Question

I’ve found this code sample online, but I can’t get it to work. When it runs, the app crashes. Is there any easy solution for this?

public long getMaxID() {
        int id = 0;
        final String MY_QUERY = "SELECT MAX(_id) AS _id FROM db_table";
        Cursor mCursor = mDb.rawQuery(MY_QUERY, null);  

              if (mCursor.getCount() > 0) {
                mCursor.moveToFirst();
                id = mCursor.getInt(mCursor.getColumnIndex(MY_QUERY));
              }

    return id;
        }

My logcat error seems to be:

10-21 07:48:32.704: E/AndroidRuntime(4023): Caused by: java.lang.IllegalStateException: get field slot from row 0 col -1 failed

Answer 1

You cannot do getColumnIndex on some query string, you need to pass the column name which is _id. So instead of

 id = mCursor.getInt(mCursor.getColumnIndex(MY_QUERY));

Use

 id = mCursor.getInt(mCursor.getColumnIndex("_id"));