Byte array to string till '\n'

Question

I have Android <-> Arduino bluetooth communication. Sometimes Android gets two messages instead of one from Arduino. What i mean: if i send for ex. 5 bytes message "1234" from Arduino to Android over bluetooth, sometimes i get "1" 1 byte in one message and "234"+\n 4 bytes in second message. Sometimes i get full "1234"+\n 5 byte message and do not have any clue why. I need to split input message by delimiter and if i get separate message i get crash. So i need to append bytes to string till new line char comes.

How to add chars to string till "\n" new line char comes?

Case when data comes:

    case BLUETOOTH_RECEIVED:
        byte[] buffer = (byte[])msg.obj;
        int len = msg.arg1;
        if (len > 0 && buffer != null) {
            onBluetoothRead(buffer, len);
        }
        break;
    }

buffer to string:

private void onBluetoothRead(byte[] buffer, int len) {
    Log.i(LOGGER_TAG, String.format("Received: " +  output.replace("\n", "") + " message of " + "%d bytes", len));
    String output = new String(buffer, 0, len); // Add read buffer to new string
    m_deviceOutput.append(output); // Add (not replace) string to TextView
    StringTokenizer  splitStr = new StringTokenizer(output, ","); // split string by comma
    String numberOne = splitStr.nextToken(); // First split string
    String numberTwo = splitStr.nextToken(); // Second split string
    numberOne = numberOne.replaceAll("\\D+",""); // replace all chars, leave only numbers
    numberTwo = numberTwo.replaceAll("\\D+","");
}

LogCat:

07-22 14:06:15.099: I/DeviceActivity(20370): Received: 1234 message of 5 bytes
07-22 14:06:20.599: I/DeviceActivity(20370): Received: 1234 message of 5 bytes
07-22 14:06:27.349: I/DeviceActivity(20370): Received: 1 message of 1 bytes
07-22 14:06:27.469: I/DeviceActivity(20370): Received: 234 message of 4 bytes
07-22 14:06:37.219: I/DeviceActivity(20370): Received: 1 message of 1 bytes
07-22 14:06:37.349: I/DeviceActivity(20370): Received: 234 message of 4 bytes

in Arduino i can write like this and i want something similar here:

//Get data from RS485:
void READ01(){
  while (mySerial.available()){
    mySerial.read();
  }
    mySerial.println("01READ");
    momentas1="";
    delay(20);

    while (mySerial.available()) { 
      char c = mySerial.read();
      if (c == '\n'){
     break;
      }
      momentas1 += c; 
      }
}

This void READ01 adds chars to string until new line char comes.

Ruraj · Accepted Answer · 2014-07-24 06:48:55Z

2

You could use a buffer-like implementation by adding obtained string to another string until "\n" is received.

private String packet = "";
private void onBluetoothRead(byte[] buffer, int len) {
    Log.i(LOGGER_TAG, String.format("Received: " +  output.replace("\n", "") + " message of " + "%d bytes", len));
    String output = new String(buffer, 0, len); // Add read buffer to new string
    packet += output;
    if (packet.endsWith( "\n" ) {
        //do what you need to do
        m_deviceOutput.append(output); // Add (not replace) string to TextView
        StringTokenizer  splitStr = new StringTokenizer(packet, ","); // split string by comma
        String numberOne = splitStr.nextToken(); // First split string
        String numberTwo = splitStr.nextToken(); // Second split string
        numberOne = numberOne.replaceAll("\\D+",""); // replace all chars, leave only numbers
        numberTwo = numberTwo.replaceAll("\\D+","");
        packet = "";
    }

}

edited Jul 24, 2014 at 6:48

answered Jul 24, 2014 at 6:35

Ruraj

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5 Comments

Martynas Over a year ago

I didn't know string.endsWith()... I will try, but i believe 99.9% that this is an answer :)

Ruraj Over a year ago

hi there, I hope it works. But note that I have made an edit. There was a mistake in the code I wrote.

Martynas Over a year ago

At first when wrote code to Eclipse i corrected it :)

Martynas Over a year ago

Thank you Ruraj :) .startsWith() and .endsWith() are quite helpful :)

Ruraj Over a year ago

Glad to be of help :)

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