How to represent an empty InputStream

Question

I'm reducing a stream of InputStreams like so:

InputStream total = input.collect(
    Collectors.reducing(
        empty,
        Item::getInputStream, 
        (is1, is2) -> new SequenceInputStream(is1, is2)));

For the identity InputStream, I'm using:

InputStream empty = new ByteArrayInputStream(new byte[0]);

This works, but is there a better way to represent an empty InputStream?

Answer 1

Since InputStream has only one abstract method, read(),

public abstract int read() throws IOException

Returns:
the next byte of data, or -1 if the end of the stream is reached.

it is easy to create an empty stream by an anonymous subclass. Like this:

InputStream empty = new InputStream() {
    @Override
    public int read() {
        return -1;  // end of stream
    }
};

But admittedly, it is more code than your empty ByteArrayInputStream.

Answer 2

Since Java 11, you could use a static method InputStream.nullInputStream():

Returns a new InputStream that reads no bytes. The returned stream is initially open. The stream is closed by calling the close() method. Subsequent calls to close() have no effect.