public DataSource(String URL, String username, String password) {
		try {
			Class.forName(DRIVERNAME);
			con = DriverManager.getConnection(URL, username, password);
			stmt = con.createStatement();
		} catch (SQLException e) {
			System.out.println("Cannot connect to database.");
			isConnected = false;
		} catch (ClassNotFoundException e) {
			System.out.println("Class is not found.");
			isConnected = false;
		}
	}