question: private static byte [ ] concatBytes ( byte [ ] array1 , byte [ ] array2 ) { byte [ ] cBytes = new byte [ array1 . length + array2 . length ] ; try { System . arraycopy ( array1 , 0 , cBytes , 0 , array1 . length ) ; System . arraycopy ( array2 , 0 , cBytes , array1 . length , array2 . length ) ; } catch ( Exception e ) { throw new RuntimeException ( e ) ; } return cBytes ; }
target:  This method concatenates two byte arrays