Merge java files into one and how to use keylistener or key bindings?

I have two questions. A. How do I merge my two .java files and B. how do I use keylistener or keybindings in my code ? I am open to either keylisteners or keybindings and have tried to do this, but I have not been sucessful.
I am using two files, which compile fine and run exactly as I have them coded. I am very new to Java, but have worked with HTML and Autohotkey extensivly, Autohotkey more than HTML. Any help would be appreciated.
RiskApp.java:

Code :

import javax.swing.*;
import java.text.NumberFormat;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.SwingUtilities;
import java.awt.*;
import java.awt.event.*;
 
public class RiskApp extends JFrame {
    private static void createAndShowGUI() {
        JFrame frame = new JFrame("Risk");
JPanel panel = new JPanel(new BorderLayout());
Container contentPane = frame.getContentPane();
contentPane.setLayout(new GridLayout(1,2));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Risk riskPanel = new Risk();
        frame.getContentPane().add(riskPanel);
        frame.setSize(305,90);
        frame.setResizable(false);
        frame.setVisible(true);
    }
 
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
} catch (UnsupportedLookAndFeelException e) {
} catch (ClassNotFoundException e) {
} catch (InstantiationException e) {
} catch (IllegalAccessException e) {
}
                createAndShowGUI();
            }
        });
    }
}

Risk.java

Code :

import javax.swing.*;
import java.awt.*;
import java.text.NumberFormat;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.*;
 
   public class Risk extends JPanel {
   public int leftNumber, rightNumber, setbad;
   public JButton Enter;
   public JFormattedTextField stupid, yummy;
   public JLabel smart, dumb, nook, shook;
   public String nos, yos, setnice;
   public NumberFormat yucker = NumberFormat.getNumberInstance();
   public NumberFormat nucker = NumberFormat.getNumberInstance();
 
   public Risk() {
      setbad = 1;
      smart = new JLabel("First Number:");
      add(smart);
	      stupid = new JFormattedTextField(yucker);
      stupid.setColumns(3);
      stupid.setText("0");
      add(stupid);
      boolean isDigit;
      dumb = new JLabel("Second Number:");
      add(dumb);
      yummy = new JFormattedTextField(nucker);
      yummy.setColumns(3);
      yummy.setText("0");
      add(yummy);
      Enter = new JButton("Enter");
      add(Enter);
      Enter.addActionListener(new ButtonListener());	
 
 
   }
   class ButtonListener implements ActionListener {
      ButtonListener() {
      }
 
      public final void actionPerformed(ActionEvent e) {
         if (e.getActionCommand().equals("Enter")) {
		if (setbad == 1) {
			shook = new JLabel("0");
			nook = new JLabel("0");
			add(shook);
			add(nook);
 
          	String nos = stupid.getText();
	  	String yos = yummy.getText();
	   	shook.setText("First Editable Number: " + nos);
	   	nook.setText("Second Editable Number: " + yos);
		setbad ++;
	revalidate();
}
else {
	  String nos = stupid.getText();
	  String yos = yummy.getText();
	   shook.setText("First Editable Number: " + nos);
	   nook.setText("Second Editable Number: " + yos);
	revalidate();
	}
 
 
 
         }
      }
   }
}

Thanks,
cc11rocks