code: private void startThreads()
      {
          ReadingThread readingThread = new ReadingThread(this);
          WritingThread writingThread = new WritingThread(this);
  
          synchronized (mThreadsLock)
          {
              mReadingThread = readingThread;
              mWritingThread = writingThread;
          }
  
          // Execute onThreadCreated of the listeners.
          readingThread.callOnThreadCreated();
          writingThread.callOnThreadCreated();
  
          readingThread.start();
          writingThread.start();
      }
docs: Start both the reading thread and the writing thread.
  
  <p>
  The reading thread will call {@link #onReadingThreadStarted()}
  as its first step. Likewise, the writing thread will call
  {@link #onWritingThreadStarted()} as its first step. After
  both the threads have started, {@link #onThreadsStarted()} is
  called.
  </p>