Random string unique hash generator

randhashgenerator.java

private static char[] VALID_CHARACTERS =
			"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456879".toCharArray();

	public static String csRandomAlphaNumericString(int numChars) throws Exception{
		SecureRandom srand = new SecureRandom();
		Random rand = new Random();
		char[] buff = new char[numChars];

		for (int i = 0; i < numChars; ++i) {
			if ((i % 10) == 0) {
				rand.setSeed(srand.nextLong());
			}
			buff[i] = VALID_CHARACTERS[rand.nextInt(VALID_CHARACTERS.length)];
		}
		return new String(buff);
	}