Question

I have been slowing learning and building my first android app. I’m VERY new to java but have already done a couple of projects in C#, VB.NET (back in the day), Objective-C (have 6 apps in the store) and Fortran (waaaaaaaaaaaaaaaaaaaay back in the day 😉

So I just received from overseas a htc legend (I’m not in the US), which i bought in order to have a decent mid-level device for development (it’s running non-rooted adnroid 2.1)

The application I have been developing is target level 4 (android 1.6). It uses a 5 Mb sqlite3 database with a .mp3 extension to avoid compression within the apk and proper copying from assets to system folder.

It all works fine on the emulator, and on the device I see that the file size of the app after copying the database matches exactly what I see on the emulator.

now, on my main activity with a list view and a spinner, I bind some data through two array adapters. when running on the device all does smoothly. but when trying to run on the device this part of the code:

public class mainAct extends Activity implements OnItemSelectedListener, TextWatcher, OnItemClickListener
{   
        /** members */
        //private EditText searchtext;
        private ListView designations;
        private ArrayAdapter<String> adapterShapes;
        private ArrayAdapter<String> adapterTypes;
        private Spinner types;
      .  
      .  
      .    
    public void onCreate(Bundle savedInstanceState)   
    {  
      .  
      .  
      .    
        // DESIGNATIONS  
        // 
        adapterShapes = new ArrayAdapter<String>(this,R.layout.list_item,shapes);       // custom TextView Adapter  
        designations=(ListView)findViewById(R.id.designations);
        Log.e("MAIN.ACCT", "ok to 172");
        designations.setAdapter(adapterShapes);
        Log.e("MAIN.ACCT", "ok to 174");
        designations.setOnItemClickListener(this);

        // TYPES
        //
        adapterTypes=new ArrayAdapter<String>(this,R.layout.spinner_item,DT.get().typesInLibrary);
        types=(Spinner)findViewById(R.id.types);
        types.setAdapter(adapterTypes);
        types.setOnItemSelectedListener(this);
      .  
      .  
      .  
    }
}

Both designations.setAdapter(adapterShapes);
& types.setAdapter(adapterTypes);

give me a Null Pointer exception.

I’m using eclipse under mac, the LogCat window throws:

06-25 18:41:37.842:
ERROR/AndroidRuntime(9523): Uncaught
handler: thread main exiting due to
uncaught exception

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523):
java.lang.RuntimeException: Unable to
start activity
ComponentInfo{com.davidhomes.steel/com.davidhomes.steel.mainAct}:
java.lang.NullPointerException

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2596)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at

android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2621)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
android.app.ActivityThread.access$2200(ActivityThread.java:126)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1932)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
android.os.Handler.dispatchMessage(Handler.java:99)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
android.os.Looper.loop(Looper.java:123)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
android.app.ActivityThread.main(ActivityThread.java:4595)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
java.lang.reflect.Method.invokeNative(Native
Method)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
java.lang.reflect.Method.invoke(Method.java:521)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
dalvik.system.NativeStart.main(Native
Method)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): Caused by:
java.lang.NullPointerException

————————————————————– 06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
com.davidhomes.steel.mainAct.onCreate(mainAct.java:183)

————————————————————–

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2544)

06-25 18:41:37.891:
ERROR/AndroidRuntime(9523): … 11
more

06-25 18:46:38.252:
ERROR/ActivityManager(99): fail to set
top app changed!

Line 183 is the first setAdapter call (designations.setAdapter(adapterShapes);), when I comment it out the second setAdapter is the one breaking code

I’m a little lost here, the adapters show the proper number of items on the log window when running from the simulator and the device.

I admit to being a noob to both java and android, so any help is highly appreciated.

regards
david

Answer 1

Oops! it was my fault all along, somehow I had TWO layouts (one for different resolutions), the one being used on my device did not have the proper ListView and Spinner ID. That alternative layout was collapse into a folder and I just forgot about it (I had paused development of the app for about 2 month until I actually got a device to test on).

the one working fine was installing on the simulator but not on the device and vice-versa, weird as the good one matches the resolution of my device (I’m pretty sure I’m also missing something there but that’s not important right now)

Still, thanks Chris for pointing me to looking at the Null return value on findViewById. Being new to android I was lost as to were to begin

Best regards
david