public class Database {

private Connection          connection          = null;
private PreparedStatement   preparedStatement   = null;
private ResultSet           resultSet           = null;

// Method for registering a new account. Credentials are added into the database.
public void registerAccount(String username, String password, String ipAddress) {

    try {

        Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
        connection = DriverManager
                .getConnection("jdbc:derby:C:\DB;create=true;upgrade=true");
        String query = "INSERT INTO Users (username, password, ip_address) VALUES" + "(?,?,?)";
        preparedStatement = connection.prepareStatement(query);
        preparedStatement.setString(1, username);
        preparedStatement.setString(2, password);
        preparedStatement.setString(3, ipAddress);
        preparedStatement.executeUpdate();

    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        close();
    }

}

private void close() {

    try {

        if (resultSet != null) {
            resultSet.close();
        }
        if (preparedStatement != null) {
            preparedStatement.close();
        }
        if (connection != null) {
            connection.close();
        }
    } catch (Exception e) {
        e.printStackTrace();
    }

}

// Checks if credetials are correct.
public boolean checkLogin(String username, String password) {

    try {

        Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
        connection = DriverManager
                .getConnection("jdbc:derby:C:\DB;create=true;upgrade=true");
        String query = "SELECT username, password from Users WHERE username = ? AND password = ?";
        preparedStatement = connection.prepareStatement(query);
        preparedStatement.setString(1, username);
        preparedStatement.setString(2, password);
        resultSet = preparedStatement.executeQuery();

        if (resultSet.next()) {
            String user = resultSet.getString("username");
            String pass = resultSet.getString("password");
            if (username.equalsIgnoreCase(user)) {
                if (password.equals(pass)) {
                    return true;
                }
            }
        }

    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        close();
    }
    return false;
}