Sequential MD5 generator

Generator.java

import java.io.FileWriter;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Generator {

	final protected static char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();
	final static String LINE_SEPARATOR = System.getProperty("line.separator");
	final static MessageDigest MD5;
	
	static {
		MessageDigest digest = null;
		try {
			digest = MessageDigest.getInstance("MD5");
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} finally {
			MD5 = digest;
		}
	}
	
	public static void main(String[] args) throws IOException {
		outputGeneratedMD5("D:\\zero_padded_numbers.txt");
	}

	private static void outputGeneratedMD5(String output) throws IOException {
		long timestamp = System.currentTimeMillis();
		FileWriter fileWriter = new FileWriter(output);
		for (int i = 0; i < 100000000; i++) {
			String source = String.format("%08d", i);
			byte[] sourceArray = source.getBytes();
			String line = generateMD5(sourceArray) + ":" + source + LINE_SEPARATOR;
			fileWriter.append(line);
		}
		fileWriter.close();
		System.out.println("Generation took " + (System.currentTimeMillis() - timestamp) + " ms");
	}
	
	private static String generateMD5(byte[] plaintText) {
		byte[] digest = MD5.digest(plaintText);
		return bytesToHex(digest);
	}
	
	private static String bytesToHex(byte[] bytes) {
	    char[] hexChars = new char[bytes.length * 2];
	    for ( int j = 0; j < bytes.length; j++ ) {
	        int v = bytes[j] & 0xFF;
	        hexChars[j * 2] = HEX_ARRAY[v >>> 4];
	        hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
	    }
	    return new String(hexChars);
	}
}