Android ListActivity example using db4o

ListActivityWithDb4o.java

package org.example.events;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;

import com.db4o.Db4oEmbedded;
import com.db4o.ObjectContainer;
import com.db4o.ObjectSet;

import android.app.ListActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.widget.ArrayAdapter;

public class Events extends ListActivity {
	private final static String TAG = "EVENTS";

	private ObjectContainer db = null;
	private ArrayList<String> events = new ArrayList<String>();
	private ArrayAdapter<String> adapter;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		getEvents();

		adapter = new ArrayAdapter<String>(this,
				android.R.layout.simple_list_item_1, events);
		setListAdapter(adapter);

		addEvent("Hello, Android!");
	}

	@Override
	protected void onPause() {
		db().close();
		super.onPause();
	}

	@Override
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		Log.d(TAG, "key down!");
		addEvent("key down!");
		return super.onKeyDown(keyCode, event);
	}

	private ObjectContainer db() {
		try {
			if (db == null) {
				db = Db4oEmbedded.openFile(dbPath());
				Log.d(TAG, "opened new database connection");
			}

			return db;
		} catch (Exception e) {
			Log.e(TAG, "unable to open database");
			return null;
		}
	}

	private String dbPath() {
		return this.getDir("data", 0) + "/" + "events.db4o";
	}

	private void addEvent(String string) {
		SimpleDateFormat sdf = new SimpleDateFormat();
		Event event = new Event("[" + sdf.format(new Date()) + "] " + string);

		db().store(event);
		db().commit();

		events.add(event.toString());
		adapter.notifyDataSetChanged();
	}

	private void getEvents() {
		ObjectSet<Event> result = db().queryByExample(new Event(null));
		events.clear();

		while (result.hasNext()) {
			String event = result.next().toString();
			events.add(event);
		}

	}
}