This is the code for my trip planner,you need to figure out how to create a calculator function to enable users to calculate their own costs if they choose

// File: DropBoxTest.java

import javax.swing.*;
public class DropBoxTest extends JApplet
{  
   public DropBoxTest()
   {
       add(new DropBoxHelper());
   }  
  
   public static void main(String[] args)
   {
       JFrame frame = new JFrame();
       JApplet applet = new DropBoxTest();
       frame.add(applet);
       frame.setTitle("Drop Box Demo");
       frame.pack();
       frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
       frame.setVisible(true);
   }
}

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// File: DropBoxHelper.java
import java.awt.*;
import javax.swing.*;
public class DropBoxHelper extends JPanel
{
   private double COMPACT = 13;
   private double MID = 18;
   private double LUXURY = 15;
   private double SUV = 23;
   private double LEADED = 2.50;
   private double UNLEADED = 2.90;
   private double SUPER_UNLEADED = 3.00;
   private double DIESEL = 4.00;
  
   private String[] bLocations = {"AAA", "BBB", "CCC", "DDD", "EEE", "FFF"};
   private String[] eLocations = {"GGG", "HHH", "III", "JJJ", "KKK", "LLL"};
   private String[] vSizes = {"Compact", "Mid", "Luxury", "SUV"};
   private String[] gTypes = {"Leaded", "Unleaded", "Super Unleaded", "Diesel"};
  
   private JComboBox bl = new JComboBox(bLocations);
   private JComboBox el = new JComboBox(eLocations);
   private JComboBox vs = new JComboBox(vSizes);
   private JComboBox gt = new JComboBox(gTypes);
  
   private JLabel jlbl1 = new JLabel("Beginning Location: ");
   private JLabel jlbl2 = new JLabel("Ending Location: ");
   private JLabel jlbl3 = new JLabel("Vehicle Size: ");
   private JLabel jlbl4 = new JLabel("Gas Type: ");
   private JLabel jlbl5 = new JLabel("Enter total miles: ");
   private JLabel jlbl6 = new JLabel("Cost of gas per gallon: $");  
   private JLabel jlbl7 = new JLabel("Cost per mile: $");
   private JLabel jlbl8 = new JLabel("Total cost with oil change: $");
  
   JTextField jtf1 = new JTextField(5);
   JTextField jtf2 = new JTextField(5);
   JTextField jtf3 = new JTextField(5);
   JTextField jtf4 = new JTextField(5);
  
   JButton jbtn1 = new JButton("Submit");
   JButton jbtn2 = new JButton("Clear");
  
   private JPanel p1 = new JPanel();
   private JPanel p2 = new JPanel();
   private JPanel p3 = new JPanel();
   private JPanel p4 = new JPanel();
   private JPanel p5 = new JPanel();
   private JPanel p6 = new JPanel();
   private JPanel p7 = new JPanel();
   private JPanel p8 = new JPanel();
   private JPanel p9 = new JPanel();
  
   public DropBoxHelper()
   {
       setLayout(new GridLayout(9, 1));
      
       p1.add(jlbl1);
       p1.add(bl);
       p2.add(jlbl2);
       p2.add(el);
       p3.add(jlbl3);
       p3.add(vs);
       p4.add(jlbl4);
       p4.add(gt);
       p5.add(jlbl5);
       p5.add(jtf1);
       p6.add(jlbl6);
       p6.add(jtf2);
       p7.add(jbtn1);
       p7.add(jbtn2);
       p8.add(jlbl7);
       p8.add(jtf3);
       p9.add(jlbl8);
       p9.add(jtf4);
      
      
       add(p1);
       add(p2);
       add(p3);
       add(p4);
       add(p5);
       add(p6);
       add(p7);
       add(p8);
       add(p9);
   }
}