Java Virtual Machine (JVM) starts execution from within this main method.
- public: This means the method can be accessed from anywhere.
- static: This means the method belongs to the prog6 class itself, not to any specific object of the class. You can call it directly using the class name.
- void: This indicates that the method does not return any value.
- main(String args[]): This is the standard signature for the main method. String args[] is an array of strings that can be used to pass command-line arguments to the program, though they are not used in this specific code.
Creating a Scanner Object: Scanner input = new Scanner(System.in); This line creates an object of the Scanner class named input. This object is then configured to read data from System.in, which represents the standard input stream (typically the keyboard).
Prompting for Length: System.out.print("Enter length of rectangle: "); This line displays the message "Enter length of rectangle: " on the console. System.out.print() prints the text without moving to the next line.
Reading Length Input: int l = input.nextInt(); This line reads the integer value that the user types in response to the prompt and stores it in an integer variable named l. input.nextInt() is a method of the Scanner object that reads the next integer token from the input.
Prompting for Breadth: System.out.print("Enter Breadth of rectangle: "); Similar to step 5, this displays a prompt for the user to enter the breadth of the rectangle.
Reading Breadth Input: int b = input.nextInt(); This line reads the integer value entered by the user for the breadth and stores it in an integer variable named b.
Calculating and Displaying the Area: System.out.println("Area of rectangle is: "+(l*b)); This is the core calculation and output step.
- l * b: This part multiplies the value stored in the l variable (length) by the value stored in the b variable (breadth) to calculate the area.
- "Area of rectangle is: " + (l*b): The + operator here is used for string concatenation. It joins the literal string "Area of rectangle is: " with the result of the multiplication (l*b).
- System.out.println(...): This method prints the concatenated string to the console and then moves the cursor to the next line.
Closing the Scanner: input.close(); This line is important for resource management. It closes the Scanner object, releasing any system resources it might be holding (like the input stream). It's good practice to close resources when you are finished with them.

In summary, the program interactively asks the user for the length and breadth of a rectangle, calculates their product (which is the area), and then displays the result to the user.

Expt 1 - Part 1, Part 2 & Part 3