From MD5-string to byte array

Hi fellows, I'm writing a simple cracker for MD5. The hash value has to be passed at command line as argument.
e.g.
java Cracker 0cc175b9c0f1b6a831c399e269772661In order to decode the hash value I'm using a brute force approach: therefore I compare a series of strings with the hash value by using the method of the class MessageDigest isEqual(byte[] a, byte[] b). So I encode each string and compare the byte array I get with the byte array of the hash value.
Here it comes the trouble I'm in:
when I try to get a bytes array of the MD5 hash value passed as argument of the program , I do get something, but it's not something that the isEqual method of MessageDigest can use to compare. As a result any attempt during the execution of brute force fails, even though the key is one of the string being checked.
Perhaps am I facing a format problem? Any idea?
Sorry for my english, it's not my first language
Thanks to whoever will help

Almost all questions in these forums about brute force attack on MD5 (or SHA1 or SHA256 etc etc etc) are school, college or university projects and of no practical use. This is almost certainly such a project.
Unless things have changed in the last year, there is no practical brute force attack on MD5 whereby an input can be generated from an arbitrary output even though two inputs with the same output can be fabricated. A dictionary attack is feasible if no salt is used or a known salt is used since one only has to build the dictionary for one salt value. If a different salt is used for each entry being attacked then a dictionary will be need for each salt being used. Of course if one takes the simple precaution of not using anything that is likely to be in a dictionary then the dictionary attack will likely fail.

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