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POAndroid MainActivity and BroadcastReceiver
 

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  1. POAndroid MainActivity and BroadcastReceiver
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    <p>I have a problem when trying to reach objects from different classes. I'm on an android project an I've done a socketconnection from my MainActivity class that extends Activity. Then I've made another class called SmsReceiver that extends BroadcastReceiver so I can get messages that are sent to my phone (emulator). Now I need the SmsReceiver class to use the outputstream object from the MainActivity class but I don't know how to reach it. I cannot make a new instance of MainActivity. </p> <p>Can I somehow send the outputstream object to the SmsReceiver class? I hope some of you got some tips, thanks in advance!</p> <hr> <p>Ok now I've gone for the interface solution but I'm stuck again!</p> <p>Here are my classes:</p> <p><strong>MainActivity:</strong></p> <pre><code>public class MainActivity extends Activity implements MainInterface { try { out = new PrintWriter(clientSocket.getOutputStream()); in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); } catch (IOException ex) { System.err.println("Error in creating Streams:" + ex.toString()); return; } public PrintWriter getOutputStream() { return out; } } </code></pre> <p><strong>MainInterface:</strong></p> <pre><code>public interface MainInterface { public PrintWriter getOutputStream(); } </code></pre> <p><strong>SmsReceiver:</strong></p> <pre><code>public class SmsReceiver extends BroadcastReceiver{ MainInterface mainInterface = new MainActivity(); ///// &lt;------ PrintWriter out; //// &lt;-------- @Override public void onReceive(Context context, Intent intent) { mainInterface.getOutputStream(); ////// &lt;------------ // Retrieves a map of extended data from the intent. final Bundle bundle = intent.getExtras(); try { if(bundle != null){ final Object[] pdusObj = (Object[]) bundle.get("pdus"); for(int i = 0; i &lt; pdusObj.length; i++){ SmsMessage currentMessage = SmsMessage.createFromPdu((byte[]) pdusObj[i]); String phoneNumber = currentMessage.getDisplayOriginatingAddress(); String senderNum = phoneNumber; String message = currentMessage.getDisplayMessageBody(); Log.i("SmsReceiver", "senderNum: "+ senderNum + "; message: " + message); out.println("senderNum: "+ senderNum + "; message: " + message); out.flush(); /// these two lines } } } catch (Exception e) { Log.e("SmsReceiver", "Exception smsReceiver" +e); } } } </code></pre> <p>For some reason the PrintWriter that I get through the interface is <em>null</em>, and the inputstream on the desktop (which is the program that should receive the message when doing <strong>out.println()</strong>) doesn't even get the message, it's just blocked at <strong>in.readLine()</strong>. Am I instantiating the interface the wrong way or what's going on?</p> <p>The logcat error print is: <strong>09-15 14:13:55.880: E/SmsReceiver(1361): Exception smsReceiverjava.lang.NullPointerException</strong></p>
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    1. COusually you would instantiate and register your Broadcast receiver in your activity.
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      1. POAndroid MainActivity and BroadcastReceiver
      1. USSu-Au Hwang
    2. COYou mean like not creating a separate class for the broadcastreceiver?
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    3. COyou can, but instantiate it in the Activity, e.g. MyBroadcastReceiver mReceiver = new MyBroadcastReceiver();
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      1. POAndroid MainActivity and BroadcastReceiver
      1. USSu-Au Hwang
 

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