DatabaseManager.java

package com.nonomartinez.app.managers;

import java.util.concurrent.atomic.AtomicInteger;

import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

/**
 * Database Manager
 * 
 * @author nonom
 */
public class DatabaseManager
{

	private final AtomicInteger _counter = new AtomicInteger();

	private static DatabaseManager _instance;
	private static SQLiteOpenHelper _helper;
	private SQLiteDatabase _db;

	public static synchronized void initialize(SQLiteOpenHelper helper)
	{
		if (_instance == null) {
			_instance = new DatabaseManager();
			_helper = helper;
		}
	}

	public static synchronized DatabaseManager getInstance()
	{
		if (_instance == null) {
			throw new IllegalStateException(DatabaseManager.class.getSimpleName() + " initialize() first.");
		}

		return _instance;
	}

	public synchronized SQLiteDatabase openDatabase()
	{
		if (_counter.incrementAndGet() == 1) {
			_db = _helper.getWritableDatabase();
		}
		return _db;
	}

	public synchronized void closeDatabase()
	{
		if (_counter.decrementAndGet() == 0) {
			_db.close();
		}
	}
}