Java MySQL NullPointerException on query

Basically I have a problem with getting a ResultSet from a database. The errors occur around Line 34 (?) in this code block but I've marked it

ResultSet rs = caq.executeQuery("SELECT * FROM ProjectScore"); //error goes here

I get a null pointer exception on runtime and this is the output from the catch statement below:

null, calculating average score failed

java.lang.NullPointerException

[Ljava.lang.StackTraceElement;@1de2b1

The interesting thing is that I use the Connection Exactly the same in the class at the end and I receive no errors there. Copying the statement to the first class doesn't work either so I assume it's something else. I think that's all I have, any help is appreciated :)

import java.awt.*;
import java.awt.event.*;
import java.sql.*;

import javax.swing.*;

public class MainWindow extends JFrame implements ActionListener{
    //.......................
    private int [] averageScore;

    //References
    private LogInWindow liw;
    private NewUserWindow nuw;
    private ScoreWindow sw;
    private boolean isAnotherWindowOpen = false;
    private boolean isLoggedIn = false;
    private ConnectionAndQueries caq;

    public MainWindow(ConnectionAndQueries caq) throws SQLException{
        this.caq = caq;

        //.................................

        //Middle
        averageScore = new int [9];
        calculateAverageScore();
        setTable();

        //............................
    }

    private void calculateAverageScore() throws SQLException{
        try{
            ResultSet rs = caq.executeQuery("SELECT * FROM ProjectScore"); //error goes here
            int [] count = new int [9];
            int [] totalScore = new int [9];

            while(rs.next()){
                int itemID = rs.getInt("itemID");

                count[itemID]++;
                totalScore[itemID] += rs.getInt("Score");
            }

            for(int i = 0; i < 9; i++){
                averageScore[i] = totalScore[i] / count[i];
            }
        }
        catch (Exception e) {
            System.out.print(e.getMessage());
            System.out.println(", calculating average score failed");
            System.out.println(e.toString());
            System.out.println(e.getStackTrace().toString());
        }
    }
}




//next class

import java.sql.*;

public class ConnectionAndQueries {
    private static Connection connection;
    private static Statement statement;
    private MainWindow mw;

    public ConnectionAndQueries() throws ClassNotFoundException, SQLException{
        mw = new MainWindow(this);
        connect();
    }

    public static void connect() throws ClassNotFoundException, SQLException{
        try{
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection("jdbc:mysql://zzzzzzzzzz", "yyyy",     "xxxx"); //dont think im allowed to give that info
            statement = connection.createStatement();
        } catch (Exception e) {
            System.out.println("Connecting to the database failed");
        }
    }

    public ResultSet executeQuery(String query) throws SQLException {
        return statement.executeQuery(query);
    }

    public int executeUpdate(String update) throws SQLException {
          return statement.executeUpdate(update);
    }

    public static void main(String [] args) throws ClassNotFoundException, SQLException{
        ConnectionAndQueries caq = new ConnectionAndQueries();
    }
}




//another class which uses the connection class, and works.

import java.awt.*;
import java.awt.event.*;
import java.sql.*;

import javax.swing.*;

public class LogInWindow extends JFrame implements ActionListener{
    //........................

    //References
    private MainWindow mw;
    private ConnectionAndQueries caq;

    public LogInWindow(MainWindow mw, ConnectionAndQueries caq){
        this.mw = mw;
        this.caq = caq;

        //......................
    }

    public void actionPerformed(ActionEvent e) {
        if(e.getSource() == logIn){
            String usn = usernameField.getText();
            String pwd = passwordField.getText();

            try {
                ResultSet rs = caq.executeQuery("SELECT * FROM ProjectCustomer");

                while(rs.next()){
                    if(rs.getString("username").equals(usn)){
                        if(rs.getString("passwrd").equals(pwd)){
                            logInSuccess(usn);
                            mw.userLoggedIn(usn);
                            quit();
                        }
                    }
                }

                if(mw.isUserLoggedIn() == false)
                    logInFailed();

            } catch (Exception e2) {
                System.out.print(e2.getMessage());
                System.out.println(", error at log in");
                System.out.println(e2.toString());
            }
        }

        else if(e.getSource() == quit){
            quit();
        }
    }

    //............................
}