Question

please i am trying to make GPA calculator in java GUI but i the code isnt working so please anyone tell em what is the wrong with it and thanks in advance

import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.InputMismatchException;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.border.EmptyBorder;
public class GPA extends JFrame {
private JPanel contentPane;
private JTextField grades1;
private JTextField credits1;
private JTextField grades2;
private JTextField credits2;
private JTextField grades3;
private JTextField credits3;
private JTextField grades4;
private JTextField credits4;
private JTextField grades5;
private JTextField credits5;
private JLabel class6;
private JTextField grades6;
private JTextFiel