Method isEmpty

guava/src/com/google/common/io/ByteSource.java:151–165

Returns whether the source has zero bytes. The default implementation first checks {@link #sizeIfKnown}, returning true if it's known to be zero and false if it's known to be non-zero. If the size is not known, it falls back to opening a stream and checking for EOF. <p>Note that, in cases where {@c

()

   * @since 15.0
   */
  public boolean isEmpty() throws IOException {
    Optional<Long> sizeIfKnown = sizeIfKnown();
    if (sizeIfKnown.isPresent()) {
      return sizeIfKnown.get() == 0L;
    }
    Closer closer = Closer.create();
    try {
      InputStream in = closer.register(openStream());
      return in.read() == -1;
    } catch (Throwable e) {
      throw closer.rethrow(e);
    } finally {
      closer.close();
    }
  }

  /**
   * Returns the size of this source in bytes, if the size can be easily determined without actually