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Help on an applet

Posted on 2002-04-05
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Last Modified: 2013-11-23
   I'm trying to make an applet with checkboxes and it would have many different comibinations of if statements to get this done for the appropriate boxes checked, but I am faced with two problems. First, the if statements get really long because I have to indicate not only which box is checked, but also which one is not for it to work properly (at least from my way of doing it). Is there a way to reduce this?
    Also, since the statements are really long, so is my CheckBoxListener class. Is there a way to make this a seprate class in order to make my applet class shorter and easier to read? Here's my code. By the way, any other pionters would be much obliged.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class WarApplet extends JApplet {
    JCheckBox englandButton = new JCheckBox("England");
    JCheckBox franceButton = new JCheckBox("France");
    JCheckBox russiaButton = new JCheckBox("Russia");
    JCheckBox unitedStatesButton = new JCheckBox("United States");

    JTextArea txt = new JTextArea("Please choose a country.",10, 10);
   
    public void init() {
      englandButton.setSelected(false);
      franceButton.setSelected(false);
      russiaButton.setSelected(false);
      unitedStatesButton.setSelected(false);
      
      Container cp = getContentPane();

      JPanel checkPanel = new JPanel();
      checkPanel.setLayout(new GridLayout(0,1));
      checkPanel.add(englandButton);
      checkPanel.add(franceButton);
      checkPanel.add(russiaButton);      
      checkPanel.add(unitedStatesButton);
      cp.add(checkPanel, BorderLayout.WEST);

      txt.setLineWrap(true);
      txt.setWrapStyleWord(true);
      txt.setEditable(false);
      cp.add(txt, BorderLayout.CENTER);
      
      englandButton.addItemListener(new CheckBoxListener());
      franceButton.addItemListener(new CheckBoxListener());
      russiaButton.addItemListener(new CheckBoxListener());
      unitedStatesButton.addItemListener(new CheckBoxListener());
    }

    class CheckBoxListener implements ItemListener {
      public void itemStateChanged(ItemEvent e) {
          if (englandButton.isSelected() &&
            !franceButton.isSelected() &&
            !russiaButton.isSelected() &&
            !unitedStatesButton.isSelected())
            txt.setText(WarInfo.info[0]);
          else if (!englandButton.isSelected() &&
                 franceButton.isSelected() &&
                 !russiaButton.isSelected() &&
                 !unitedStatesButton.isSelected())
            txt.setText(WarInfo.info[1]);
          else if (!englandButton.isSelected() &&
                 !franceButton.isSelected() &&
                 russiaButton.isSelected() &&
                 !unitedStatesButton.isSelected())
            txt.setText(WarInfo.info[2]);
          else if (!englandButton.isSelected() &&
                 !franceButton.isSelected() &&
                 !russiaButton.isSelected() &&
                 unitedStatesButton.isSelected())
            txt.setText(WarInfo.info[3]);
          else if (englandButton.isSelected() &&
                 franceButton.isSelected() &&
                 russiaButton.isSelected() &&
                 unitedStatesButton.isSelected())
            txt.setText(WarInfo.info[4]);
          else if (!englandButton.isSelected() &&
                 franceButton.isSelected() &&
                 !russiaButton.isSelected() &&
                 unitedStatesButton.isSelected())
            txt.setText(WarInfo.info[5]);
          else if (!englandButton.isSelected() &&
                 !franceButton.isSelected() &&
                 russiaButton.isSelected() &&
                 unitedStatesButton.isSelected())
            txt.setText(WarInfo.info[6]);
          else if (englandButton.isSelected() &&
                 franceButton.isSelected() &&
                 !russiaButton.isSelected() &&
                 !unitedStatesButton.isSelected())
            txt.setText(WarInfo.info[7]);
          else if (englandButton.isSelected() &&
                 !franceButton.isSelected() &&
                 !russiaButton.isSelected() &&
                 unitedStatesButton.isSelected())
            txt.setText(WarInfo.info[8]);
          else if (englandButton.isSelected() &&
                 franceButton.isSelected() &&
                 russiaButton.isSelected() &&
                 !unitedStatesButton.isSelected())
            txt.setText(WarInfo.info[9]);
          else txt.setText("Please choose a country.");
      }
    }
   
}

   
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Question by:alrav79
11 Comments
 
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Accepted Solution

by:
objects earned 50 total points
Comment Utility
>  Is there a way to make this a seprate class

It actually already is a seperate class :-) It's what's called an inner class.
You are free to make it a non-inner class, just move it into it's own .java file CheckBoxListener.java.

It's not entirely clear what you're trying to do, so I can't really comment on improvements to your logic.

