Help in understanding GUI's!!!

Question

Hi everyone, I'm new to this type of forum, but I figured it can't hurt to ask for help wherever I can find it. I'm in a Java II class right now, and I'm having a hard time understanding how to build a GUI. I created the programs provided in the book, but I keep getting an error upon compiling, "unreachable statement". I have included my code, I'm not sure how to paste it properly, so I'm sorry if it's hard to read. Please let me know if anyone can help me out here. I'm not sure how much it matters, but the Java Machine we are using is 1.4.2... Thanks for any help!!!
**The first part is this: Rooms.java**
     Chapter 5:     Reserve a Party Room
     Programmer:     Sabrina M. Liberski
     Date:          December 16, 2007
     Filename:     Rooms.java
     Purpose:     This is an external class called by the Reservations.java program.
                    Its constructor method receives the number of nonsmoking and smoking rooms
                    and then creates an array of empty rooms.  The bookRoom() method accepts a
                    boolean value and returns a room number.
public class Rooms
     //declare class variables
     int numSmoking;
     int numNonSmoking;
     boolean occupied[];
     public Rooms(int non, int sm)
          //construct an array of boolean values equal to the total number of rooms
          occupied = new boolean[sm+non];
          for(int i=0; i<(sm+non); i++)
               occupied[i] = false; //set each occupied room to false or empty
          //initialize the number of smoking and nonsmoking rooms
          numSmoking = sm;
          numNonSmoking = non;
     public int bookRoom(boolean smoking)
          int begin, end, roomNumber=0;
          if(!smoking)
               begin = 0;
               end = numNonSmoking;
          else
               begin = numNonSmoking;
               end = numSmoking+numNonSmoking;
          for(int i=begin; i<end; i++)
               if(!occupied) //if room is not occupied
                    occupied[i] = true;
                    roomNumber = i+1;
                    i = end; //to exit loop
          return roomNumber;
}**The second part is:**  /*
     Chapter 5:     Reserve a Party Room
     Programmer:     Sabrina M. Liberski
     Date:          December 16, 2007
     Filename:     Reservations.java
     Purpose:     This program creates a windowed application to reserve a party room.
                    It calls an external class named Rooms.
import javax.swing.JOptionPane;
import java.awt.*;
import java.awt.event.*;
public class Reservations extends Frame implements ActionListener
     Color lightRed = new Color(255, 90, 90);
     Color lightGreen = new Color(140, 215, 40);
     Rooms room = new Rooms(5,3);
     Panel roomPanel = new Panel();
          TextArea roomDisplay[] = new TextArea[9];
     Panel buttonPanel = new Panel();
          Button bookButton = new Button("Book Room");
     Panel inputPanel = new Panel();
          Label custNameLabel = new Label("Name:");
          TextField nameField = new TextField(15);
          Label custPhoneLabel = new Label("Phone number:");
          TextField phoneField = new TextField(15);
          Label numLabel = new Label("Number in party:");
          Choice numberOfGuests = new Choice();
          CheckboxGroup options = new CheckboxGroup();
               Checkbox nonSmoking = new Checkbox("Nonsmoking", false, options);
               Checkbox smoking = new Checkbox("Smoking", false, options);
               Checkbox hidden = new Checkbox("", true, options);
     public Reservations()
          //set Layouts for frame and three panels
          this.setLayout(new BorderLayout());
               roomPanel.setLayout(new GridLayout(2,4,10,10));
               buttonPanel.setLayout(new FlowLayout());
               inputPanel.setLayout(new FlowLayout());
          //add components to room panel
          for (int i=1; 1<9; i++)
               roomDisplay[i] = new TextArea(null,3,5,3);
               if (i<6)
                    roomDisplay[i].setText("Room " + i + " Nonsmoking");
               else
                    roomDisplay[i].setText("Room " + i + " Smoking");
               roomDisplay[i].setEditable(false);
               roomDisplay[i].setBackground(lightGreen);
               roomPanel.add(roomDisplay[i]);
          //add components to button panel
          buttonPanel.add(bookButton);
          //add components to input panel
          inputPanel.add(custNameLabel);
          inputPanel.add(nameField);
          inputPanel.add(custPhoneLabel);
          inputPanel.add(phoneField);
          inputPanel.add(numLabel);
          inputPanel.add(numberOfGuests);
               for(int i = 8; i<=20; i++)
                    numberOfGuests.add(String.valueOf(i));
          inputPanel.add(nonSmoking);
          inputPanel.add(smoking);
          //add panels to frame
          add(buttonPanel, BorderLayout.SOUTH);
          add(inputPanel, BorderLayout.CENTER);
          add(inputPanel, BorderLayout.NORTH);
          bookButton.addActionListener(this);
          //overriding the windowClosing() method will allow the user to click the Close button
          addWindowListener(
               new WindowAdapter()
                    public void windowClosing(WindowEvent e)
                         System.exit(0);
     }//end of constructor method
     public static void main(String[] args)
          Reservations f = new Reservations();
          f.setBounds(200,200,600,300);
          f.setTitle("Reserve a Party Room");
          f.setVisible(true);
     } //end of main
     public void actionPerformed(ActionEvent e)
          if (hidden.getState())
               JOptionPane.showMessageDialog(null, "You must select Nonsmoking or Smoking.", "Error", JOptionPane.ERROR_MESSAGE);
          else
               int available = room.bookRoom(smoking.getState());
               if (available > 0) //room is available
                    roomDisplay[available].setBackground(lightRed); //display room as occupied
                    roomDisplay[available].setText(
                                                            roomDisplay[available].getText() +
                                                            "\n" +
                                                            nameField.getText() +
                                                            " " +
                                                            phoneField.getText() +
                                                            "\nparty of " +
                                                            numberOfGuests.getSelectedItem()
                                                       ); //display info in room
                    clearFields();
               else //room is not available
                    if (smoking.getState())
                         JOptionPane.showMessageDialog(null, "Smoking is full.", "Error", JOptionPane.INFORMATION_MESSAGE);
                    else
                         JOptionPane.showMessageDialog(null, "Nonsmoking is full.", "Error", JOptionPane.INFORMATION_MESSAGE);
                    hidden.setState(true);
               } //end of else block that checks the available room number
          } //end of else block that checks the state of the hidden option button
     } //end of actionPerformed method
     //reset the text fields and choice component
     void clearFields()
          nameField.setText("");
          phoneField.setText("");
          numberOfGuests.select(0);
          nameField.requestFocus();
          hidden.setState(true);
     } //end of clearFields() method
} //end of Reservations class                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

Answer 1

In order to display a component, that component has to be added to a container that is either that root container or has a parent container that is the root container. You have at least one JPanel, roomPanel, that is added to nothing. You will have to search through this to see if their are others.
But more importantly, you are coding this all wrong. You need to code like so:
1) create your class skeleton, see that it compiles and runs.
2) add enough to make a JFrame appear, nothing more. Make sure it compiles, runs, and you see the frame.
3) add code a little bit at a time, and after each addition, compile and run the code, make sure that you see any visual elements.
4) repeat section 3 until project done.
5) for larger projects, I create separate classes and run each one with its own main method to check it as I create it before adding it to the greater program.
If you don't do it this way, you will end up with a mess where when you correct one error, three more show up.
Also, I recommend that when an error or problem pops up like one did just now (invisible components) that you work on debugging it first for at least 1-2 hours before coming to the forum for answers. Otherwise you don't learn how to debug, an important skill to master.
Edited by: petes1234 on Dec 17, 2007 10:11 AM