Expt 1 - Part 1, Part 2 & Part 3

Explanation

This Java program is designed to determine if a smaller sequence of characters, referred to as a "substring," is present within a larger sequence of characters, known as the "main string." It achieves this by first prompting the user to input the main string they wish to search within, followed by the specific substring they are looking for.

Once both strings are provided by the user, the program employs a built-in Java string method to efficiently check for the existence of the substring inside the main string. Based on the outcome of this check, it outputs a clear message indicating whether the substring was found or not. Finally, it ensures that the resources used for input are properly closed to prevent any leaks.

Algorithm

1. Start Program: Begin the execution of the Java application.
2. Initialize Scanner: Create an instance of the Scanner class, configured to read input from the standard input stream (console).
3. Prompt for Main String: Display a message to the user asking them to enter the main string.
4. Read Main String: Capture the user's input for the main string and store it in a String variable.
5. Prompt for Substring: Display a message to the user asking them to enter the substring.
6. Read Substring: Capture the user's input for the substring and store it in another String variable.
7. Check for Substring Existence: Utilize the contains() method of the mainString object to ascertain if the subString is present within it.
8. Conditional Output:
   • If the contains() method returns true (meaning the substring was found), print "Substring exists" to the console.
   • If the contains() method returns false (meaning the substring was not found), print "Substring does not exist" to the console.
9. Close Scanner: Close the Scanner object to release system resources associated with it.
10. End Program: Terminate the execution of the application.