NumberSayer.java

package nl.siegmann.epublib.utilities;

public class NumberSayer {

	private static final String[] NUMBER_BELOW_20 = new String[] {"zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "nineteen"}; 
	private static final String[] DECIMALS = new String[] {"zero", "ten", "twenty", "thirty", "fourty", "fifty", "sixty", "seventy", "eighty", "ninety"};
	private static final String[] ORDER_NUMBERS = new String[] {"hundred", "thousand", "million", "billion", "trillion"};
	
	
	public static String getNumberName(int number) {
		if(number < 0) {
			throw new IllegalArgumentException("Cannot handle numbers < 0 or > " + Integer.MAX_VALUE);
		}
		if(number < 20) {
			return NUMBER_BELOW_20[number];
		}
		if(number < 100) {
			return DECIMALS[number / 10] + NUMBER_BELOW_20[number % 10];
		}
		if(number >= 100 && number < 200) {
			return ORDER_NUMBERS[0] + getNumberName(number - 100);
		}
		if(number < 1000) {
			return NUMBER_BELOW_20[number / 100] + ORDER_NUMBERS[0] + getNumberName(number % 100);
		}
		throw new IllegalArgumentException("Cannot handle numbers < 0 or > " + Integer.MAX_VALUE);
	}
}