can't find the mistake with the app in android

Question

hi,for long i am trying to develop an app which would inform the user of any incoming message via speech, i have three classes, TextSpeaker, Receiver and SpeakerService. When i start the app and click on Start button, i get runtime error:

06-21 13:54:36.088: ERROR/AndroidRuntime(528): Uncaught handler: thread main exiting due to uncaught exception
06-21 13:54:36.119: ERROR/AndroidRuntime(528): java.lang.RuntimeException: Unable to     start service com.example.TextSpeaker.SpeakerService@43bb2ff8 with Intent {  cmp=com.example.TextSpeaker/.SpeakerService }: java.lang.NullPointerException
06-21 13:54:36.119: ERROR/AndroidRuntime(528):     at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2882)
....

06-21 13:54:36.119: ERROR/AndroidRuntime(528): Caused by: java.lang.NullPointerException
06-21 13:54:36.119: ERROR/AndroidRuntime(528):     at  com.example.TextSpeaker.SpeakerService.onStart(SpeakerService.java:33)
06-21 13:54:36.119: ERROR/AndroidRuntime(528):     at android.app.Service.onStartCommand(Service.java:306)
06-21 13:54:36.119: ERROR/AndroidRuntime(528):     at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2873)
06-21 13:54:36.119: ERROR/AndroidRuntime(528):     ... 10 more

Here are my 3 classes: TEXTSPEAKER CLASS:

package com.example.TextSpeaker;

import java.util.Locale;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.speech.tts.TextToSpeech;
import android.speech.tts.TextToSpeech.OnInitListener;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

// the following programme converts the text to speech 

public class TextSpeaker extends Activity  implements OnInitListener {
/** Called when the activity is first created. */
int MY_DATA_CHECK_CODE = 0;
public TextToSpeech mtts;
public Button button,stop_button;
//public EditText edittext;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    button = (Button)findViewById(R.id.button);
    stop_button=(Button)findViewById(R.id.stop_button);

    Intent myintent = new Intent();
    myintent.setAction(TextToSpeech.Engine.ACTION_CHECK_TTS_DATA);
    startActivityForResult(myintent, MY_DATA_CHECK_CODE);
    //edit text=(EditText)findViewById(R.id.edittext);
}

    public void buttonClickListener(View src){
        switch(src.getId())
        {
        case(R.id.button):
            Toast.makeText(getApplicationContext(), "The service has been started\n Every new message will now be read out", Toast.LENGTH_LONG).show();
             startService(new Intent(this,SpeakerService.class));
             break;
        case(R.id.stop_button):
            Toast.makeText(getApplicationContext(), "The service has been stopped\n ", Toast.LENGTH_LONG).show();
            stopService(new Intent(this,SpeakerService.class));
            break;
        }
    }



    protected void onActivityResult(int requestcode,int resultcode,Intent data)
    {
        if(requestcode == MY_DATA_CHECK_CODE)
        {
            if(resultcode==TextToSpeech.Engine.CHECK_VOICE_DATA_PASS)
            {
                // success so create the TTS engine
                mtts = new TextToSpeech(this,this);
                mtts.setLanguage(Locale.ENGLISH);

            }
            else
            {
                //install the Engine
                Intent install = new Intent();
                install.setAction(TextToSpeech.Engine.ACTION_INSTALL_TTS_DATA);
                startActivity(install);
            }
        }

    }
    public void onDestroy(Bundle savedInstanceStatBundle)
    { 
        mtts.shutdown();
    }

    //public void onPause()
    //{ 
    //  super.onPause();
    //  // if our app has no focus
    //  if(mtts!=null)
    //   mtts.stop();
   // }
    @Override
    public void onInit(int status) {
        if(status==TextToSpeech.SUCCESS)
            button.setEnabled(true);

    }


}

RECEIVER CLASS:

package com.example.TextSpeaker;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent; 
import android.os.Bundle;
import android.telephony.SmsMessage; // supports both gsm and cdma
import android.util.Log;
import android.widget.Toast;



public class Receiver extends BroadcastReceiver{

//TextSpeaker tsp=new TextSpeaker();

public String str="";
@Override
public void onReceive(Context context, Intent intent) {
    Bundle bundle = intent.getExtras();
    Log.d("Receiver","Message received successfully");

    SmsMessage[] msgs = null;

    if(bundle!=null)
    {
        // retrive the sms received

        Object[] pdus = (Object[])bundle.get("pdus");
        msgs = new SmsMessage[pdus.length];
        for(int i=0;i<msgs.length;i++)
        {
            msgs[i]=SmsMessage.createFromPdu((byte[]) pdus[i]);
            str+="Message From "+msgs[i].getOriginatingAddress()+".";
            str+="The message is "+msgs[i].getMessageBody().toString();
        }
        Toast.makeText(context,str,Toast.LENGTH_SHORT).show();


    }



}

}

SERVICESPEAKER CLASS:

package com.example.TextSpeaker;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.speech.tts.TextToSpeech;
import android.util.Log;
import android.widget.Toast;


public class SpeakerService extends Service {

Receiver rv = new Receiver();
TextSpeaker tspker = new TextSpeaker();
//public TextToSpeech mtts;
@Override
public IBinder onBind(Intent arg0) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void onCreate(){
    //mtts =new TextToSpeech(getBaseContext(), null);
    Log.d("SpeakerService","Service created successfully!");
    //mtts.speak(rv.str, TextToSpeech.QUEUE_FLUSH,null);

}
@Override
public void onStart(Intent intent,int startid)
{
    Log.d("SpeakerService","Service started successfully!");
    tspker.mtts.speak(rv.str, TextToSpeech.QUEUE_FLUSH,null);
}
@Override
public void onDestroy(){
    if(tspker.mtts!=null)
    {
        tspker.mtts.stop();
        Toast.makeText(getApplicationContext(),"The service has been destroyed!", Toast.LENGTH_SHORT).show();
    }

}

}

Answer 1

looks like tspker.mtts is NULL.

add some logging in SpeakerService.onStart, to check that, or other NULL cases:

public void onStart(Intent intent,int startid)
{
    Log.d("SpeakerService","Service started successfully!");
    Log.d("SpeakerService","rv = " + rv.toString());
    Log.d("SpeakerService","tspker = " + tspker.toString());
    Log.d("SpeakerService","tspker.mtts = " + tspker.mtts.toString());
    tspker.mtts.speak(rv.str, TextToSpeech.QUEUE_FLUSH,null);
}