question: private String hashKeyFromUrl ( String url ) { String key ; try { final MessageDigest mDigest = MessageDigest . getInstance ( "MD5" ) ; mDigest . update ( url . getBytes ( ) ) ; key = bytesToHexString ( mDigest . digest ( ) ) ; } catch ( NoSuchAlgorithmException ex ) { key = String . valueOf ( url . hashCode ( ) ) ; } return key ; }
target:  Method - Transfer url to key