Expt 1 - Part 1, Part 2 & Part 3

Explanation

This Java program demonstrates how to take a numerical input from the user representing a day of the week (from 1 to 7) and then display the corresponding day's name. It utilizes the Scanner class to read user input and a switch statement to efficiently handle multiple possible conditions based on the entered number.

Here's a step-by-step breakdown of the logic:

1. Import Scanner: The line import java.util.Scanner; brings in the Scanner class, which is essential for reading input from the user (like typing on the keyboard).
2. Class and Main Method: The code is enclosed within a class named prog13, and the execution begins in the main method, which is the entry point of any Java program.
3. Create Scanner Object: Scanner input = new Scanner(System.in); creates an object of the Scanner class, named input. This object is configured to read data from System.in, which represents the standard input stream (usually the keyboard).
4. Prompt User: System.out.print("Enter a number to get Day of the Week: "); displays a message on the console, asking the user to enter a number. System.out.print is used instead of println so that the cursor stays on the same line after the prompt, allowing the user to type their input directly after the message.
5. Read User Input: int num = input.nextInt(); reads the integer value entered by the user from the console and stores it in an integer variable named num.
6. Switch Statement: The switch(num) statement checks the value stored in the num variable. It then compares this value against a series of case labels.
   • Cases 1-7: If num matches any of the case values (1 through 7), the corresponding System.out.println() statement is executed, printing the name of the day. For example, if num is 3, it will print "Day of the week is Wednesday".
   • Break Statement: The break; statement after each case is crucial. It terminates the switch statement immediately after a matching case is found and its code is executed. Without break, the program would continue to execute the code in the subsequent case labels (this is called "fall-through"), which is usually not the desired behavior in this scenario.
   • Default Case: The default: case acts as a catch-all. If the value of num does not match any of the specified case values (1 through 7), the code within the default block is executed, printing "Invalid number".
7. Close Scanner: input.close(); closes the Scanner object. This is good practice as it releases the system resources associated with the scanner.

Algorithm

• Start the program.
• Import the Scanner class to enable user input.
• Create a Scanner object to read from the standard input.
• Prompt the user to enter a number between 1 and 7.
• Read the integer entered by the user and store it in a variable.
• Use a switch statement to evaluate the entered number:
  • If the number is 1, print "Monday".
  • If the number is 2, print "Tuesday".
  • If the number is 3, print "Wednesday".
  • If the number is 4, print "Thursday".
  • If the number is 5, print "Friday".
  • If the number is 6, print "Saturday".
  • If the number is 7, print "Sunday".
  • If the number is none of the above, print "Invalid number".
• Ensure that each case terminates after its execution using break.
• Close the Scanner object to release resources.
• End the program.