public static void main(String[] args) {

    //Create a Scanner
    Scanner input = new Scanner(System.in);

    //Prompt user to enter any decimal number
    System.out.println("Enter a decimal number, please: ");
    int decNum = input.nextInt();

    int division = decNum;
    String allDigits = "";

    //Calculate the digitZero
    allDigits += setDigit(division);
    //Calculate the other digits
    do{
        division = division / 16;
        allDigits+=setDigit(division);
    } while (division >= 16);

    //Reverse the string into a normal hexadecimal view
    allDigits = new StringBuilder(allDigits).reverse().toString();
    //Display the result
    System.out.println("" + allDigits);
}

public static String setDigit(int Number) {
    int division = Number;
    int digit = division % 16;
    String hexDigits = "";
    if (digit > 9) {
        switch (digit) {
            case 10:
                hexDigits += "A";
            case 11:
                hexDigits += "B";
            case 12:
                hexDigits += "C";
            case 13:
                hexDigits += "D";
            case 14:
                hexDigits += "E";
            case 15:
                hexDigits += "F";
        }
    } else {
        hexDigits += Integer.toString(digit);
    }
    return hexDigits;
}