ByteArrayOutPutSteam to Byte[] not working as expected

Question

I need to make a Byte[] out of a ByteArrayOutputStream, but this is not working. When I log the outcome of baos.toByteArray(); it only shows me eleven characters, no matter which file I try to upload, the log entry looks like this: [B@544641ab

This is the code:

    final ByteArrayOutputStream baos = new ByteArrayOutputStream(); // Stream to write to
    upload = new Upload();
    upload.setReceiver(new Upload.Receiver() {
        @Override
        public OutputStream receiveUpload(String filename, String mimeType) {

            return baos; // Return the output stream to write to
        }
    });
    upload.addSucceededListener(new Upload.SucceededListener() {
        @Override
        public void uploadSucceeded(Upload.SucceededEvent succeededEvent) {
        System.out.println ( baos.toByteArray().toString());
    }
});

Note: there is some Vaadin-specific code which is related to their upload-component. The upload component should provide an OutPutStream, which is correct so far.

This is what `toString()` does for byte-arrays. Thats not whats _in_ the array. — tkausl, Oct 11 '16 at 10:49

score 1 · Accepted Answer · edited Apr 26 '22 at 12:23

1

Problem

[B@544641ab is the array type string ([B) combined with the identity hashcode of the byte array returned by baos.toByteArray(), not it's value.

Solution

Use Arrays.toString(baos.toByteArray()) instead of baos.toByteArray().toString(). You can also use baos.toString().

edited Apr 26 '22 at 12:23

Mark Rotteveel

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answered Oct 11 '16 at 10:49

Filipp Voronov

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Okay, I was not aware of this. Thank you for the answer. So .toByteArray() is doing its job like it is supposed to do I guess? I will mark the answer as soon as the website let's me do so – Tobias Kuess Oct 11 '16 at 10:53
@TobiasKuess, yes, you're right – Filipp Voronov Oct 11 '16 at 10:55
No it isn't. It is the result of `Object.toString()`, which concatenates the object type (`[B`) with `"@"` and the result of `System.identityHashCode()`. – user207421 Oct 11 '16 at 11:05
@EJP, no, for `ByteArrayOutputStream` the `toString()` is overridden and returns _ buffer's contents into a string decoding bytes using the platform's default character set_ as described [here](https://docs.oracle.com/javase/7/docs/api/java/io/ByteArrayOutputStream.html) – Filipp Voronov Oct 11 '16 at 11:10

score 1 · Answer 2 · answered Oct 11 '16 at 10:50

1

You are seeing the result of the default toString() of a byte[]. If you want to print it out properly, you could use Arrays.toString(byte[]):

System.out.println (Arrays.toString(baos.toByteArray());

answered Oct 11 '16 at 10:50

Mureinik

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ByteArrayOutPutSteam to Byte[] not working as expected

2 Answers2

Problem

Solution