sqlite predefined database null

Question

I'm a beginner in Sqlite, so sorry if I made some stupid mistakes :D

I got a NULL error in my predefined database :

NULL error

This error always happened when I start my App in the new computer/emulator, so I think it has something to do with my onCreate method. But, the onCreate should not needed because I use predefined database.

This is my database class :

private static String DATABASE_NAME = "ALGOLICIOUS_DB";
    private static int DATABASE_VERSION = 1;
    private static String TABLE_NAME = "msQuiz";
    private static String TABLE_HIGHSCORE = "msHighScore";

    private Context context;
    private SQLiteDatabase db;
    String queryCreate, queryUpdate, queryDelete, querySelect, queryInsert;
    Cursor cursor;

    public AlgoliciousDB(Context context) {
        this.context = context; 
        OpenHelper openHelper = new OpenHelper(this.context); 
        this.db = openHelper.getWritableDatabase(); 
    }

    public List<String> getQuestion(int chapter) {
        List<String> questionList = new ArrayList<String>();
        String result = "";
        querySelect = "SELECT * FROM " + TABLE_NAME + " WHERE question_chapter = " + chapter;

        try {
            cursor = this.db.rawQuery(querySelect, null);

            for(cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()){
                result += cursor.getString(1) + "%" + cursor.getString(2) + "%" + cursor.getString(3) + "%" + cursor.getString(4) + "%" + cursor.getString(5);
                questionList.add(result);
                result = "";
            }
            return questionList;

        } catch (Exception e) {
            return null;
        }
    }

    public int getHighScore(int chapter) {
        querySelect = "SELECT highscore FROM " + TABLE_HIGHSCORE + " WHERE highscore_id = " + chapter;
        int temp = 0;

        try {
            cursor = this.db.rawQuery(querySelect, null);

            for(cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()){
                temp = Integer.parseInt(cursor.getString(0));
            }
            return temp;

        } catch (Exception e) {
            return -1;
        }
    }

    public void Close() {
        db.close();
    }

    class OpenHelper extends SQLiteOpenHelper {
        public OpenHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
            onCreate(db);
        }
    }

Any help will be appreciated, thanks :D

when you catch an exception, log it, don't simply return a default value. that should help you pin down the issue — njzk2, Dec 03 '12 at 12:34
in onCreate, you are supposed to, like, create tables in your database — njzk2, Dec 03 '12 at 12:35
@njzk2 the problem is, i dont have any error/exception...my database file just vanished everytime i change the emulator/computer. Thanks :D — Blaze Tama, Dec 03 '12 at 14:08
@njzk2 i use the predefined database...so i shouldnt need to re-create the tables :D — Blaze Tama, Dec 03 '12 at 14:09
if you update it, you go in onUpgrade, which drops the table, in which case you'd need to create them again. Also, may be your database copy doesn't work. what do you use to import your DB ? — njzk2, Dec 03 '12 at 14:18
and still, please do print something when you catch an exception — njzk2, Dec 03 '12 at 14:18
you don't have any errors because your catch clause simply returns null. printStackTrace or something. — njzk2, Dec 03 '12 at 14:19
http://stackoverflow.com/questions/9109438/how-to-use-an-existing-database-with-an-android-application/9109728#9109728 — Yaqub Ahmad, Dec 03 '12 at 15:14
@YaqubAhmad please use that reference to answer my question, so i can accept that. Thanks :D — Blaze Tama, Dec 09 '12 at 14:11

score 1 · Accepted Answer · edited May 23 '17 at 12:12

1

Your answer is here: How to use an existing database with an Android application

Copy your database in Assets Folder and use the code provided in above link. Sample sample is also available you can try it.

edited May 23 '17 at 12:12

Community

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answered Dec 09 '12 at 14:48

Yaqub Ahmad

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sqlite predefined database null

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