title: Java: Converting String to and from ByteBuffer and associated problems
body: <p>I am using Java NIO for my socket connections, and my protocol is text based, so I need to be able to convert Strings to ByteBuffers before writing them to the SocketChannel, and convert the incoming ByteBuffers back to Strings.  Currently, I am using this code:</p>
  
  <pre><code>public static Charset charset = Charset.forName("UTF-8");
  public static CharsetEncoder encoder = charset.newEncoder();
  public static CharsetDecoder decoder = charset.newDecoder();
  
  public static ByteBuffer str_to_bb(String msg){
    try{
      return encoder.encode(CharBuffer.wrap(msg));
    }catch(Exception e){e.printStackTrace();}
    return null;
  }
  
  public static String bb_to_str(ByteBuffer buffer){
    String data = "";
    try{
      int old_position = buffer.position();
      data = decoder.decode(buffer).toString();
      // reset buffer's position to its original so it is not altered:
      buffer.position(old_position);  
    }catch (Exception e){
      e.printStackTrace();
      return "";
    }
    return data;
  }
  </code></pre>
  
  <p>This works most of the time, but I question if this is the preferred (or simplest) way to do each direction of this conversion, or if there is another way to try.  Occasionally, and seemingly at random, calls to <code>encode()</code> and <code>decode()</code> will throw a 
  <code>java.lang.IllegalStateException: Current state = FLUSHED, new state = CODING_END</code> exception, or similar, even if I am using a new ByteBuffer object each time a conversion is done.  Do I need to synchronize these methods?  Any better way to convert between Strings and ByteBuffers?  Thanks!</p>