Ich habe versucht, eine SQLite-Datenbank zu erstellen und einige Dinge damit zu tun. Aber ich fand das meinonCreate Methode wird nicht einmal aufgerufen !!

Ich sende eine Nachricht an LogCat am Anfang desonCreate Methode.

Ich gehe davon aus, dass der (Super-) Konstruktor aufruftonCreate Methode. Ist das richtig?

Mein Code:

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

public class DatabaseHandler extends SQLiteOpenHelper {
    // Static Constants
    /*** Database details ***/
    // Database version
    private static final int DATABASE_VERSION           = 1;

    // Database name
    private static final String DATABASE_NAME           = "database_name";

    /*** Database Tables ***/
    /** Events **/
    // Event table
    private static final String TABLE_EVENT             = "event";

    // Event table columns
    private static final String COLUMN_EVENT_EID        = "_eid";

    private static final String COLUMN_EVENT_CREATION_DATE  = "creation_date";

    private static final String COLUMN_EVENT_TITLE      = "title";
    private static final String COLUMN_EVENT_ICON       = "icon";

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

    @Override
    public void onCreate(SQLiteDatabase db) {
        Log.e("MyApp", "onCreate invoked");
        // Tables creation queries
        String CREATE_EVENT_TABLE = "create table " + TABLE_EVENT + "(" + COLUMN_EVENT_EID + " integer primary key, "
                + COLUMN_EVENT_CREATION_DATE + " text, "
                + COLUMN_EVENT_TITLE + " text, "
                + COLUMN_EVENT_ICON + " text)";

        // Creating tables
        db.execSQL(CREATE_EVENT_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.e("MyApp", "onUpgrade invoked");
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_EVENT);
    }
}

Hauptaktivitätscode:

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        DatabaseHandler db = new DatabaseHandler(this);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}