math - Converting words to numbers in Java

Question

I have seen a lot of algorithms in which you give them a number say "123" and it converts it to One hundred twenty three. But I can't seem to find something that does the opposite, and the ones I did find only do it up to the number 1000. Can anyone direct me in the correct way as what I could do to create a method that takes "One thousand two hundred and thirty four" and gives back "1234"

Answer 1

I hope below code will do the job in most of the cases. However some modification might be required as I've not tested properly yet.

Assumption:

1. Positive, negative, plus, minus is not allowed.
2. Lac, crore is not allowed.
3. Only English language is supported.

If you need to support first two points, you can very easily do that.

    boolean isValidInput = true;
    long result = 0;
    long finalResult = 0;
    List<String> allowedStrings = Arrays.asList
    (
    "zero","one","two","three","four","five","six","seven",
    "eight","nine","ten","eleven","twelve","thirteen","fourteen",
    "fifteen","sixteen","seventeen","eighteen","nineteen","twenty",
    "thirty","forty","fifty","sixty","seventy","eighty","ninety",
    "hundred","thousand","million","billion","trillion"
    );

    String input="One hundred two thousand and thirty four";

    if(input != null && input.length()> 0)
    {
        input = input.replaceAll("-", " ");
        input = input.toLowerCase().replaceAll(" and", " ");
        String[] splittedParts = input.trim().split("\s+");

        for(String str : splittedParts)
        {
            if(!allowedStrings.contains(str))
            {
                isValidInput = false;
                System.out.println("Invalid word found : "+str);
                break;
            }
        }
        if(isValidInput)
        {
            for(String str : splittedParts)
            {
                if(str.equalsIgnoreCase("zero")) {
                    result += 0;
                }
                else if(str.equalsIgnoreCase("one")) {
                    result += 1;
                }
                else if(str.equalsIgnoreCase("two")) {
                    result += 2;
                }
                else if(str.equalsIgnoreCase("three")) {
                    result += 3;
                }
                else if(str.equalsIgnoreCase("four")) {
                    result += 4;
                }
                else if(str.equalsIgnoreCase("five")) {
                    result += 5;
                }
                else if(str.equalsIgnoreCase("six")) {
                    result += 6;
                }
                else if(str.equalsIgnoreCase("seven")) {
                    result += 7;
                }
                else if(str.equalsIgnoreCase("eight")) {
                    result += 8;
                }
                else if(str.equalsIgnoreCase("nine")) {
                    result += 9;
                }
                else if(str.equalsIgnoreCase("ten")) {
                    result += 10;
                }
                else if(str.equalsIgnoreCase("eleven")) {
                    result += 11;
                }
                else if(str.equalsIgnoreCase("twelve")) {
                    result += 12;
                }
                else if(str.equalsIgnoreCase("thirteen")) {
                    result += 13;
                }
                else if(str.equalsIgnoreCase("fourteen")) {
                    result += 14;
                }
                else if(str.equalsIgnoreCase("fifteen")) {
                    result += 15;
                }
                else if(str.equalsIgnoreCase("sixteen")) {
                    result += 16;
                }
                else if(str.equalsIgnoreCase("seventeen")) {
                    result += 17;
                }
                else if(str.equalsIgnoreCase("eighteen")) {
                    result += 18;
                }
                else if(str.equalsIgnoreCase("nineteen")) {
                    result += 19;
                }
                else if(str.equalsIgnoreCase("twenty")) {
                    result += 20;
                }
                else if(str.equalsIgnoreCase("thirty")) {
                    result += 30;
                }
                else if(str.equalsIgnoreCase("forty")) {
                    result += 40;
                }
                else if(str.equalsIgnoreCase("fifty")) {
                    result += 50;
                }
                else if(str.equalsIgnoreCase("sixty")) {
                    result += 60;
                }
                else if(str.equalsIgnoreCase("seventy")) {
                    result += 70;
                }
                else if(str.equalsIgnoreCase("eighty")) {
                    result += 80;
                }
                else if(str.equalsIgnoreCase("ninety")) {
                    result += 90;
                }
                else if(str.equalsIgnoreCase("hundred")) {
                    result *= 100;
                }
                else if(str.equalsIgnoreCase("thousand")) {
                    result *= 1000;
                    finalResult += result;
                    result=0;
                }
                else if(str.equalsIgnoreCase("million")) {
                    result *= 1000000;
                    finalResult += result;
                    result=0;
                }
                else if(str.equalsIgnoreCase("billion")) {
                    result *= 1000000000;
                    finalResult += result;
                    result=0;
                }
                else if(str.equalsIgnoreCase("trillion")) {
                    result *= 1000000000000L;
                    finalResult += result;
                    result=0;
                }
            }

            finalResult += result;
            result=0;
            System.out.println(finalResult);
        }
    }