Thread: Why is my JFrame not showing components such as JComboBoxes

HI, I would really appreciate it if someone could look through my code and find out (what i can't) why and where my code is going wrong, Problem is my JFrame is not showing anything, point me in the right direction please thanks (Perhaps test it in your own IDE on your own PCs/laptop)

// Project: RestaurantBillCalculator.java Calculates a table's bill.
 
// Import statements for different classes
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JComponent;
import java.sql.Connection;
import java.sql.Statement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.awt.Container;
import javax.swing.BorderFactory;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.ResultSetMetaData;
import java.sql.ResultSet;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JOptionPane;
 
 
 
 
public class RestaurantBillCalculator extends JFrame
{
   static final String DATABASE_URL = "jdbc:mysql://localhost/restaurant";
   static final String DATABASE_USERNAME = "root";
   static final String DATABASE_PASSWORD = "password"; 
 
   // JLabel for Restaurant
   private JLabel restaurantJLabel;
 
   // JPanel to display waiter information
   private JPanel waiterJPanel;
 
   // JLabel and JTextField for table number
   private JLabel tableNumberJLabel;
   private JTextField tableNumberJTextField;
 
   // JLabel and JTextField for waiter name
   private JLabel waiterNameJLabel;
   private JTextField waiterNameJTextField;
 
   // JPanel to display menu items
   private JPanel menuItemsJPanel;
 
   // JLabel and JComboBox for beverage
   private JLabel beverageJLabel;
   private JComboBox beverageJComboBox;
 
   // JLabel and JComboBox for appetizer
   private JLabel appetizerJLabel;
   private JComboBox appetizerJComboBox;
 
   // JLabel and JComboBox for main course
   private JLabel mainCourseJLabel;
   private JComboBox mainCourseJComboBox;
 
   // JLabel and JComboBox for dessert
   private JLabel dessertJLabel;
   private JComboBox dessertJComboBox;
 
   // JButton for calculate bill
   private JButton calculateBillJButton;
 
   // JLabel and JTextField for subtotal
   private JLabel subtotalJLabel;
   private JTextField subtotalJTextField;
 
   // JLabel and JTextField for tax
   private JLabel taxJLabel;
   private JTextField taxJTextField;
 
   // JLabel and JTextField for total
   private JLabel totalJLabel;
   private JTextField totalJTextField;
 
   // constant for tax rate
   private final static double TAX_RATE = 0.05;
 
   // declare instance variables for database processing
   private Connection myConnection;
   private Statement myStatement;
   private ResultSet myResultSet;
 
   // declare instance variable ArrayList to hold bill items
    private ArrayList billItems = new ArrayList();
 
    // Constructor
   public RestaurantBillCalculator( String databaseUserName, String databasePassword )
   {
     try 
     {
         myConnection = DriverManager.getConnection
        (DATABASE_URL, DATABASE_USERNAME, DATABASE_PASSWORD);
 
         myStatement = myConnection.createStatement();
 
         myResultSet = myStatement.executeQuery(DATABASE_URL);
     }
     catch ( SQLException sqlException )
      {
         sqlException.printStackTrace();
         System.exit( 1 );
      } // end catch
     finally
     {
         try
         {
             myResultSet.close();
             myStatement.close();
             myConnection.close();
         } // end of try block
 
         catch ( SQLException SQLexception )
         {
            SQLexception.printStackTrace();
         } // end catch block
     } // end of finally
 
   } // end constructor
 
   // create and position GUI components; register event handlers
   private void createUserInterface()
   {
      // get content pane for attaching GUI components
      Container contentPane = getContentPane();
 
      // enable explicit positioning of GUI components 
      contentPane.setLayout( null );
 
      // set up restaurantJLabel
      restaurantJLabel = new JLabel("Restaurant");
      restaurantJLabel.setFont(new Font("Times New Roman", Font.BOLD, 14));
      restaurantJLabel.setBounds(30, 50, 100, 100);
 
      waiterJPanel = new JPanel();
      waiterJPanel.setLayout(null);
      waiterJPanel.setBounds(20, 50, 100, 100);
      waiterJPanel.setBorder(BorderFactory.createTitledBorder
      (BorderFactory.createEtchedBorder(),"Waiter Information"));
 
      menuItemsJPanel = new JPanel();
      menuItemsJPanel.setLayout(null);
      menuItemsJPanel.setBounds(20, 50, 200, 200);
      waiterJPanel.setBorder(BorderFactory.createTitledBorder
     (BorderFactory.createEtchedBorder(),"Menu Items"));
 
 
      calculateBillJButton = new JButton("Calculate Button");
      calculateBillJButton.setLayout(null);
      calculateBillJButton.setBounds(250, 250, 50, 50);
 
