title: Number of bytes in byte array
body: <p>I have an array <code>byte[] arr</code>;</p>
  
  <pre><code>ByteArrayOutputStream out = new ByteArrayOutputStream();
  byte[] arr = out.toByteArray();
  </code></pre>
  
  <p>How can I measure the data size in arr (if it was written to disk or transferred via network)?
  Are below approaches are correct - they suppose that <code>sizeof(byte) = 1B</code></p>
  
  <pre><code>int byteCount = out.size();
  int byteMsgCount = arr.length;
  </code></pre>