To implement Java Programs using Strings

Explanation

This Java program is designed to take a string input from the user, reverse the order of its characters, and then convert all characters in the reversed string to uppercase.

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

1. Set up Input: It first creates a Scanner object, which is a utility in Java used to read input from various sources, in this case, the standard input (keyboard).
2. Prompt for Input: The program then displays a message "Enter a string: " on the console, prompting the user to type something.
3. Read Input: Whatever the user types until they press Enter is read as a single line and stored in a String variable named input.
4. Initialize Reversed String: An empty String variable called reversed is created. This variable will be used to build the reversed version of the input string.
5. Reverse Loop: A for loop is used to iterate through the characters of the input string.
   • The loop starts from the last character of the input string (index input.length() - 1).
   • It continues as long as the index i is greater than or equal to 0 (meaning it goes down to the first character).
   • In each iteration, input.charAt(i) extracts the character at the current index i.
   • This character is then appended (+=) to the reversed string. Because the loop starts from the end and goes backward, characters are added to reversed in reverse order.
6. Convert to Uppercase: After the loop finishes, the reversed string now holds the input string in reverse order. The toUpperCase() method is called on this reversed string, which returns a new string where all characters are converted to their uppercase equivalents. This new string is stored in the result variable.
7. Display Output: Finally, the program prints the result string to the console, preceded by the label "Reversed and Uppercase String: ".
8. Close Scanner: The scanner.close() method is called to release the system resources associated with the Scanner object.

Algorithm

1. Start.
2. Create a Scanner object to read input from the console.
3. Display a prompt asking the user to "Enter a string: ".
4. Read the entire line of text entered by the user and store it in a String variable named input.
5. Initialize an empty String variable named reversed.
6. Begin a for loop that iterates from the last character's index of input (input.length() - 1) down to 0.
7. Inside the loop, for each iteration:
   • Retrieve the character at the current index i from the input string using input.charAt(i).
   • Append this character to the reversed string.
8. After the loop completes, call the toUpperCase() method on the reversed string to convert all its characters to uppercase. Store this new string in a variable named result.
9. Print the result string to the console, prefixed with "Reversed and Uppercase String: ".
10. Close the Scanner object to release resources.
11. End.