//     public void actionPerformed( ActionEvent event)
//     {
//        calculateBillJButtonActionPerformed( event );
//     } 
//     
      subtotalJLabel = new JLabel("Sub Total");
      subtotalJTextField = new JTextField();
 
      taxJLabel = new JLabel("Tax");
      taxJTextField = new JTextField();
 
      totalJLabel = new JLabel("Total");
      totalJTextField = new JTextField();
 
      // **** TODO ****** set properties of application's window
 
      // **** TODO ****** ensure database connection is closed
      // **** TODO ****** when user quits application
      addWindowListener(
 
         new WindowAdapter()anonymous inner class
         {
            //  event handler called when close button is clicked
            public void windowClosing( WindowEvent event )
            {
               frameWindowClosing( event );
            }
 
         } //  end anonymous inner class
 
      ); // end addWindowListener
 
   } // end method createUserInterface
 
   // **** TODO ****** set up waiterJPanel
   private void createWaiterJPanel()
   {
      // set up waiterJPanel
      waiterJPanel = new JPanel();
      waiterJPanel.setLayout( null );
      waiterJPanel.setBounds( 20, 152, 232, 152 );
      waiterJPanel.setBorder( BorderFactory.createTitledBorder( 
      BorderFactory.createEtchedBorder(), "Waiter Information" ) );
 
      // set up tableNumberJLabel
      tableNumberJLabel = new JLabel();
      tableNumberJLabel.setBounds( 8, 24, 80, 24 );
      tableNumberJLabel.setText( "Table Number:" );
      waiterJPanel.add( tableNumberJLabel );
 
      // set up tableNumberJTextField
      tableNumberJTextField = new JTextField();
      tableNumberJTextField.setBounds(10, 30, 90, 30);
      waiterJPanel.add( tableNumberJTextField );
 
      // set up waiterNameJLabel
      waiterNameJLabel = new JLabel();
      waiterNameJLabel.setBounds( 8, 24, 80, 24 );
      waiterNameJLabel.setText( "Waiter Name:" );
      waiterJPanel.add( waiterNameJLabel );
 
      // set up waiterNameJTextField
      waiterNameJTextField = new JTextField();
      waiterNameJTextField.setBounds(10, 30, 90, 30);
      waiterJPanel.add( waiterNameJTextField );
   } // end method createWaiterJPanel
 
 
    // create menuItemsJPanel
   private void createMenuItemsJPanel()
   {
      //  set up menuItemsJPanel
      menuItemsJPanel = new JPanel();
      menuItemsJPanel.setBounds( 20, 152, 232, 152 );
      menuItemsJPanel.setBorder( BorderFactory.createTitledBorder( 
         BorderFactory.createEtchedBorder(), "Menu Items" ) );
      menuItemsJPanel.setLayout( null );
//*******************************************************************
      //  set up beverageJLabel
      beverageJLabel = new JLabel();
      beverageJLabel.setBounds( 8, 24, 80, 24 );
      beverageJLabel.setText( "Beverage:" );
      menuItemsJPanel.add( beverageJLabel );
 
      // set up beverageJComboBox
      beverageJComboBox = new JComboBox();
      beverageJComboBox.setBounds( 88, 24, 128, 25 );
      menuItemsJPanel.add( beverageJComboBox );
      beverageJComboBox.addItemListener(
 
         new ItemListener()  // **** TODO ****** anonymous inner class
         {
            // **** TODO ****** event handler called when item in beverageJComboBox
            // **** TODO ****** is selected
            public void itemStateChanged( ItemEvent event )
            {
               beverageJComboBoxItemStateChanged( event );
            }
 
