Example: Octal to Binary Converter in Java

// Octal to Binary Converter
import java.util.Scanner;

// Main class containing the entry point of the program
public class Main {
    public static void main(String[] args) {
        // Step 1: Create a Scanner object to read user input
        Scanner scanner = new Scanner(System.in);

        // Step 2: Prompt the user to enter an octal number
        System.out.print("Enter an octal number: ");
        String octalNumber = scanner.nextLine();

        // Step 3: Initialize a StringBuilder to store the binary equivalent
        StringBuilder binaryNumber = new StringBuilder();

        // Step 4: Iterate through each character (digit) of the octal number
        for (int i = 0; i < octalNumber.length(); i++) {
            char octalDigit = octalNumber.charAt(i);

            // Step 5: Use a switch statement to convert each octal digit to its 3-bit binary equivalent
            switch (octalDigit) {
                case '0':
                    binaryNumber.append("000");
                    break;
                case '1':
                    binaryNumber.append("001");
                    break;
                case '2':
                    binaryNumber.append("010");
                    break;
                case '3':
                    binaryNumber.append("011");
                    break;
                case '4':
                    binaryNumber.append("100");
                    break;
                case '5':
                    binaryNumber.append("101");
                    break;
                case '6':
                    binaryNumber.append("110");
                    break;
                case '7':
                    binaryNumber.append("111");
                    break;
                default:
                    // Handle invalid octal digits
                    System.out.println("Invalid octal digit: " + octalDigit);
                    scanner.close();
                    return; // Exit the program if an invalid digit is found
            }
        }

        // Step 6: Print the resulting binary number
        System.out.println("Binary equivalent: " + binaryNumber.toString());

        // Step 7: Close the scanner
        scanner.close();
    }
}