extends Frame help

[kieran pattni]

import java.awt.*;
import java.awt.event.*;
public class CheckgroupApp extends Frame
implements ItemListener

private CheckboxGroup nn = new CheckboxGroup();
public showGui()
{
setLayout(new GridLaout(4,1);
add()//
seVisible();//without using instance of Frame class..i dont understand..


///some code

my question is why i have to use an instane of Frame class to add components directly..

[Michael Dunn]

> my question is why i have to use an instane of Frame class to add components directly..

you need on instance of a Frame/JFrame to work with - it is a top level container

either

class SomeClass extends JFrame
{
  public SomeClass()
  {
    add(someComponent);//pre 1.5 - getContentPane().add(someComponent);
  }
}
 
or
 
class SomeClass
{
  public SomeClass()
  {
    JFrame f = new JFrame();    
    f.add(someComponent);//pre 1.5 - f.getContentPane().add(someComponent);
  }
}

[kieran pattni]

sorry my error..Q? was why i dont have to use a instance of the Frame class..

[Michael Dunn]

> sorry my error..Q? was why i dont have to use a instance of the Frame class..

by extending Frame, the class is a Frame, and inherits all the methods of Frame