Binary to Octal Conversion Program

import java.util.Scanner;

public class BinaryToOctalConverter {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // Prompt the user to enter a binary number
        System.out.print("Enter a binary number: ");
        String binaryNumber = scanner.nextLine();

        // Validate if the input is a valid binary number
        if (!isValidBinary(binaryNumber)) {
            System.out.println("Invalid binary number.");
        } else {
            // Convert binary to octal
            String octalNumber = binaryToOctal(binaryNumber);
            System.out.println("Octal equivalent: " + octalNumber);
        }

        scanner.close();
    }

    // Function to check if a string is a valid binary number
    public static boolean isValidBinary(String binary) {
        // A valid binary number consists of only 0s and 1s
        return binary.matches("^[01]+$");
    }

    // Function to convert a binary number to octal
    public static String binaryToOctal(String binary) {
        // Pad the binary number to make its length a multiple of 3
        int length = binary.length();
        int padding = (3 - (length % 3)) % 3;
        StringBuilder paddedBinary = new StringBuilder(binary);
        for (int i = 0; i < padding; i++) {
            paddedBinary.insert(0, '0');
        }

        StringBuilder octal = new StringBuilder();
        int index = 0;

        // Convert the binary number to octal in groups of 3 bits
        while (index < paddedBinary.length()) {
            String group = paddedBinary.substring(index, index + 3);
            int decimalValue = Integer.parseInt(group, 2);
            octal.append(Integer.toOctalString(decimalValue));
            index += 3;
        }

        return octal.toString();
    }
}