sdcard上数据库的游标未关闭或无效

在下面的代码中，在sdcard上连接数据库，数据库打开但在logcat中显示错误 .

package com.avizhegroup.islamatlas.SQLiteMethods;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

import com.avizhegroup.islamatlas.model.Point;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Environment;
import android.util.Log;

public class DatabaseHandler extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "Data.db";

    private static final String TABLE_POINTDATA = "PointData";
    private static final String TABLE_POINTDATA_PRIMARYCATEGORYID = "PrimaryCategoryId";
    private static final String TABLE_POINTDATA_SECONDARYCATEGORYID = "SecondaryCategoryId";
    private static final String TABLE_POINTDATA_POINTID = "PointId";
    private static final String TABLE_POINTDATA_POINTNAME = "PointName";
    private static final String TABLE_POINTDATA_POINTSUMMARY = "PointSummary";
    private static final String TABLE_POINTDATA_POINTLAT = "PointLat";
    private static final String TABLE_POINTDATA_POINTLNG = "PointLng";
    private static final String TABLE_POINTDATA_POINTMARKERKIND = "PointMarkerKind";
    private static final String TABLE_POINTDATA_TAG = "POINT DATA TAG";

    private SQLiteDatabase db;

    public DatabaseHandler(Context context) {
        super(context, DATABASE_NAME, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }

    // Getting All Points
    public List getAllPoints() {
        List pointsList = new ArrayList();

        String selectQuery = "SELECT * FROM " + TABLE_POINTDATA;
        File dbfile = new File(Environment.getExternalStorageDirectory()
                .getPath() + File.separator + "Data.db");
        db = SQLiteDatabase.openOrCreateDatabase(dbfile, null);

        if (db.isOpen()) {
            Log.d("ISLAM ATLAS", "database is Open");
        }

        Cursor cursor = db.rawQuery(selectQuery, null);
        try {
            if (cursor.moveToFirst()) {
                do {
                    Point point = new Point();
                    point.setPrimaryCategoryId(Integer.parseInt(cursor
                            .getString(0)));
                    point.setSecondaryCategoryId(Integer.parseInt(cursor
                            .getString(1)));
                    point.setId(Integer.parseInt(cursor.getString(2)));
                    point.setName(cursor.getString(3));
                    point.setSummary(cursor.getString(4));
                    point.setLatitude(Double.parseDouble(cursor.getString(5)));
                    point.setLongtitude(Double.parseDouble(cursor.getString(6)));
                    point.setType(cursor.getString(7));

                    pointsList.add(point);

                } while (cursor.moveToFirst());
            }
        } finally {
            cursor.deactivate();
            cursor.close();
            db.close();
        }
        return pointsList;
    }
}

和logcat错误是：

10-20 10:31:33.069: E/Database(460): close() was never explicitly called on database '/mnt/sdcard/Data.db' 
10-20 10:31:33.069: E/Database(460): android.database.sqlite.DatabaseObjectNotClosedException: Application did not close the cursor or database object that was opened here
10-20 10:31:33.069: E/Database(460):    at android.database.sqlite.SQLiteDatabase.(SQLiteDatabase.java:1810)
10-20 10:31:33.069: E/Database(460):    at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:817)
10-20 10:31:33.069: E/Database(460):    at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:851)
10-20 10:31:33.069: E/Database(460):    at android.database.sqlite.SQLiteDatabase.openOrCreateDatabase(SQLiteDatabase.java:844)
10-20 10:31:33.069: E/Database(460):    at com.avizhegroup.islamatlas.SQLiteMethods.DatabaseHandler.getAllPoints(DatabaseHandler.java:51)
10-20 10:31:33.069: E/Database(460):    at com.avizhegroup.islamatlas.MainActivity.onCreate(MainActivity.java:40)
10-20 10:31:33.069: E/Database(460):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)

谢谢你的帮助 .