CharUtils.java

package stu.tnt;

public class CharUtils {
	/**
	 * <p>
	 * Converts the character to the Integer it represents, throwing an
	 * exception if the character is not numeric.
	 * </p>
	 * 
	 * <p>
	 * This method coverts the char '1' to the int 1 and so on.
	 * </p>
	 * 
	 * <pre>
	 *   CharUtils.toIntValue('3')  = 3
	 *   CharUtils.toIntValue('A')  throws IllegalArgumentException
	 * </pre>
	 * 
	 * @param ch
	 *            the character to convert
	 * @return the int value of the character
	 * @throws IllegalArgumentException
	 *             if the character is not ASCII numeric
	 */
	public static int toIntValue(char ch) {
		if (isAsciiNumeric(ch) == false) {
			throw new IllegalArgumentException("The character " + ch
					+ " is not in the range '0' - '9'");
		}
		return ch - 48;
	}

	/**
	 * <p>
	 * Checks whether the character is ASCII 7 bit numeric.
	 * </p>
	 * 
	 * <pre>
	 *   CharUtils.isAsciiNumeric('a')  = false
	 *   CharUtils.isAsciiNumeric('A')  = false
	 *   CharUtils.isAsciiNumeric('3')  = true
	 *   CharUtils.isAsciiNumeric('-')  = false
	 *   CharUtils.isAsciiNumeric('\n') = false
	 *   CharUtils.isAsciiNumeric('©') = false
	 * </pre>
	 * 
	 * @param ch
	 *            the character to check
	 * @return true if between 48 and 57 inclusive
	 */
	public static boolean isAsciiNumeric(char ch) {
		return ch >= '0' && ch <= '9';
	}
}