actionPerformed and exceptions help?

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actionPerformed and exceptions help?

 
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  #1
Feb 11th, 2007
Hi this is my first post here:cheesy:.
I'm having a problem with how to throw exception in an applet and how to add actionPerformed to other buttons.
This applet calculates the sqare roots of an equation.
It calculates the stuf ok but the thing is that I want to throw an
exception when any of the TextFields are emty. Other thing I want the
RESET Button to clear the TextFields when clicked.
This is the code:
Java Syntax (Toggle Plain Text) 
  1. import java.awt.*;
  2. import java.awt.event.*;
  3. import java.applet.*;
  4. import javax.swing.*;
  5. import java.lang.*;
  6. import java.lang.String;
  7.  
  8. public class Kv extends java.applet.Applet implements ActionListener {
  9.  
  10.  
  11.  
  12.     public class Isklucok extends NumberFormatException
  13.         {
  14.             public Isklucok()
  15.             {
  16.                 super("Enter a number.");
  17.             }
  18.         }
  19.  
  20.  
  21.      Label aa = new Label("a:");
  22.      Label bb = new Label("b:");
  23.      Label cc = new Label("c:");
  24.  
  25.      TextField A = new TextField();
  26.      TextField B = new TextField();
  27.      TextField C = new TextField();
  28.  
  29.      Button otkaz = new Button("Reset");
  30.      Button calc = new Button("Calculate");
  31.  
  32.     double X1, X2, a, b, c, D;
  33.  
  34.     public void init() {
  35.  
  36.         setLayout(new GridLayout(4,2));
  37.         add(aa);
  38.         add(A);
  39.         add(bb);
  40.         add(B);
  41.         add(cc);
  42.         add(C);
  43.         add(otkaz);
  44.         add(calc);
  45.  
  46.         calc.addActionListener(new Racunaj()); 
  47.         otkaz.addActionListener(this);
  48.         }
  49.  
  50.         class Racunaj implements ActionListener throws new Isklucok() 
  51.  
  52.        {
  53.             public void actionPerformed(ActionEvent e) 
  54.             {
  55.  
  56.                 a = Double.parseDouble(A.getText());  
  57.                    b = Double.parseDouble(B.getText());  
  58.                 c = Double.parseDouble(C.getText());    
  59.  
  60.                 D = (b*b-4*a*c);
  61.  
  62.                 X1 = ((-b)-Math.sqrt(D))/(2*a);     
  63.                 X2 = ((-b)+Math.sqrt(D))/(2*a);    
  64.  
  65.                 if(D>0)
  66.                 JOptionPane.showMessageDialog(this, "the numbers are real: "+X1+" , "+X2);
  67.                 else if(D<0)
  68.                 JOptionPane.showMessageDialog(this, "the numbers are komplex");
  69.                 else
  70.                 JOptionPane.showMessageDialog(this, "the numbers are real and equal. "+X1+" , "+X2);
  71.  
  72.  
  73.                 if ((A.getText()==null)||(B.getText()==null)||(C.getText()==null)) throw new Isklucok();
  74.  
  75.  
  76.             }
  77.  
  78.  
  79.        }
  80.        public class Zaebi extends Kv implements ActionListener 
  81.             {
  82.                 A.setText("");
  83.                 B.setText="";
  84.                 C.setText="";
  85.             }
  86. }

the html code is:

Java Syntax (Toggle Plain Text) 
  1. <html>
  2.     <head>
  3.     </head>
  4.     <body bgcolor="000000">
  5.         <center>
  6.             <applet
  7.                 code    = "Kv.class"
  8.                 width    = "250"
  9.                 height    = "125"
  10.                 >
  11.             </applet>
  12.         </center>
  13.     </body>
  14. </html>

Any kind of HELP is welcome.
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Re: actionPerformed and exceptions help?

 
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  #2
Feb 11th, 2007
http://www.javacoffeebreak.com/java107/java107.html
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