How to combine two byte arrays

Question

I have two byte arrays and I am wondering how I would go about adding one to the other or combining them to form a new byte array

User · Answer

The simplest method  inline  assuming a and b are two given arrays    byte   c    new String a  cch    new String b  cch   getBytes cch     This  of course  works with more than two summands and uses a concatenation charset  defined somewhere in your code   static final java nio charset Charset cch   java nio charset StandardCharsets ISO 8859 1    Or  in more simple form  without this charset   byte   c    new String a   l1     new String b   l1    getBytes  l1      But you need to suppress UnsupportedEncodingException which is unlikely to be thrown     The fastest method   public static byte   concat byte   a  byte   b        int lenA   a length      int lenB   b length      byte   c   Arrays copyOf a  lenA   lenB       System arraycopy b  0  c  lenA  lenB       return c

User · Answer

String temp   passwordSalt  byte   byteSalt   temp getBytes    int start   32  for  int i   0  i  lt  byteData length  i           byteData start   i    byteSalt i       The problem with your code here is that the variable i that is being used to index the arrays is going past both the byteSalt array and the byteData array   So  Make sure that byteData is dimensioned to be at least the maximum length of the passwordSalt string plus 32   What will correct it is replacing the following line   for  int i   0  i  lt  byteData length  i       with   for  int i   0  i  lt  byteSalt length  i

User · Answer

I think it is best approach   public static byte   addAll final byte   array1  byte   array2        byte   joinedArray   Arrays copyOf array1  array1 length   array2 length       System arraycopy array2  0  joinedArray  array1 length  array2 length       return joinedArray

User · Answer

You re just trying to concatenate the two byte arrays   byte   one   getBytesForOne    byte   two   getBytesForTwo    byte   combined   new byte one length   two length    for  int i   0  i  lt  combined length    i        combined i    i  lt  one length   one i    two i - one length       Or you could use System arraycopy   byte   one   getBytesForOne    byte   two   getBytesForTwo    byte   combined   new byte one length   two length    System arraycopy one 0 combined 0          one length   System arraycopy two 0 combined one length two length     Or you could just use a List to do the work   byte   one   getBytesForOne    byte   two   getBytesForTwo     List lt Byte gt  list   new ArrayList lt Byte gt  Arrays  lt Byte gt asList one    list addAll Arrays  lt Byte gt asList two     byte   combined   list toArray new byte list size        Or you could simply use ByteBuffer with the advantage of adding many arrays   byte   allByteArray   new byte one length   two length   three length    ByteBuffer buff   ByteBuffer wrap allByteArray   buff put one   buff put two   buff put three    byte   combined   buff array

User · Answer

You can do this by using Apace common lang package  org apache commons lang ArrayUtils class    You need to do the following  byte   concatBytes   ArrayUtils addAll one two

User · Answer

Assuming your byteData array is biger than 32   byteSalt length     you re going to it s length  not byteSalt length  You re trying to copy from beyond the array end

User · Answer

I ve used this code which works quite well just do appendData and either pass a single byte with an array  or two arrays to combine them    protected byte   appendData byte firstObject byte   secondObject       byte   byteArray   firstObject       return appendData byteArray secondObject      protected byte   appendData byte   firstObject byte secondByte       byte   byteArray   secondByte       return appendData firstObject byteArray      protected byte   appendData byte   firstObject byte   secondObject       ByteArrayOutputStream outputStream   new ByteArrayOutputStream         try           if  firstObject  null  amp  amp  firstObject length  0              outputStream write firstObject           if  secondObject  null  amp  amp  secondObject length  0                 outputStream write secondObject         catch  IOException e            e printStackTrace              return outputStream toByteArray

[java] How to combine two byte arrays

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