CODEWITHSUNDEEP
javaandroidsqlsqlite
Addev
Addev

Reputation: 32233

SQLiteOpenHelper and close method

I'm making some tests and every time I call to SQLiteOpenHelper.close() and then I try to reopen the database with, for example, SQLiteOpenHelper.getWritableDatabase() I get the exception java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteDatabase

Is there some way of reopen the database? or I should re-create the SQLiteOpenHelper object?

Here goes the code, it crashes the second time the method getNoteCount is called

public DBController(Context ctx) {
    this.mContext = ctx.getApplicationContext();
    mDbHelper = new OpenHelper(mContext);
}

public int getNoteCount(){
     SQLiteDatabase mDb =mDbHelper.getWritableDatabase();
     Cursor c= mDb.query("notes", null, null, null, null, null, null);
     int result=c.getCount();
     c.close();
     mDb.close();
     return result;
}



private static class OpenHelper extends SQLiteOpenHelper {

    DatabaseHelper(Context ctx) {
        super(ctx, DB_NAME, null, DB_VERSION);

    }
    ............
}

I'm considering to make something like this:

public abstract class DBHelper {

    private SQLiteOpenHelper openHelper;
    private int openCount = 0;

    protected abstract SQLiteOpenHelper newSQLiteOpenHelper();

    public void openDatabase() {
        open();
    }

    public void closeDatabase() {
        close();
    }

    protected synchronized SQLiteDatabase open() {
        if (openHelper == null) {
            openHelper = newSQLiteOpenHelper();
        }
        openCount++;
        return openHelper.getWritableDatabase();
    }

    protected synchronized void close() {
        openCount--;
        if (openCount == 0) {
            openHelper.close();
            openHelper = null;
        }

    }

}

and use it this way

public class DBController extends DBHelper{
    public  DBController(Context ctx) {
        this.mContext = ctx.getApplicationContext();
    }

    @Override
    protected SQLiteOpenHelper newSQLiteOpenHelper() {
        return new OpenHelper(mContext);
    }

    public int getNoteCount(){
         SQLiteDatabase mDb =open();
         Cursor c= mDb.query("notes", null, null, null, null, null, null);
         int result=c.getCount();
         c.close();
         close();
         return result;
    }
}

Upvotes: 2

Views: 3184

Answers (1)

Peter Birdsall
Peter Birdsall

Reputation: 3425

From what I've read, your not supposed to close the database until the application is destroyed. See Android error - close() was never explicitly called on database

Upvotes: 1

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