Msgstr "There is no default constructor available in android.database.sqlite.SQLitepenhelper" in Android Studio

Question

An attempt to extend the class using SQLiteOpenHelper, but this error appears: "There is no default constructor available in android.database.sqlite.SQLitepenhelper" together with the other "cannot resolve the symbol Category, Note, ..."

class DbHelper extends SQLiteOpenHelper { @Override public void onCreate(SQLiteDatabase db) { db.execSQL(Category.getSql()); db.execSQL(Note.getSql()); db.execSQL(Attachment.getSql()); db.execSQL(CheckItem.getSql()); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS " + Category.TABLE_NAME); db.execSQL("DROP TABLE IF EXISTS " + Note.TABLE_NAME); db.execSQL("DROP TABLE IF EXISTS " + Attachment.TABLE_NAME); db.execSQL("DROP TABLE IF EXISTS " + CheckItem.TABLE_NAME); onCreate(db); } 

Answer 1

You need to define an explicit constructor yourself that calls the 4- or 5-arg super SQLiteOpenHelper in SQLiteOpenHelper .

For example:

 public DbHelper(Context context) { super(context, "database.db", null, 1); } 

where database.db is the name of your database and 1 is the version.

Answer 2

If your DBHelper child, then this post will help, othervise, you can understand everything. First define it, like this one, outside of your class, means uperside ...

 private DBHelper ourHelper; private final Context ourContext; 

Then use this

 class DbHelper extends SQLiteOpenHelper { public DBHelper(Context context) { super(context, DB_NAME, null, DB_VIRSION); // TODO Auto-generated constructor stub } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(Category.getSql()); db.execSQL(Note.getSql()); db.execSQL(Attachment.getSql()); db.execSQL(CheckItem.getSql()); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS " + Category.TABLE_NAME); db.execSQL("DROP TABLE IF EXISTS " + Note.TABLE_NAME); db.execSQL("DROP TABLE IF EXISTS " + Attachment.TABLE_NAME); db.execSQL("DROP TABLE IF EXISTS " + CheckItem.TABLE_NAME); onCreate(db); } 

And then try this context for the parent class

 public MyDatabase(Context c){ ourContext=c; }