MorseCoder with "DEBUG" output

MorseCoder.java

package programming.set9.morses;

import java.nio.charset.Charset;

public class MorseCoder
{
	private static boolean DEBUG = false;

	/**
	 * Simple static test of the morse encode/decode functions
	 * 
	 * @param args
	 *            program arguments
	 */
	public static void main(String[] args)
	{
		String hell0W0rld = encode("Thi(s§ ju)mßbl!ed me+#s*#s");
		System.out.println(hell0W0rld);
		System.out.println(decode(hell0W0rld));
	}

	/**
	 * All required Chars offset by 0x30 (ASCII value of 0) with a few filler
	 * characters to fill the gap between 9 and A
	 */
	private static final String[] charToMorse = { "-----", ".----", "..---", "...--",
			"....-", ".....", "-....", "--...", "---..", "----.", "", "", "", "", "", "",
			"", ".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---",
			"-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-",
			"...-", ".--", "-..-", "-.--", "--.." };

	/**
	 * Returns a new string which is the morse code version of the input string.
	 * Each word is on a separate line. The morse representation of each
	 * character of the input string is separated from the next by a space
	 * character in the output string.
	 * 
	 * @param input
	 *            the input string.
	 * @return the morse code version of the input string, ignoring all
	 *         characters in the input string that cannot be represented in
	 *         international morse code.
	 */
	public static String encode(String input)
	{
		if(DEBUG) throw new RuntimeException("Encode: " + input);
		// Wipe all invalid characters off the face of the earth
		input = input.replaceAll("[^A-Za-z0-9\n ]", "");
		String morse = "";
		for(String word : input.split("[ \\n]+"))
		{
			for(byte c : word.toUpperCase().getBytes(Charset.forName("US-ASCII")))
			{
				int index = c - '0';
				// Check if the morse code table contains our char
				if(index >= 0 && index < charToMorse.length &&
						charToMorse[index].length() != 0)
				{
					morse += charToMorse[index] + " ";

				}
			}
			morse = morse.trim() + "\n";
		}
		return morse;
	}

	/**
	 * Returns a new string which is the natural-language version of the input
	 * string, which is assumed to be in morse code format as produced by the
	 * encode method.
	 * 
	 * @param input
	 *            morse code input string.
	 * @return natural language version or {@code null} if the input string
	 *         could not be properly parsed.
	 */
	public static String decode(String input)
	{
		String output = "";
		for(String word : input.split("\\n"))
		{
			for(String morse : word.split(" +"))
			{
				Character c = morseToChar(morse);
				// Break if the morse code contains any invalid sequences
				if(c == null) return null;
				output += c;
			}
			output += " ";
		}
		// Remove any unwanted whitespace characters
		return output.trim();
	}

	/**
	 * Searches the morse code table for a the given morse code and returns the
	 * corresponding char or {@code null} if the morse code wasn't found
	 * 
	 * @param str
	 *            The code to search
	 * @return The corresponding character or {@code null} if the morse code
	 *         wasn't found
	 */
	static private Character morseToChar(String str)
	{
		// Search the lookup table for str
		for(int i = 0; i < charToMorse.length; i++)
		{
			if(charToMorse[i].equals(str)) return (char) ('0' + i);
		}
		return null;
	}
}