SQLite connection object leaked - Android

问题

I am making my first android app, and I took some sqlite tutorials first, that taught me to use a databaseHelper that extends SQLiteOpenHelper. So my databaseHelper does extend SQLiteOpenHelper. I get a sqlite connection leak warning in the Logcat so would like some advice about what to do to fix that.

I get this error:

02-01 21:39:50.740: W/SQLiteConnectionPool(32061): A SQLiteConnection object for database '/data/data/com.btf271.fashionassistant/databases/clothingManager' was leaked!  Please fix your application to end transactions in progress properly and to close the database when it is no longer needed.

My databaseHelper functions that are called where the leak occurs:

 public List<Sticker> getObjectsByGenderAndCategory(String gender, String category) {
        List<Sticker> objects = new ArrayList<Object>();
        String selectQuery = String.format(
                "SELECT * FROM %s WHERE %s = \"%s\" AND %s = \"%s\"",
                TABLE_OBJECT, KEY_GENDER, gender, KEY_CATEGORY, category);

        Log.e(LOG, selectQuery);

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor c = db.rawQuery(selectQuery, null);
     try{
        // looping through all rows and adding to list
        if (c.moveToFirst()) {
            do {
                Object o = createClothingItemJavaObject(c);

                // adding to object list
                objects.add(o);
            } while (c.moveToNext());
        }
     }finally {
           c.close();
db.close();
     }
        return objects;
    }

I found this which I will try tomorrow. It's late.

Thanks.

回答1:

All I did was implement this answer to a similar question and now it doesn't show the SQL connection object leak error. I cannot recommend this enough. It only took a few minutes to implement and worked.

Here is the code:

public class DatabaseHelper extends SQLiteOpenHelper { 

  private static DatabaseHelper mInstance = null;

  private static final String DATABASE_NAME = "database_name";
  private static final String DATABASE_TABLE = "table_name";
  private static final int DATABASE_VERSION = 1;

  public static DatabaseHelper getInstance(Context ctx) {

    // Use the application context, which will ensure that you 
    // don't accidentally leak an Activity's context.
    // See this article for more information: http://bit.ly/6LRzfx
    if (mInstance == null) {
      mInstance = new DatabaseHelper(ctx.getApplicationContext());
    }
    return mInstance;
  }

  /**
   * Constructor should be private to prevent direct instantiation.
   * make call to static factory method "getInstance()" instead.
   */
  private DatabaseHelper(Context ctx) {
    super(ctx, DATABASE_NAME, null, DATABASE_VERSION);
  }
}

回答2:

I fixed this by adding

@Override
protected void finalize() throws Throwable {
    this.close();
    super.finalize();
}

to my SQLiteOpenHelper extended class

回答3:

Match each call to getReadableDatabase() and getWritableDatabase() to a corresponding close() on the same database object.

For example, your getAllClothingItemsByGenderAndCategory() calls getReadableDatabase() but does not close() it. Add db.close() after c.close().

Your closeDB() makes no sense since it gets a new reference to the database with getReadableDatabase() and closes just that. It does nothing to close any existing database connection.

回答4:

Each time you open a database(readable or writable) and cursor which uses memory resources has to be deallocated by using ".close();" after its usage ends in each database function.. by your_database object.close(); and cursor object.close();

来源：https://stackoverflow.com/questions/21496221/sqlite-connection-object-leaked-android

标签

android

sqlite

memory-leaks

sqliteopenhelper