Can a ResultSet be 'null' in Java?

Question

I have a very basic bit of code which executes a select query and returns a boolean depending if the result set is empty or not.

public boolean checkIfUserHasPreferences(String username){
        ResultSet rs = null;
        boolean checkBoolean = false;

        try {
            DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
            con = DriverManager.getConnection(Messages.getString("OracleUserManagement.0"), Messages.getString("OracleUserManagement.1"), Messages.getString("OracleUserManagement.2")); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$

            PreparedStatement statement = con.prepareStatement("SELECT USERNAME FROM USER_PREFERENCES WHERE USERNAME = ?"); 
            statement.setString(1, username);
            rs = statement.executeQuery();
            if (rs == null){
                System.out.println("I checked it was true!");
                checkBoolean = true;
            } else {
                System.out.println("I checked it was false!");
                checkBoolean = false;
            }

            con.commit();

            con.close();

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

        return checkBoolean;
    }

What confuses is me that even though the table/database is empty, it always prints out "I checked it was false!".

Is this because even if a result set returns 0 rows, it does not = null? Should I be using while (rs.next()) to check instead?

Answer 1

You could have looked onto the API of Statement#executeQuery() method. It says:

Returns:

• a ResultSet object that contains the data produced by the given query; never null

Emphasis mine.

Should I be using while (rs.next()) to check instead?

Yes.