         } // end anonymous inner class
 
      ); // end addItemListener
 
      // add items to beverageJComboBox
      beverageJComboBox.addItem("Minerals");
      beverageJComboBox.addItem("Tea");
      beverageJComboBox.addItem("Coffee");
      beverageJComboBox.addItem("Minerla Water");
      beverageJComboBox.addItem("Fruit Juice");
      beverageJComboBox.addItem("Milk");
//******************************************************************
      // set up appetizerJLabel
      appetizerJLabel = new JLabel();
      appetizerJLabel.setBounds( 8, 24, 80, 24 );
      appetizerJLabel.setText( "Appetizer:" );
      menuItemsJPanel.add( appetizerJLabel );
 
      // set up appetizerJComboBox
      appetizerJComboBox = new JComboBox();
      appetizerJComboBox.setBounds( 88, 24, 128, 25 );
      menuItemsJPanel.add( appetizerJComboBox );
      beverageJComboBox.addItemListener(
 
         new ItemListener()  // **** TODO ****** anonymous inner class
         {
            // **** TODO ****** event handler called when item in beverageJComboBox
            // **** TODO ****** is selected
            public void itemStateChanged( ItemEvent event )
            {
               appetizerJComboBoxItemStateChanged( event );
            }
 
         } // end anonymous inner class
      ); // end addItemListener
 
      // add items to appetizerJComboBox
      appetizerJComboBox.addItem("Chicken Wings");
      appetizerJComboBox.addItem("Pate and Toast");
      appetizerJComboBox.addItem("Potato Skins");
      appetizerJComboBox.addItem("Nachos");
      appetizerJComboBox.addItem("Garlic Mushrooms");
      appetizerJComboBox.addItem("SeaFood Cocktail");
      appetizerJComboBox.addItem("Brie Cheese");
//****************************************************************
      // set up mainCourseJLabel
      mainCourseJLabel = new JLabel();
      mainCourseJLabel.setBounds( 8, 24, 80, 24 );
      mainCourseJLabel.setText( "Main Course:" );
      menuItemsJPanel.add( mainCourseJLabel );
 
      // set up mainCourseJComboBox
      mainCourseJComboBox = new JComboBox();
      mainCourseJComboBox.setBounds( 88, 24, 128, 25 );
      menuItemsJPanel.add( mainCourseJComboBox );
      mainCourseJComboBox.addItemListener(
 
      new ItemListener()  // **** TODO ****** anonymous inner class
         {
            // **** TODO ****** event handler called when item in beverageJComboBox
            // **** TODO ****** is selected
            public void itemStateChanged( ItemEvent event )
            {
               mainCourseJComboBoxItemStateChanged( event );
            }
 
         } // end anonymous inner class
      ); // end addItemListener
 
      // add items to mainCourseJComboBox
      mainCourseJComboBox.addItem("Seafood Alfredo");
      mainCourseJComboBox.addItem("Chicken Alfredo");
      mainCourseJComboBox.addItem("Lasagne");
      mainCourseJComboBox.addItem("Turkey Club");
      mainCourseJComboBox.addItem("Lobster Pie");
      mainCourseJComboBox.addItem("Rib Steak");
      mainCourseJComboBox.addItem("Scampi");
      mainCourseJComboBox.addItem("Turkey & Ham");
      mainCourseJComboBox.addItem("Chicken Kiev");
 //**********************************************************
 
      // set up dessertJLabel
      dessertJLabel = new JLabel();
      dessertJLabel.setBounds( 8, 24, 80, 24 );
      dessertJLabel.setText( "Main Course:" );
      menuItemsJPanel.add( dessertJLabel );
 
      // set up dessertJComboBox
      dessertJComboBox = new JComboBox();
      dessertJComboBox.setBounds( 88, 24, 128, 25 );
      menuItemsJPanel.add( dessertJComboBox );
      dessertJComboBox.addItemListener(
 
      new ItemListener()  // **** TODO ****** anonymous inner class
         {
            // **** TODO ****** event handler called when item in beverageJComboBox
            // **** TODO ****** is selected
            public void itemStateChanged( ItemEvent event )
            {
               dessertJComboBoxItemStateChanged( event );
            }
 
         } // end anonymous inner class
 
      ); // end addItemListener
 
         // add items to dessertJComboBox
      dessertJComboBox.addItem("Apple Pie");
      dessertJComboBox.addItem("Sundae");
      dessertJComboBox.addItem("Carrot Cake");
      dessertJComboBox.addItem("Mud Pie");
      dessertJComboBox.addItem("Pavlova");
 
