How to fix Cannot invoke connection is null error in mysql

Question

I found similar problems with this but haven't found a solution yet. I am making a create account form with a mysql connection but when I try to click the create button, I have this error.

Here is my code for myConnection

import java.sql.Connection;
import java.sql.DriverManager;

public class myConnection {
    
    public static Connection getConnection() {
        
        Connection con = null;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            con = DriverManager.getConnection("jdbc:mysql://localhost/javacontactsapp", "root", "");
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        }
        
        return con;
    }
}

Output when I changed it to ex.printStackTrace();

        Connection con = null;
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            con = DriverManager.getConnection("jdbc:mysql://localhost/javacontactsapp", "root", "");
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        
        return con;