Closing a ByteArrayOutputStream has no effect?

What does this statement, "Closing a ByteArrayOutputStream has no effect" (http://java.sun.com/javase/6/docs/api/java/io/ByteArrayOutputStream.html#close()) mean?

I want to make sure the memory in ByteArrayOutputStream gets released. Does ByteArrayOutputStream.close() really release the memory?

Thanks.

Solution 1:

Does ByteArrayOutputStream.close() really release the memory?

No. It does absolutely nothing. You can look at its source code:

public void close() throws IOException {
}

To release the memory, make sure there are no references to it and let the Garbage Collector do its thing. Just like with any other normal object.

File- and Socket-based streams are special because they use non-memory OS resources (file handles) that you can run out of independantly of memory. That's why closing them explicitly is important. But this does not apply to the purely memory-based ByteArrayOutputStream.