Question

I am trying to connect to a terminal emulator using a library in android, this will connect to a serial device and should show me sent/received data. To attach to a terminal session I need to provide an inputstream to setTermIn(InputStream) and an outputstream to setTermOut(OutputStream).

However when I declare the streams as follows they default to null don’t they?

private OutputStream bos;
private InputStream bis;

...

//inside onCreate() method
session.setTermIn(bis);
session.setTermOut(bos);
/* Attach the TermSession to the EmulatorView. */
mEmulatorView.attachSession(session)

So when I try to attach my streams to the session i get an error:

FATAL EXCEPTION: TermSession input reader
java.lang.NullPointerException at jackpal.androidterm.emulatorview.TermSession$2.run(TermSession.java:137)

which points to this code in the library:

public void run()
{
    try
    {
        while (true)
        {
            int read = mTermIn.read(mBuffer);
            if (read == -1)
            {
                // EOF -- process exited
                return;
            }
            mByteQueue.write(mBuffer, 0, read);
            mMsgHandler.sendMessage(mMsgHandler.obtainMessage(NEW_INPUT));
        }
    }
    catch (IOException e)
    {
    }
    catch (InterruptedException e)
    {
    }
}

This is because I haven’t started sending and receiving data yet so I haven’t assigned the data to the streams. What do i do, set up some spurious data to assign to a stream?
I tried that and it complains still. Perhaps I am doing it wrong.

To send and receive data i have the following methods, although I shouldn’t be setting the stream every time I call them I imagine.

Overriding the method that sends data over serial to set up the stream, runs whenever I press enter:

public void sendData(byte[] data)
{
    bos = new ByteArrayOutputStream(data.length);
}

Runs whenever data is received:

public void onDataReceived(int id, byte[] data) 
{
    bis = new ByteArrayInputStream(data);
}

How do I initialize these correctly? And should I really be setting the stream every time I send and receive data, does it matter? Or should I do some check?

Answer 1

You must initialize bis and bos before using them

You can put it just before using these two line

session.setTermIn(bis);
session.setTermOut(bos);