wrong output

[oghenekaro EFEKODO]

need help in identifying the problem with my program.anytime i run and compute the values i get a wrong answer.thanks for ever listening hears.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class CombGUI extends JPanel implements ActionListener{
JTextArea output;
JTextField input1,input2,input3;
javax.swing.JButton bibutton;
public CombGUI(){
setLayout(null);
javax.swing.JLabel input1L=new javax.swing.JLabel("Number of Trials(N):");
input1L.setBounds(10,50,250,30);
add(input1L);
input1=new JTextField(5);
input1.setBounds(150,50,50,30);
add(input1);
javax.swing.JLabel input2L=new javax.swing.JLabel("Number of Success in N Trials(X):");
input2L.setBounds(10,80,250,30);
add(input2L);
input2=new JTextField(5);
input2.setBounds(200,80,50,30);
add(input2);
javax.swing.JLabel input3L=new javax.swing.JLabel("Probality of Success(p):");
input3L.setBounds(10,110,250,30);
add(input3L);
input3=new JTextField(10);
input3.setBounds(150,110,50,30);
add(input3);
bibutton=new javax.swing.JButton("Bianomial Distribution");
bibutton.setBounds(255,140,150,30);
bibutton.addActionListener(this);
add(bibutton);
output=new JTextArea();
output.setBounds(100,170,500,30);
add(output);
}
public void actionPerformed(ActionEvent e){
try{
String s1=input1.getText();
String s2=input2.getText();
String s3=input3.getText();
int n=Integer.parseInt(s1);
int x=Integer.parseInt(s2);
double p=Double.parseDouble(s3);
if(e.getSource()==bibutton){
long answer=this.binomial(n,x,p);
output.setText(Long.toString(answer));
}
}
catch(Exception ex){System.out.println(ex);}
}
public long factorial(int n){
long fact=1;
if(n==0)
return 1;
else
return n*factorial(n-1);
}
public long comb(int n,int r){
return factorial(n)/(factorial(r)*factorial(n-r));
}
public long binomial(int n,int x,double p){
return (long)(comb(n,x)*Math.pow((p),x)*Math.pow((1-p),(n-x)));
}
public static void main(String[] k){
CombGUI cm=new CombGUI();
JFrame f=new JFrame();
f.setSize(500,500);
f.setVisible(true);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Container c=f.getContentPane();
c.add(cm);
}
} 

[Campbell Ritchie]

It is the cast that is the problem; with likely values for p, you end up with a fractional result; if you cast it to an integral number, that converts it to 0. Get rid of the cast and return a double from the comb(int, int, double) method.

[edit] not comb(int, int, double), but binomial(int, int, double) [/edit]
[ November 12, 2006: Message edited by: Campbell Ritchie ]

[oghenekaro EFEKODO]

i removed the casting and it gave me an error message("possible loss of precission").please could you gave me a sample of what to add or to rovemove.thanks in advance.

[jide agboola]

Can i get some understanding why you inherit from JPanel, and not JFrame?(anybody help please)

[Tim LeMaster]

Well if you inherit from JPanel you could put this panel in an container you choose. However JFrame is a top level container and has support for window events (like closing), menus, etc.

In this small example I don't think its very important. But you won't find yourself extending JFrame very often if at all. You don't need to extend JFrame to make a swing app - just use the existing class.

Of course this class doesn't need to extend JPanel either it could create it by composition then add the internal JPanel to the Frame.