   } // end method createMenuItemsJPanel
 //********************************************************************   
 
   // add items to JComboBox
   private void loadCategory(
      String category, JComboBox categoryJComboBox )
   {
      loadCategory("beverage", beverageJComboBox);
      loadCategory("appetizer", appetizerJComboBox);
      loadCategory("main course", mainCourseJComboBox);
      loadCategory("dessert", dessertJComboBox);
 
      try
      {
         myResultSet = myStatement.executeQuery("SELECT name FROM" + 
         "Menu WHERE category = "" + category + ");
 
         while(myResultSet.next())
         {
             categoryJComboBox.addItem(myResultSet.getString("name"));
         }
         myResultSet.close();
      } // end try block
      catch ( SQLException SQLexception )
        {
            SQLexception.printStackTrace();
            System.out.println("Cannot load Categories");
        } // end catch block         
 
   } // end method loadCategory
 
   // user select beverage
   private void beverageJComboBoxItemStateChanged( ItemEvent event )
   {
       // select an item
       if(event.getStateChange() == ItemEvent.SELECTED)
       {
          billItems.add((String)beverageJComboBox.getSelectedItem());
       }
 
   } // end of beverageJComboBoxItemStateChanged
 
 
   // user select appetizer
   private void appetizerJComboBoxItemStateChanged( ItemEvent event )
   {
       if(event.getStateChange() == ItemEvent.SELECTED)
       {
          billItems.add((String)appetizerJComboBox.getSelectedItem());
       }
 
   } // end method appetizerJComboBoxItemStateChanged
 
   // user select main course
   private void mainCourseJComboBoxItemStateChanged( 
      ItemEvent event )
   {
       if(event.getStateChange() == ItemEvent.SELECTED)
       {
          billItems.add((String)mainCourseJComboBox.getSelectedItem());
       }
 
 
   } // end method mainCourseJComboBoxItemStateChanged
 
   // user select dessert
   private void dessertJComboBoxItemStateChanged( ItemEvent event )
   {
       if(event.getStateChange() == ItemEvent.SELECTED)
       {
          billItems.add((String)dessertJComboBox.getSelectedItem());
       }
 
   } // end method dessertJComboBoxItemStateChanged
 
   // user click Calculate Bill JButton
   private void calculateBillJButtonActionPerformed( 
      ActionEvent event )
   {
   String tableNumber = tableNumberJTextField.getText().trim();
   String waiterName = waiterNameJTextField.getText().trim();
 
   if (tableNumber.length() == 0 || waiterName.length() == 0)
    {
       JOptionPane.showInputDialog("Information in Table Number and Waiter Name "
               + "must be entered");
    }
   else
   {
 
   }
 
 
   }// end method calculateBillJButtonActionPerformed
 
   // **** TODO ****** calculate subtotal
   private double calculateSubtotal()
   {
      return 0;
 
   } // end method calculateSubtotal
 
   // **** TODO ****** user close window
   private void frameWindowClosing( WindowEvent event )
   {
 
   }  // end method frameWindowClosing
 
   // **** TODO ****** method main
   public static void main( String[] args ) 
   {
     JFrame createUserInterface = new JFrame();
     createUserInterface.setSize(500, 500);
     createUserInterface.setVisible(true);
     createUserInterface.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
     createUserInterface.setLocationRelativeTo(null);
 
 
      // **** TODO ****** check command-line arguments
      if ( args.length == 2 )
      {
         // **** TODO ****** get command-line arguments
         String databaseUserName = args[ 0 ];
         String databasePassword = args[ 1 ];
 
         // **** TODO ****** create new RestaurantBillCalculator
         RestaurantBillCalculator application = new RestaurantBillCalculator ( 
         databaseUserName, databasePassword );
 
 
      }
      else
      {
         System.out.println( "Usage: java " + 
            "RestaurantBillCalculator databaseUserName databasePassword" );
      }
 
   } // end method main
 
} // end class RestaurantBillCalculator

Could you show me the line where you actually add any components to your frame?

This is way too much code to write before doing any testing and way too much code to post to determine why you are unable to display a JFrame.

