BaseEncoding.encodingStream().close() is non-idempotent

Closeable.close says:

If the stream is already closed then invoking this method has no effect.

Code:

StringWriter w = new StringWriter();
OutputStream out = BaseEncoding.base64().encodingStream(w);
out.write(0);
out.close();
System.out.println(w);
out.close();
System.out.println(w);

Output:

AA==
AA==A===

[swankjesse]

Being idempotent is useful; it’s very easy to double-close a stream due to ARM blocks and wrapping streams that close their underlying streams.

Synchronization is probably unnecessary. Java I/O streams are generally synchronized, but I’ve never seen anyone use multiple threads to concurrently read or write a shared stream.

[brettkail-wk]

It looks like the problem is just that close doesn’t adjust bitBufferLength. I don’t think thread-safety is required.