private byte[] concat(byte[] arrayA,byte[] arrayB){
  byte[] result=new byte[arrayA.length + arrayB.length];
  System.arraycopy(arrayA,0,result,0,arrayA.length);
  System.arraycopy(arrayB,0,result,arrayA.length,arrayB.length);
  return result;
}

private byte [ ] concat ( byte [ ] arrayA , byte [ ] arrayB ) { byte [ ] result = new byte [ arrayA . length + arrayB . length ] ; System . arraycopy ( arrayA , 0 , result , 0 , arrayA . length ) ; System . arraycopy ( arrayB , 0 , result , arrayA . length , arrayB . length ) ; return result ; }
concatenate two byte arrays .
