Java array concatenation using a comma?

Question

I've got a bit of a puzzle I need help to unravel here and I've been unable to find the answer here thus far ITL.

In this file: https://bitcoinj.googlecode.com/git/core/src/main/java/com/google/bitcoin/core/PartialMerkleTree.java

Appears the line: byte[] left = recursiveExtractHashes(height-1, pos*2, used, matchedHashes).getBytes(), right;

Which eclipse seems to think is valid Java and it compiles just fine..

So what exactly does the ", right" portion perform?

I think its a declaration but I've never seen a declaration like this one.

Can anyone elaborate further?

SimplyPanda · Accepted Answer · 2015-03-05 22:13:01Z

7

This declaration is equivalent to something like this:

int i = 0, j;

right is declared but not initialized as an array of bytes, whereas left is both declared and initialized.

answered Mar 5, 2015 at 22:13

SimplyPanda

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5 Comments

RealSkeptic Over a year ago

Not instantiated, merely declared. Instantiation will be when new is called.

SimplyPanda Over a year ago

@RealSkeptic Right. Vocab is getting rusty, haven't done a programming interview in a while. Fixing... (Thanks!)

Akumaburn Over a year ago

Yes of course I see. I was distracted by the length and location of the assignment.

SimplyPanda Over a year ago

@Akumaburn Honestly, I think that code is poorly written for readability's sake. I would've left it as two separate lines. (Also, if you liked my answer, please accept it!) meta.stackexchange.com/questions/5234/…

yshavit Over a year ago

Agreed about the readibility. It's good to be able to identify it, but I wouldn't emulate it if I were you.

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