A minor side note, you don't actually appear to need seperate instance of your listener for each cb, one would suffice.
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Expert Comment

by:cini_gm
Comment Utility
This way u can break this class. Save the two classes in the same directory and compile it

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class WarApplet extends JApplet {
   JCheckBox englandButton = new JCheckBox("England");
   JCheckBox franceButton = new JCheckBox("France");
   JCheckBox russiaButton = new JCheckBox("Russia");
   JCheckBox unitedStatesButton = new JCheckBox("United States");

   JTextArea txt = new JTextArea("Please choose a country.",10, 10);
   
   public void init() {
     englandButton.setSelected(false);
     franceButton.setSelected(false);
     russiaButton.setSelected(false);
     unitedStatesButton.setSelected(false);
     
     Container cp = getContentPane();

     JPanel checkPanel = new JPanel();
     checkPanel.setLayout(new GridLayout(0,1));
     checkPanel.add(englandButton);
     checkPanel.add(franceButton);
     checkPanel.add(russiaButton);    
     checkPanel.add(unitedStatesButton);
     cp.add(checkPanel, BorderLayout.WEST);

     txt.setLineWrap(true);
     txt.setWrapStyleWord(true);
     txt.setEditable(false);
     cp.add(txt, BorderLayout.CENTER);
     
     englandButton.addItemListener(new CheckBoxListener());
     franceButton.addItemListener(new CheckBoxListener());
     russiaButton.addItemListener(new CheckBoxListener());
     unitedStatesButton.addItemListener(new CheckBoxListener());
   }
}

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class CheckBoxListener implements ItemListener {
     public void itemStateChanged(ItemEvent e) {
         if (englandButton.isSelected() &&
          !franceButton.isSelected() &&
          !russiaButton.isSelected() &&
          !unitedStatesButton.isSelected())
          txt.setText(WarInfo.info[0]);
         else if (!englandButton.isSelected() &&
               franceButton.isSelected() &&
               !russiaButton.isSelected() &&
               !unitedStatesButton.isSelected())
          txt.setText(WarInfo.info[1]);
         else if (!englandButton.isSelected() &&
               !franceButton.isSelected() &&
               russiaButton.isSelected() &&
               !unitedStatesButton.isSelected())
          txt.setText(WarInfo.info[2]);
         else if (!englandButton.isSelected() &&
               !franceButton.isSelected() &&
               !russiaButton.isSelected() &&
               unitedStatesButton.isSelected())
          txt.setText(WarInfo.info[3]);
         else if (englandButton.isSelected() &&
               franceButton.isSelected() &&
               russiaButton.isSelected() &&
               unitedStatesButton.isSelected())
          txt.setText(WarInfo.info[4]);
         else if (!englandButton.isSelected() &&
               franceButton.isSelected() &&
               !russiaButton.isSelected() &&
               unitedStatesButton.isSelected())
          txt.setText(WarInfo.info[5]);
         else if (!englandButton.isSelected() &&
               !franceButton.isSelected() &&
               russiaButton.isSelected() &&
               unitedStatesButton.isSelected())
          txt.setText(WarInfo.info[6]);
         else if (englandButton.isSelected() &&
               franceButton.isSelected() &&
               !russiaButton.isSelected() &&
               !unitedStatesButton.isSelected())
          txt.setText(WarInfo.info[7]);
         else if (englandButton.isSelected() &&
               !franceButton.isSelected() &&
               !russiaButton.isSelected() &&
               unitedStatesButton.isSelected())
          txt.setText(WarInfo.info[8]);
         else if (englandButton.isSelected() &&
               franceButton.isSelected() &&
               russiaButton.isSelected() &&
               !unitedStatesButton.isSelected())
          txt.setText(WarInfo.info[9]);
         else txt.setText("Please choose a country.");
     }
   }
   

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Expert Comment

by:objects
Comment Utility
Yes, you'll need to pass reference to the relevant objects or provide methods to perform required functionality.
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Expert Comment

by:objects
Comment Utility
The same way ANY classes would interact.
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Author Comment

by:alrav79
Comment Utility
ok, I now put the classes in their own appropriate files, and both of them compile perfectly. But when the applet loads, it acts as if the if statements arent there. No matter what i check, there is no response. I passed reference by making a WarApplet object "a" in the CheckBoxListener class, like this:

WarApplet a  = new WarApplet();
...
...
..
if (a.england.isSelected())
..
you get the point
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Expert Comment

by:CEHJ
Comment Utility
A more elegant way to do this would be to take a bit masking approach. You'll find if you create an array of checkboxes, this may help in connection with this way of doing things.

final static int FRANCE =  1 << 0;
final static int ENGLAND = 1 << 1;
...

final static int FRANCE_ENGLAND = ENGLAND | FRANCE;


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Expert Comment

by:objects
Comment Utility
You need to pass a reference of WarApplet to you listener class, not create a new one.
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Author Comment

by:alrav79
Comment Utility
explain how please with an example
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Expert Comment

by:objects
Comment Utility
public CheckBoxListener(WarApplet applet)
{
   a = applet;
}
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Expert Comment

by:Venci75
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No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:
Answered by: objects
Please leave any comments here within the next seven days.
 
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!
 
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by:SpideyMod
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per recommendation

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