How to solve delay in Inputstream.read() in android?

Question

I am working on a Bluetooth multiplayer game project.I followed the android Bluetooth overview https://developer.android.com/guide/topics/connectivity/bluetooth strictly.I used the following code to read and write data:-

public class MyBluetoothService {
private static final String TAG = "MY_APP_DEBUG_TAG";
private Handler handler; // handler that gets info from Bluetooth service

// Defines several constants used when transmitting messages between the
// service and the UI.
private interface MessageConstants {
    public static final int MESSAGE_READ = 0;
    public static final int MESSAGE_WRITE = 1;
    public static final int MESSAGE_TOAST = 2;

    // ... (Add other message types here as needed.)
}

private class ConnectedThread extends Thread {
    private final BluetoothSocket mmSocket;
    private final InputStream mmInStream;
    private final OutputStream mmOutStream;
    private byte[] mmBuffer; // mmBuffer store for the stream

    public ConnectedThread(BluetoothSocket socket) {
        mmSocket = socket;
        InputStream tmpIn = null;
        OutputStream tmpOut = null;

        // Get the input and output streams; using temp objects because
        // member streams are final.
        try {
            tmpIn = socket.getInputStream();
        } catch (IOException e) {
            Log.e(TAG, "Error occurred when creating input stream", e);
        }
        try {
            tmpOut = socket.getOutputStream();
        } catch (IOException e) {
            Log.e(TAG, "Error occurred when creating output stream", e);
        }

        mmInStream = tmpIn;
        mmOutStream = tmpOut;
    }

    public void run() {
        mmBuffer = new byte[1024];
        int numBytes; // bytes returned from read()

        // Keep listening to the InputStream until an exception occurs.
        while (true) {
            try {
                // Read from the InputStream.
                numBytes = mmInStream.read(mmBuffer);
                // Send the obtained bytes to the UI activity.
                Message readMsg = handler.obtainMessage(
                        MessageConstants.MESSAGE_READ, numBytes, -1,
                        mmBuffer);
                readMsg.sendToTarget();
            } catch (IOException e) {
                Log.d(TAG, "Input stream was disconnected", e);
                break;
            }
        }
    }

    // Call this from the main activity to send data to the remote device.
    public void write(byte[] bytes) {
        try {
            mmOutStream.write(bytes);

            // Share the sent message with the UI activity.
            Message writtenMsg = handler.obtainMessage(
                    MessageConstants.MESSAGE_WRITE, -1, -1, mmBuffer);
            writtenMsg.sendToTarget();
        } catch (IOException e) {
            Log.e(TAG, "Error occurred when sending data", e);

            // Send a failure message back to the activity.
            Message writeErrorMsg =
                    handler.obtainMessage(MessageConstants.MESSAGE_TOAST);
            Bundle bundle = new Bundle();
            bundle.putString("toast",
                    "Couldn't send data to the other device");
            writeErrorMsg.setData(bundle);
            handler.sendMessage(writeErrorMsg);
        }
    }

    // Call this method from the main activity to shut down the connection.
    public void cancel() {
        try {
            mmSocket.close();
        } catch (IOException e) {
            Log.e(TAG, "Could not close the connect socket", e);
        }
    }
 }
}

For writing data I am using the following code:-

String[] myString={"HI!","How Are YOU"};
mConnected.write(Arrays.toString(myString).getBytes());

But I see that inputstream.read() is receiving data quite late after another device is sending the data.I found some questions regarding this,but none of them seem to provide a satisfactory answer.Any suggestion will be highly helpful.

Answer 1

After

mmOutStream.write(bytes);

try to call:

mmOutStream.flush();

this will cause the bytes to be sent immediately.

https://docs.oracle.com/javase/7/docs/api/java/io/OutputStream.html#flush()