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Thread: Trouble with my applet

  1. #1
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    Exclamation Trouble with my applet

    Hey folks,
    i've been working on this program here, and i've hit a roadblock. Everything compiles fine, and it runs alright. As you can see from the code, there's a window that opens with two buttons, one to display the contents of the ArrayList and another with a form that allows you to add a contact. The latter will not work, however, and i can't for the life of me figure out why. Here's the code, any help would be appreciated.

    /**
     * This applet runs and provides two options; saving a new contact or displaying the database. Choosing to
     * view the database opens a window that will display the contents of the database. Choosing to save a new
     * contact will open up a window with a form that allows for the creation of a contact. Eventually, the 
     * program will save this database into a .txt file, allowing for permanent storage of the ArrayList of 
     * contacts present in the interface Storage.
     * 
     * Cdeed  
     * 4/28/11 
     * version 1.3
     */
    import java.util.*;
    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    public class MainPage extends JApplet implements Storage
    {
        public void init()
        {
            JLabel title = new JLabel("Contact Database");
            JButton save = new JButton("New Contact");
            save.addActionListener(new ButtonListener());
            JButton view = new JButton("View Database");
            view.addActionListener(new ButtonListener1());
     
            Container c = getContentPane();
            c.setBackground(Color.WHITE);
            c.setLayout(new BoxLayout(c, BoxLayout.PAGE_AXIS));
            c.add(title);
            c.add(save);
            c.add(view);
        }
     
        private class ButtonListener implements ActionListener
        {
            private JTextField input, i1, i2, i3, i4;
            public void actionPerformed(ActionEvent event)
            {
                JFrame frame = new JFrame("New Contact");
                frame.getContentPane().setBackground(Color.WHITE);
                frame.getContentPane().setLayout(new FlowLayout());
     
                JLabel label = new JLabel ("Name");
                input = new JTextField (15);
     
                JLabel l1 = new JLabel ("Address");
                i1 = new JTextField (30);
     
                JLabel l2 = new JLabel ("Cell Number");
                i2 = new JTextField (15);
     
                JLabel l3 = new JLabel ("Home Number");
                i3 = new JTextField (15);
     
                JLabel l4 = new JLabel ("E-Mail");
                i4 = new JTextField (30);
     
                JButton save = new JButton("Save");
                save.addActionListener(new ButtonListener2());
     
                frame.getContentPane().add(save);
                frame.getContentPane().setLayout(new BoxLayout(frame, BoxLayout.PAGE_AXIS));
                frame.getContentPane().add(label);
                frame.getContentPane().add(input);
                frame.getContentPane().add(l1);
                frame.getContentPane().add(i1);
                frame.getContentPane().add(l2);
                frame.getContentPane().add(i2);
                frame.getContentPane().add(l3);
                frame.getContentPane().add(i3);
                frame.getContentPane().add(l4);
                frame.getContentPane().add(i4);
                frame.pack();
                frame.setVisible(true);
            }
     
            private class ButtonListener2 implements ActionListener
            {
                public void actionPerformed(ActionEvent event)
                {
                    Person p1 = new Person(i2.getText(), i3.getText(), input.getText(), i1.getText(), i4.getText());
                    contacts.add(p1);
                    input.setText("Saved!");
                    i1.setText("Saved!");
                    i2.setText("Saved!");
                    i3.setText("Saved!");
                    i4.setText("Saved!");
                }
            }
        }
     
        private class ButtonListener1 implements ActionListener
        {
            public void actionPerformed(ActionEvent event)
            {
     
                JFrame frame = new JFrame("Contacts");
                frame.getContentPane().setBackground(Color.WHITE);
                frame.getContentPane().setLayout(new FlowLayout());
     
                for(Person a: contacts)
                {
                    JLabel b1 = new JLabel(a.toString());
                    frame.getContentPane().add(b1);
                }
     
                frame.pack();
                frame.setVisible(true);
            }
        }
    }
    Last edited by cdeed; April 29th, 2011 at 08:35 AM. Reason: Put code tags around code


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Trouble with my applet

    What do you mean when you say that it "will not work"?
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  3. #3
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    Default Re: Trouble with my applet

    Sorry, i should have been more clear. When the first JFrame opens up in my editor's (BlueJ) applet viewer, it displays the two JButtons "save" and "view". When "view" is clicked on, another JFrame is opened that would contain the ArrayList full of contacts were it filled with some. When "save" is pressed, it should open a new JFrame that contains several JLabels and JTextFields that allow the user to input information such as a name, address, phone number etc. Instead, clicking the button does nothing, not even opening a new JFrame. I'm not sure if this is due to the ButtonListener classes, or if i'm missing something else entirely. If past experience is anything to go by, then it's probably something relatively simple that i can't seem to find. If you need any additional code, like possibly the Storage interface, i can post that as well.

  4. #4
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Trouble with my applet

    Hmm, this seems like it should work. Are you sure the JFrame isn't just popping up under the window the applet is in?

    I'd love to test this, but I can't do that without an SSCCE- the shorter, the better.
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  5. #5
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    Default Re: Trouble with my applet

    I checked under the window, it's not there. The other button pops up fine enough, so i'm not entirely sure. As for the SSCCE, it compiles but i can't exactly guarantee that i didn't accidentally take out the problem; hopefully that's not the case.

    import java.util.*;
    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    public class MainPage2 extends JApplet
    {
        public void init()
        {
            JButton save = new JButton("New Contact");
            save.addActionListener(new ButtonListener());
     
            Container c = getContentPane();
            c.setLayout(new BoxLayout(c, BoxLayout.PAGE_AXIS));
            c.add(save);
        }
     
        private class ButtonListener implements ActionListener
        {
            private JTextField input, i1, i2, i3, i4;
            public void actionPerformed(ActionEvent event)
            {
                JFrame frame = new JFrame("New Contact");
                frame.getContentPane().setBackground(Color.WHITE);
                frame.getContentPane().setLayout(new FlowLayout());
     
                frame.getContentPane().setLayout(new BoxLayout(frame, BoxLayout.PAGE_AXIS));
     
                frame.setSize(100, 50);
                frame.setVisible(true);
            }
     
            private class ButtonListener2 implements ActionListener
            {
                public void actionPerformed(ActionEvent event)
                {
                }
            }
        }
    }
    Last edited by cdeed; April 29th, 2011 at 12:36 PM.

  6. #6
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    Default Re: Trouble with my applet

    Ah, the problem is this line:

    frame.getContentPane().setLayout(new BoxLayout(frame, BoxLayout.PAGE_AXIS));

    You're setting the layout of the JFrame's contentPane, but you're passing the JFrame (not the contentPane) into the BoxLayout constructor. This is generating an exception, which causes the method to exit before it shows the JFrame.

    Exception in thread "AWT-EventQueue-1" java.awt.AWTError: BoxLayout can't be shared
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  7. The Following User Says Thank You to KevinWorkman For This Useful Post:

    cdeed (April 29th, 2011)

  8. #7
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    Default Re: Trouble with my applet

    Ahh, i would have never seen that. Thank you!

  9. #8
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    Default Re: Trouble with my applet

    No problem. It can be confusing because JFrame contains a few methods that actually are just convenience methods that access the contentPane automatically. So calling JFrame.setLayout() is actually the same as calling JFrame.getContentPane().setLayout(). Same with the add() method, and a couple others.

    Anyway, glad you got it sorted.
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