How can I return a ResultSet?

Question

I would like to ask for help.

I need the method to return results. But I get an exception: java.sql.SQLException: Operation not allowed after ResultSet closed

public class A implements AutoCloseable {

    protected Connection getConnection() {
        Connection connection = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection(url, user, password);
        } catch (SQLException | ClassNotFoundException e) {
            e.printStackTrace();
        }
        return connection;
    }

    public ResultSet GetResultSet() {

        ResultSet resultSet = null;

        try (Connection connection = getConnection()) {

            Statement statement = connection.createStatement();

            if (statement.execute(SELECT_ALL_USERS)) {
                resultSet = statement.getResultSet();
            }

        } catch (SQLException e) {
            e.printStackTrace();
        }

        return resultSet;
    }

    @Override
    public void close() throws SQLException {

    }
}

I don't know what to do. Where is the problem? Do you give me any hint of which way ?

Your help would be greatly appreciated.

Maybe I should override the next() method from the ResultSet interface. But I don't know how to do it.

Answer 1

You use the try-with-resources statement to get the connection:

try (Connection connection = getConnection()) {

The whole point of that statement is to close the connection at the end. And closing the connection also closes its statements and result sets.

Don't return a ResultSet. Return a List of objects.

And please, respect the Java naming conventions, too.