Converting number to words in Java. Is there an easier and more efficient way to do it?

Question

Hi guys i'm trying to write a simple program using control structures to convert numbers to words but the program is becoming way too long. Is there a simpler way to write it? An example is, if a user inputs 123 the output should be one two three. I didn't complete it but here is a sample:

import java.util.Scanner;
public class Number10 {

public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    String num;

    System.out.print("Enter a number and i'll convert it to words: ");
    num = input.nextLine();

    if((num.length()) == 1)
    {
        switch(num)
        {
        case "0":
        {
            System.out.print("Zero");
            break;
        }
        case "1":
        {
            System.out.print("One");
            break;
        }
        case "2":
        {
            System.out.print("Two");
            break;
        }
        case "3":
        {
            System.out.print("Three");
            break;
        }
        case "4":
        {
            System.out.print("Four");
            break;
        }
        case "5":
        {
            System.out.print("Five");
            break;
        }
        case "6":
        {
            System.out.print("Six");
            break;
        }
        case "7":
        {
            System.out.print("Seven");
            break;
        }
        case "8":
        {
            System.out.print("Eight");
            break;
        }
        case "9":
        {
            System.out.print("Nine");
            break;
        }
        default:
        {
            System.out.print("Please enter a number");
            break;
        }
        }
 }
    else if((num.length()) == 2)
    {
        switch(num)
        {
        case "11":
        {
            System.out.print("One One");
            break;
        }
        case "12":
        {
            System.out.print("One Two");
            break;
        }
        case "13":
        {
            System.out.print("One Three");
            break;
        }
        case "14":
        {
            System.out.print("One Four");
            break;
        }
        case "15":
        {
            System.out.print("One Five");
            break;
        }
        case "16":
        {
            System.out.print("One Six");
            break;
        }
        case "17":
        {
            System.out.print("One Seven");
            break;
        }
        case "18":
        {
            System.out.print("One Eight");
            break;
        }
        case "19":
        {
            System.out.print("One Nine");
            break;
        }
        case "20":
        {
            System.out.print("Two Zero");
            break;
        }
        case "21":
        {
            System.out.print("Two One");
            break;
        }
        case "22":
        {
            System.out.print("Two Two");
            break;
        }
        case "23":
        {
            System.out.print("Two Three");
            break;
        }
        case "24":
        {
            System.out.print("Two Four");
            break;
        }

        default:
        {
            System.out.print("Please enter a number");
            break;
        }
        }
    }

    else
    {
        System.out.print("Invalid number");
    }

}

}

Please help me out. Thanks.

Answer 1

I would do this:

import java.util.Scanner;
public class Number10 {

private static String[] nums = new String[]
        {"Zero", "One", "Two", "Three", "Four",
         "Five", "Six", "Seven", "Eight", "Nine"};

public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    String num;

    System.out.print("Enter a number and i'll convert it to words: ");
    num = input.nextLine();
    input.close()

    for (Character c: num.toCharArray())
        System.out.print(nums[Character.getNumericValue(c)]+ ' ');

}

Answer 2

First of all, you could create a

java.util.Map<Integer, String>

holding a mapping of integer values to string representations, but this will only shorten your code. The next step would be to handle numbers by digits, so you might hold a map of digit to string representation and print the string representation for each digit:

Map<Integer, String> numbers = new HashMap<Integer, String>();
numbers.put(0, "Zero");
// 22 = numbers.get(2) + " " + numbers.get(2);
// 51 = numbers.get(5) + " " + numbers.get(1);
// ...

Answer 3

It's much better to do this with a HashMap<Integer,String> . This makes for cleaner code and for more flexibility. If, for instance, you want to add functionality for other languages as well.

Use a loop to fill the HashMap with .put() , perhaps from a file. Then use .get() to retrieve the translations.