How to combine two byte arrays [duplicate]

Solution 1:

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 < combined.length; ++i)
{
    combined[i] = i < 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<Byte> list = new ArrayList<Byte>(Arrays.<Byte>asList(one));
list.addAll(Arrays.<Byte>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();

Solution 2:

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);

Solution 3:

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;
}