question: public static String hashKeyForDisk ( String key ) { String cacheKey ; try { final MessageDigest mDigest = MessageDigest . getInstance ( "MD5" ) ; mDigest . update ( key . getBytes ( ) ) ; cacheKey = bytesToHexString ( mDigest . digest ( ) ) ; } catch ( NoSuchAlgorithmException e ) { cacheKey = String . valueOf ( key . hashCode ( ) ) ; } return cacheKey ; }
target:  A hashing method that changes a string (like a URL) into a hash suitable for using as a disk filename.