Your code has errors. Are you getting error messages when you compile and/or run the code? You should be. Post your errors or other indications of bad behavior.

What's up with this line ( ~line 177 ):

new WindowAdapter()anonymous inner class

That's not a valid Java statement.

You see this is what i am not sure about, have i actually added anything to the frame, when I compile this, a window does appear but nothing in it, I'm not sure where i have went wrong here.

--- Update ---

You see i am taking this step by step according to the brief i have been given, im not worried about the WindowsAdapter part you are referring to just yet. I think my code is okay just a small disconnection somewhere hence why i am asking why no components are showing within the JFrame

ScreenHunter_40 Sep. 04 21.47.jpg

This is what its like when i compile, when i hit the x on the JFrame, BUild Successful appears in my output area :/

To add something to a JFrame you need to call the method add() on the content pane of the frame.
I can not find any place in your program where you are doing that (might be because you posted a huge amount of code).

Perhaps start with something smaller, just a frame with a single button or a label maybe. Once you got that working you can then try something bigger.

Originally Posted by copeg

a) I recommend NEVER using a null layout
b) I recommend answering the question posed in post #2

Unfortunately i have to use Null Layout, lecturer wants it for good practice purposes

--- Update ---

Originally Posted by Cornix

To add something to a JFrame you need to call the method add() on the content pane of the frame.
I can not find any place in your program where you are doing that (might be because you posted a huge amount of code).

Perhaps start with something smaller, just a frame with a single button or a label maybe. Once you got that working you can then try something bigger.

Well i wish i had the time, this is a project due in soon, i cant start with something small, hence why I am asking where i am going wrong with this program

Originally Posted by SeanyC

Unfortunately i have to use Null Layout, lecturer wants it for good practice purposes

I know they said you have to use the "null" as a good practice but when I was doing something from a brief it said use a "null" layout and I kept getting errors my point is if you listen to these guys they can really help you you do need to start small I know you said it's due in soon but the fact is with JAVA you have to start small and work up

Originally Posted by coderxx0

I know they said you have to use the "null" as a good practice but when I was doing something from a brief it said use a "null" layout and I kept getting errors my point is if you listen to these guys they can really help you you do need to start small I know you said it's due in soon but the fact is with JAVA you have to start small and work up

I just don't have the time I'm afraid, Hence I'm asking all of this, any
Other day of the week I would listen and would never use null layout
I've asked my lecturer now to figure out this problem

Originally Posted by copeg

Do you mean good practice - as in a good way to get better - or 'good practice' as in Best Practice? Because using null layout is far from best practice.

Good practice in a sense that when I am positioning components
such as Jcomboboxes i can position stuff with setBounds

Prob any other time I would not use it and my lecturer would
prob say not to use it also, just for this particular project

As I already said, make sure you add your components to your frame correctly. You can simply google "Add components to JFrame" and you should get plenty of tutorials, for example this one:
swing - Java - adding components to JFrame - Stack Overflow

Originally Posted by GregBrannon

This is way too much code to write before doing any testing and way too much code to post to determine why you are unable to display a JFrame.

Your code has errors. Are you getting error messages when you compile and/or run the code? You should be. Post your errors or other indications of bad behavior.

What's up with this line ( ~line 177 ):

new WindowAdapter()anonymous inner class

That's not a valid Java statement.

Can i just add to your post here and say that there was supposed to be two // in front of anonymous inner class, typo problems sorry

And what have you done with Cornix' suggestions?

Originally Posted by GregBrannon

And what have you done with Cornix' suggestions?

No i haven't, problem is i keep find examples with No argument constructors like this:
code not executing (Beginning Java forum at JavaRanch)

My constructor has two-arguments: public RestaurantBillCalculator( String databaseUserName, String databasePassword )

and this is in my main method
RestaurantBillCalculator application = new RestaurantBillCalculator (
databaseUserName, databasePassword );

What has that to do with adding components to your JFrame? (Post #13)

Originally Posted by copeg

You have been given ample advice, which from our vantage point seems as if it is being ignored. First, answer the question in post #2. If you cannot, or do not understand what that question means, then thoroughly read all the advice you have been given (esp. those posts by Cornix)

forget it, got someone else helping me