从SQLite rowID获取NullPointerException

Question

As the title says, I'm getting a NullPointerException and I have no idea why. I've been through the code several times and printed out the data to the logcat before it is entered and it looks fine. Before I enter the code I just want to let you know that I am using a RecyclerView if it wasn't obvious.

// Implement OnLongClick listener. Long Clicked items is removed from list.
@Override
public boolean onLongClick(View view) {
    ViewHolder holder = (ViewHolder) view.getTag();
    if (view.getId() == holder.mNameTextView.getId()) {

        mDataset.remove(holder.getPosition());

        Log.i("NULL POINTER", (holder.mNameTextView.getText().toString()));
        String temp = sqLiteDBadapter.getRowid(holder.mNameTextView.getText().toString()); // --- It fails on this line
        Long temp2 = Long.parseLong(temp);

        sqLiteDBadapter.deleteScore(temp2);

        // Call this method to refresh the list and display the "updated" list
        notifyDataSetChanged();

        Toast.makeText(sContext, "Item " + holder.mNameTextView.getText() + " has been removed from list",
                Toast.LENGTH_SHORT).show();

    }
    return false;
}

Here is part of the SQLiteDBadapter:

public String getRowid(String date) {
    mDbHelper = new DatabaseHelper(mCtx);
    SQLiteDatabase db=mDbHelper.getReadableDatabase();

    Cursor c = db.rawQuery("SELECT * from " + DATABASE_TABLE + " WHERE date = ?" , new String[] { date });
    if (c.moveToFirst()){
        long temp;
        temp = c.getLong(c.getColumnIndex(KEY_ROWID));
        rowID = String.valueOf(temp);
        Log.i("----_ROW ID = ", rowID);
    }else  if (!c.moveToFirst())
        Log.i("CURSOR ERROR", " CURSOR INDEX MOST LIKELY 0");
    else
        c.moveToFirst();

    return rowID;
}

I declare rowID as String rowID; ealier in the code

As you can see here: Database SQLite Fiddle the code for getting the row works perfectly fine.

Also the Log.i NULL POINTER prints the output right before it crashes: I/NULL POINTER﹕ Nov 2, 2014 11:51:14 AM and that is the correct format according to the Fiddle

11-02 12:29:30.917      419-419/com.archeryscoresmaterialdesign W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x4160f620)
11-02 12:29:30.927      419-419/com.archeryscoresmaterialdesign E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.archeryscoresmaterialdesign, PID: 419
java.lang.NullPointerException
        at com.archeryscoresmaterialdesign.RecyclerViewAdapter.onLongClick(RecyclerViewAdapter.java:90)
        at android.view.View.performLongClick(View.java:4476)
        at android.widget.TextView.performLongClick(TextView.java:8362)
        at android.view.View$CheckForLongPress.run(View.java:18451)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5171)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:837)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:653)
        at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
        at dalvik.system.NativeStart.main(Native Method)

Answer 1

Within this code

if (c.moveToFirst()){
    long temp;
    temp = c.getLong(c.getColumnIndex(KEY_ROWID));
    rowID = String.valueOf(temp);
    Log.i("----_ROW ID = ", rowID);
}else  if (!c.moveToFirst())
    Log.i("CURSOR ERROR", " CURSOR INDEX MOST LIKELY 0");
else
    c.moveToFirst();

you might end up never assigning anything to rowID and if you declared it simply String rowID; not String rowID = new String(); it stays null. Is this a possibility ?

Answer 2

Are you corectly creating sqLiteDBadapter?

I suppose you have created a subclass of SQLiteOpenHelper . You are trying to call method on Object, which is null. Try this:

SQLiteDBadapter db = new SQLiteDBadapter(ApplicationContext);

Now you should be able to call any methods on it. And after you are done with reading, writing, tec.. dont forget to close the DB connection.

db.close();