Java: Appendable byte array

Question

I want to append bytes to an byte array. The result should be type byte[], with adding single byte's after calculating them, to it. So my question is: What is the best and/or efficient way to accomplish that? How to write to that?

I found the following link http://stackoverflow.com/questions/5368704/appending-a-byte-to-the-end-of-another-byte thought it could help. — user3245329, Jul 03 '14 at 21:23
the number of bytes may vary and is unknown at initialisation. — luckydonald, Jul 03 '14 at 22:05

score 5 · Accepted Answer · answered Jul 03 '14 at 21:19

5

Use ByteArrayOutputStream. This has a toByteArray() method when you are done

http://docs.oracle.com/javase/7/docs/api/java/io/ByteArrayOutputStream.html

answered Jul 03 '14 at 21:19

Strikeskids

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score 0 · Answer 2 · answered Apr 22 '15 at 14:45

I would suggest using of Guava's ByteSource

http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/io/ByteSource.html

It is much more efficient because of using a chains of small chunks inside instead of reallocating memory for a huge array (as ByteArrayOutputStream does).

Here is an example:

byte[] buffer = new byte[1024]; 

List<ByteSource> loaded = new ArrayList<ByteSource>();

    while (true) {
        int read = input.read(buffer);
        if (read == -1) break;
        loaded.add(ByteSource.wrap(Arrays.copyOf(buffer, read)));
    }

ByteSource result = ByteSource.concat(loaded)

Java: Appendable byte array

2 Answers2