我正在尝试使用sqlite
在Android手机上创建本地数据库。
我有一个辅助类,如下所示,用于创建数据库并提供“帮助”。
我想在代码的主要部分创建该类的对象,并在那里创建数据库和表。
问题:
每当我创建该类的一个对象时,似乎没有调用辅助类中的onCreate
方法。我认为应该会发生这种情况,我认为onCreate
基本上是该类的构造函数。(我相信我错了)
- 那么,为什么它不调用
onCreate
方法? - 或者我如何让它在我创建该类的对象处创建数据库和表?
- 如果这不是一个好方法,有什么更好的方法可以做到这一点?
public class SmartDBHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "smart_lite_db.db";
private static final int DATABASE_VERSION = 2;
private static final String NOTIFY_TABLE_NAME = "user_notify_data";
private static final String HR_TABLE_NAME = "user_hr_data";
private static final String NOTIFY_TABLE_CREATE =
"CREATE TABLE " + NOTIFY_TABLE_NAME +
" (counter INTEGER PRIMARY KEY, " +
"userresponse INTEGER, " +
"notifytime INTEGER);";
private static final String DATA_TABLE_CREATE =
"CREATE TABLE " + HR_TABLE_NAME +
" (counter INTEGER PRIMARY KEY, " +
"hr INTEGER, " +
"act INTEGER, " +
"timestamp INTEGER);";
public SmartDBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
// TODO Auto-generated constructor stub
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
Log.v("smartdbhelper", "before creation");
db.execSQL(NOTIFY_TABLE_CREATE);
Log.v("smartdbhelper", "middle creation");
db.execSQL(DATA_TABLE_CREATE);
Log.v("smartdbhelper", "after creation");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
}
public class SmartApp extends Activity implements OnSharedPreferenceChangeListener {
private SmartDBHelper dBHelper;
public void onCreate(Bundle savedInstanceState) {
//where i am wanting to create the database and tables
dBHelper = new SmartDBHelper(getContext());
}
}