Help with a simple GUI.

Question

I am totally new to building GUI's. Everything I have picked up I did so online. From what I have learned this should work, but it throws all sorts of exceptions when I run it.
package com.shadowconcept.mcdougal;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class NavSystemGUI extends JApplet implements ActionListener
      String citylist[] = {"Birmingham", "Tuscaloosa", "Atlanta", "Montgomery", "Macon", "Mobile", "Tallahassee", "Ashburn", "Lake City", "Ocala", "Orlando", "Daytona Beach", "Jacksonville", "Savannah"};
      NavigationSystem N1 = new NavigationSystem();
   JLabel startposition = new JLabel("Starting Position");
   JLabel endposition = new JLabel("Ending Posiiton");
   JLabel choice = new JLabel("Make a Choice");
   JComboBox startselection = new JComboBox(citylist);
   JComboBox endselection = new JComboBox(citylist);
   ButtonGroup choices = new ButtonGroup();
   JRadioButton DFS = new JRadioButton("Depth-First Search");
   JRadioButton BFS = new JRadioButton("Breadth-First Search");
   JRadioButton shortestpath = new JRadioButton("Find the Shortest Path");
   JButton button = new JButton("Execute");
   String Start, End;
    public void init()
      Container con = getContentPane();
      con.setLayout(new FlowLayout());
      choices.add(DFS);
      DFS.setSelected(true);
      choices.add(BFS);
      choices.add(shortestpath);
      con.add(startposition);
      //startposition.setLocation(10, 20);
      con.add(startselection);
      //startselection.setLocation(50, 20);
      startselection.addActionListener(this);
      con.add(endposition);
      //endposition.setLocation(10, 40);
      con.add(endselection);
      //endselection.setLocation(50, 40);
      endselection.addActionListener(this);
      con.add(choice);
      //choice.setLocation(10, 60);
      con.add(DFS);
      DFS.addActionListener(this);
      con.add(BFS);
      BFS.addActionListener(this);
      con.add(shortestpath);
      shortestpath.addActionListener(this);
      con.add(button);
      button.addActionListener(this);
      startselection.requestFocus();
      Start = startselection.getName();
      End = endselection.getName();
    public void actionPerformed(ActionEvent e) {
        if(e.getSource() == button){
             if(DFS.isSelected()){
                  N1.DFS(Start, End);
             if(BFS.isSelected()){
                  N1.BFS(Start, End);
             if(shortestpath.isSelected()){
                  N1.shortestpath(Start, End);
}

Answer 1

rhm54 wrote:
I am totally new to building GUI's. Everything I have picked up I did so online. From what I have learned this should work, but it throws all sorts of exceptions when I run it.It compiles and runs fine for me. Perhaps your problems are with the NavigationSystem class? But I agree with Hunter: show your error messages and somehow indicate the lines in your code that cause the errors. I often find that reposting the code with comments indicating the offending lines works best. Good luck.