simple hex dump in Java

hexdump.java

public static String hexdump(byte[] data) {
	final int perRow = 16;

	final String hexChars = "0123456789ABCDEF";
	StringBuilder dump = new StringBuilder();
	StringBuilder chars = null;
	for (int i = 0; i < data.length; i++) {
		int offset = i % perRow;
		if (offset == 0) {
			chars = new StringBuilder();
			dump.append(String.format("%04x", i))
				.append("  ");
		}

		int b = data[i] & 0xFF;
		dump.append(hexChars.charAt(b >>> 4))
			.append(hexChars.charAt(b & 0xF))
			.append(' ');

		chars.append((char) ((b >= ' ' && b <= '~') ? b : '.'));

		if (i == data.length - 1 || offset == perRow - 1) {
			for (int j = perRow - offset - 1; j > 0; j--)
				dump.append("-- ");
			dump.append("  ")
				.append(chars)
				.append('\n');
		}
	}
	return dump.toString();
}