Android NullPointerException when accessing SQLite DB

Question

I need help guys! I have a bug which I've been working on for hours and can't solve.

I have a ListView and customadapter, listview is populated with objects from a local sqlite db. I have a button on each row of the listview which is supposed to delete the corresponding object from the database. However, when the button is clicked I query the database like so...

public Game getGame(gameid){    
    Long gameif = Long.parseLong(gameid);

            Game g = db.getGame(gameif);

    return g;   
}

The line Game g = db.getGame() is the one giving me the NPE. The incoming gameid is not null, the reference to the database db = new DatabaseHandler(this); isn't null (I don't think).

Here's the code from the DatabaseHandler:

Game getGame(Long id) {
    SQLiteDatabase db = this.getReadableDatabase();

    Game game= null;
    System.out.println(String.valueOf(id));
    Cursor cursor = db.query(TABLE_GAMES, new String[] { KEY_ID,
            KEY_PLAYERNAME, KEY_PLAYERNUMBER, KEY_LASTTURN, KEY_NEXTTURN }, KEY_ID + "= ?",
            new String[] { String.valueOf(id) }, null, null, null, null);

    if (cursor != null){
        cursor.moveToFirst();

    game = new Game(Long.parseLong(cursor.getString(0)), cursor.getString(1), 
            Integer.parseInt(cursor.getString(2)),
            cursor.getString(3), Integer.parseInt(cursor.getString(4)));
    }


    return game;
}

Thanks in advance!

Edit - Here's the logcat.

09-29 11:06:52.843: E/AndroidRuntime(16969): FATAL EXCEPTION: main
09-29 11:06:52.843: E/AndroidRuntime(16969): java.lang.NullPointerException
09-29 11:06:52.843: E/AndroidRuntime(16969):    at com.domsoft.ff.MainActivity.getGame(MainActivity.java:115)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at com.domsoft.ff.MainActivity.talkToAsync(MainActivity.java:71)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at com.domsoft.ff.GameCustomAdapter$1.onClick(GameCustomAdapter.java:72)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at android.view.View.performClick(View.java)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at android.view.View$PerformClick.run(View.java)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at android.os.Handler.handleCallback(Handler.java)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at android.os.Handler.dispatchMessage(Handler.java)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at android.os.Looper.loop(Looper.java)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at android.app.ActivityThread.main(ActivityThread.java)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at java.lang.reflect.Method.invokeNative(Native Method)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at java.lang.reflect.Method.invoke(Method.java)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java)
09-29 11:06:52.843: E/AndroidRuntime(16969):    at dalvik.system.NativeStart.main(Native Method)

Click on button handled in my customadapter then starts talktoasync() in the main activity, an asynctask is then run which sends some data to a server, then depending on the response code from the server, a record from the local db should be deleted. getGame() is triggered in the onPostExecute() of the asynctask.

Debug and check if your cursor is null, you do a not equal to null check, but then use the cursor in the next line — Ryan S
– Ryan S, Commented Sep 29, 2013 at 0:38
Please see the edit! Also thanks for your help, I'll start trying all the tips mentioned in this thread now. — dlee
– dlee, Commented Sep 29, 2013 at 10:14

Gilberto Ibarra · Accepted Answer · 2013-09-30 16:20:33Z

1

When you acces at the Data acces object, you first need have and instance of the object

-> db = new DatabaseHandler(this);

after you need open the database where you need to acces.

db.open() ;

Set this segment of code in your Handler:

private MySQLiteHelper dbHelper; 

   public void open() throws SQLException {

    db = dbHelper.getWritableDatabase();

    }

If you dont open the database Android throws NullPointerException . YOu have a problem when you opening the database and this throws the exeption.

You can see this tutorial for more information : http://www.vogella.com/articles/AndroidSQLite/article.html

edited Sep 30, 2013 at 16:20

answered Sep 29, 2013 at 4:46

Gilberto Ibarra

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