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Applet Calculator

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Join Date: Feb 2007
Posts: 3
Reputation: PennyBoki is an unknown quantity at this point 
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PennyBoki PennyBoki is offline Offline
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Applet Calculator

 
-1
  #1
Feb 12th, 2007
the errors are commented in the code:
help???

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.  
  7.  
  8. public class Kol2_1 extends Applet implements ActionListener
  9. {
  10.     Button plus  = new Button("+");
  11.     Button minus = new Button("-");
  12.     Button times = new Button("*");
  13.     Button div   = new Button("/");
  14.     Button eq    = new Button("=");
  15.  
  16.     TextField pole = new TextField("E hej zver");
  17.  
  18.     double x=0.0,y=0.0, z;        
  19.  
  20.  
  21.     public void init()
  22.     {    
  23.         try{
  24.         x=Double.parseDouble(JOptionPane.showInputDialog("Vnesete vrednost za x:"));
  25.         y=Double.parseDouble(JOptionPane.showInputDialog("Vnesete vrednost za y:"));
  26.            }
  27.         catch(StringIndexOutOfBoundsException n)
  28.         {JOptionPane.showMessageDialog(this, "Vnesete broj.");}    
  29.  
  30.         setLayout(new GridLayout(4,2));
  31.         add(plus);
  32.         add(minus);
  33.         add(times);
  34.         add(div);
  35.         add(eq);
  36.         add(pole);
  37.  
  38.         plus.addActionPerformed(this);  /*cannot find symbol method addActionPerformed(Kol2_1)*/
  39.         minus.addActionPerformed(this);  /*cannot find symbol method addActionPerformed(Kol2_1)*/
  40.         times.addActionPerformed(this);  /*cannot find symbol method addActionPerformed(Kol2_1)*/
  41.         div.addActionPerformed(this);   /*cannot find symbol method addActionPerformed(Kol2_1)*/
  42.         eq.addActionPerformed(this);   /*cannot find symbol method addActionPerformed(Kol2_1)*/
  43.  
  44.  
  45.  
  46.  
  47.     }
  48.  
  49.     public void actionPerformed(ActionEvent e)
  50.         {
  51.             switch(e.getSource()){            //incompatible types
  52.                 case    plus:     {    z=x+y;}
  53.                 case    minus:  {    z=x-y;}
  54.                 case    times:  {    z=x*y;}
  55.                 case    div:    {    try{z=x/y;}
  56.                                     catch(NumberFormatException m)
  57.                                     {
  58.                                         if(y==0) JOptionPane.showMessageDialog(this,"Division by zero.");
  59.                                     }
  60.                                 }
  61.                 case    eq:     {pole.setText(""+z);}
  62.             }
  63.     }
  64. }
Last edited by PennyBoki; Feb 12th, 2007 at 7:42 pm.
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Join Date: Nov 2005
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Reputation: Cudmore is an unknown quantity at this point 
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Cudmore Cudmore is offline Offline
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Re: Applet Calculator

 
0
  #2
Feb 12th, 2007
*squints at code*

.....

Haha, silly me. I missed this at first glance.

1) instead of *.addActionPerformed(this); use *.addActionListener(this);

2) e.getSource() returns an Object, and switch statements work with int values. Might wanna reconsider, with casting and/or an if-else statement.
synchronized (theWorld) { System.out.println ("It's all mine..."); }
How many people have code in their Sigs?
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muthulakshmil muthulakshmil is offline Offline
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Re: Applet Calculator

 
0
  #3
Feb 12th, 2007
you are giving plus.addactionPerformed(this);. you should not give like that. please give plus.addActionListener(this);. and then after finishing the constructor write the method

public void actionPerformed(ActionEvent e)
{
String s=e.getActionCommand();
if(s.equals("+"))
{....}
}

here e.getActionCommand() method return the caption(that is the string that you written on the button). and then check whether it it equal to +,-,*,/ and then perform the relevant action.







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Originally Posted by PennyBoki View Post
the errors are commented in the code:
help???

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.  
  7.  
  8. public class Kol2_1 extends Applet implements ActionListener
  9. {
  10.     Button plus  = new Button("+");
  11.     Button minus = new Button("-");
  12.     Button times = new Button("*");
  13.     Button div   = new Button("/");
  14.     Button eq    = new Button("=");
  15.  
  16.     TextField pole = new TextField("E hej zver");
  17.  
  18.     double x=0.0,y=0.0, z;        
  19.  
  20.  
  21.     public void init()
  22.     {    
  23.         try{
  24.         x=Double.parseDouble(JOptionPane.showInputDialog("Vnesete vrednost za x:"));
  25.         y=Double.parseDouble(JOptionPane.showInputDialog("Vnesete vrednost za y:"));
  26.            }
  27.         catch(StringIndexOutOfBoundsException n)
  28.         {JOptionPane.showMessageDialog(this, "Vnesete broj.");}    
  29.  
  30.         setLayout(new GridLayout(4,2));
  31.         add(plus);
  32.         add(minus);
  33.         add(times);
  34.         add(div);
  35.         add(eq);
  36.         add(pole);
  37.  
  38.         plus.addActionPerformed(this);  /*cannot find symbol method addActionPerformed(Kol2_1)*/
  39.         minus.addActionPerformed(this);  /*cannot find symbol method addActionPerformed(Kol2_1)*/
  40.         times.addActionPerformed(this);  /*cannot find symbol method addActionPerformed(Kol2_1)*/
  41.         div.addActionPerformed(this);   /*cannot find symbol method addActionPerformed(Kol2_1)*/
  42.         eq.addActionPerformed(this);   /*cannot find symbol method addActionPerformed(Kol2_1)*/
  43.  
  44.  
  45.  
  46.  
  47.     }
  48.  
  49.     public void actionPerformed(ActionEvent e)
  50.         {
  51.             switch(e.getSource()){            //incompatible types
  52.                 case    plus:     {    z=x+y;}
  53.                 case    minus:  {    z=x-y;}
  54.                 case    times:  {    z=x*y;}
  55.                 case    div:    {    try{z=x/y;}
  56.                                     catch(NumberFormatException m)
  57.                                     {
  58.                                         if(y==0) JOptionPane.showMessageDialog(this,"Division by zero.");
  59.                                     }
  60.                                 }
  61.                 case    eq:     {pole.setText(""+z);}
  62.             }
  63.     }
  64. }
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Join Date: Feb 2007
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PennyBoki PennyBoki is offline Offline
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Re: Applet Calculator

 
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  #4
Feb 13th, 2007
thanks alot
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