well i am a newbie in java programming...i want to make a frame and button display program in which when the button is clicked then it prompts user to enter the value...but i am getting a exception throw error..i dont know exactly where to place the file " throws IOException" in code...plzzzzzzzzzzz help me out
here is the code

import java.awt.*;
import java.awt.event.*;
import java.io.*;

class ButtonFrame extends Frame

implements ActionListener , WindowListener
{
Button button;
Button button1;
Button button2;
Button button3;
double l,w,h;
ButtonFrame(String s)
{ super(s);
setBackground(Color.magenta);
setSize(500,400);
setLayout(new FlowLayout());
addWindowListener(this);
button = new Button("Length");
button1= new Button("Width");
button2 = new Button("Height");
button3 = new Button("Volume");
add(button);
add(button1);
add(button2);
add(button3);
button.addActionListener(this);
button1.addActionListener(this);
button2.addActionListener(this);
button3.addActionListener(this);
setVisible(true);
}

public void windowClosed(WindowEvent event){}
public void windowDeiconified(WindowEvent event){}
public void windowIconified (WindowEvent event){}
public void windowActivated(WindowEvent event){}
public void windowDeactivated(WindowEvent event){}
public void windowOpened(WindowEvent event){}

public void windowClosing(WindowEvent event)
{ System.exit(0);
}

public void actionPerformed(ActionEvent event)
{ if (event.getActionCommand().equals("Length"))

{
InputStreamReader reader = new InputStreamReader(System.in);
BufferedReader input = new BufferedReader (reader);
System.out.println("Enter Length:");
String text= input.readLine();
Double x = new Double(text);
l = x.doubleValue();
}

if (event.getActionCommand().equals("Width"))

{
InputStreamReader reader = new InputStreamReader(System.in);
BufferedReader input = new BufferedReader (reader);
System.out.println("Enter Width:");
String text= input.readLine();
Double x = new Double(text);
w = x.doubleValue();
}

if (event.getActionCommand().equals("Height"))

{
InputStreamReader reader = new InputStreamReader(System.in);
BufferedReader input = new BufferedReader (reader);
System.out.println("Enter Height:");
String text= input.readLine();
Double x = new Double(text);
h = x.doubleValue();
}
if (event.getActionCommand().equals("Volume"))
{ System.out.println("The Volume of Figure ");

Double volume = l*w*h;
System.out.println("is" +volume);
}
}
}


class TestButtonFrame2
{ public static void main (String[] args)
{ ButtonFrame buttonFrame = new ButtonFrame("Volume Calculator");
}
}