Java Program Using indexOf Command

Spec Sheet

Program Title: Java Program Using indexOf Command
Purpose: To demonstrate the use of the indexOf method in Java for finding the position of a substring within a string.
Inputs: A main string and a substring entered by the user.
Outputs: The position of the first occurrence of the substring in the main string or a message if the substring is not found.
Key Features:

• Utilizes Java's indexOf method.
• Handles cases where the substring is not present.
• Interactive console input for user engagement.

Pseudo Code

1. Start
2. Prompt the user to input the main string.
3. Prompt the user to input the substring to search for.
4. Use the `indexOf` method on the main string to find the substring's position.
5. If `indexOf` returns a value >= 0, display the position to the user.
6. If `indexOf` returns -1, display a "not found" message.
7. End
    

Java Code

import java.util.Scanner;

public class IndexOfExample {
    public static void main(String[] args) {
        // Create a scanner object for input
        Scanner scanner = new Scanner(System.in);

        // Step 2: Prompt the user for the main string
        System.out.println("Enter the main string:");
        String mainString = scanner.nextLine();

        // Step 3: Prompt the user for the substring
        System.out.println("Enter the substring to search for:");
        String subString = scanner.nextLine();

        // Step 4: Use the indexOf method
        int position = mainString.indexOf(subString);

        // Step 5 & 6: Check if the substring is found
        if (position >= 0) {
            System.out.println("The substring "" + subString + "" is found at position: " + position);
        } else {
            System.out.println("The substring "" + subString + "" was not found in the main string.");
        }

        // Close the scanner
        scanner.close();
    }
}
    

Sample Output

Input:
Main string: Hello, welcome to the Java world!
Substring: Java

Output:
The substring "Java" is found at position: 18

Input:
Main string: Hello, welcome to the Java world!
Substring: Python

Output:
The substring "Python" was not found in the main string.