Help needed in refreshing a panel in my window.

Question

I have some problem in refreshing a panel of a window.
Here I am writting the sample code bellow.
My program contains 2 classes, one is "Test" other is "Testwindow".
class Test contains main(),displays the buttons reading from the string array obtained by listing a directory in my local file system through the panel p2 .If I click "Add" button in Test, class Testwindow's constructor is called & "Testwindow" is visible, which has a textfield. If you enter a string in the textfield, that string will be stored as a file in the same directory that the 1st window use. here I choose "C:\\temp" of my filesystem as the directory.
My requirement is:
when I enter a string in the textfield of Testwindow, then after clicking "Finish" button, that inputted string should be added to the panel p2 of 1st window(Test)during runtime.It means the panel p2 should be refreshed reading from the "C:\\temp" as soon as a new button is added to temp directory during runtime.
If any of you have idea over this,please help sending me the updated version of the code given below.
Regards.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
public class Test extends JFrame
     JPanel p1,p2;
     JButton b1,bdir[];
     File f;
     String s[];
     int n,nmax;
     public Test()
          super("Test");
          JPanel con=(JPanel)getContentPane();
          con.setLayout(new BorderLayout());
          addWindowListener(new WindowAdapter(){
               public void windowClosing(WindowEvent e)
                    System.exit(0);
          p1=new JPanel();
          p2=new JPanel();
          p2.setLayout(new GridLayout(nmax,1));
          b1=new JButton("Add");
          b1.addActionListener(new ActionListener(){
               public void actionPerformed(ActionEvent e)
                    if(e.getActionCommand()=="Add")
                         new Testwindow();
          p1.add(b1);
          f=new File("c:\\temp");
          s=f.list();
          n=s.length;
          nmax=n+20;
          bdir=new JButton[n];
          for(int i=0; i<n; i++)
               bdir=new JButton(s[i]);
               bdir[i].setHorizontalAlignment(AbstractButton.LEADING);
               p2.add(bdir[i]);
          int hor=ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED;
          int ver=ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED;
          JScrollPane jsp=new JScrollPane(p2,hor,ver);
          con.add(p1,"North");
          con.add(jsp,"Center");
          setSize(250,300);
     public static void main(String arg[])
          Test frame=new Test();
          frame.setVisible(true);
class Testwindow extends JFrame implements ActionListener
     JPanel p1,p2,p3;
     JLabel l1;
     JTextField tf1;
     JButton b1,b2;
     String s1, sdir[];
     public Testwindow()
          setTitle("Testwindow");
          Container con=getContentPane();
          con.setLayout(new BorderLayout());
          p1=new JPanel();
          p1.setLayout(new GridLayout(1,2));
          p2=new JPanel();
          l1=new JLabel("Enter a string: ");
          tf1=new JTextField();
          b1=new JButton("Finish");
          b1.addActionListener(this);
          p1.add(l1);
          p1.add(tf1);
          p2.add(b1);
          con.add(p1,"North");
          con.add(p2, "South");
          setSize(300,150);
          show();
     public void actionPerformed(ActionEvent e)
          if(e.getActionCommand()=="Finish"){
               try{
                    s1=tf1.getText();
                    File id_name=new File("C:\\temp\\"+s1+".txt");
                    FileOutputStream out=new FileOutputStream(id_name);
                    out.close();
               catch(IOException x)
                    System.out.println("Exception caught"+x);
               this.setVisible(false);

Answer 1

You have 2 JFrame's: Test and TestWindow
In order for TestWindow to send messages to Test it needs a reference of Test. Therefor write in TestWindow this:private Test parentFrame;
public void setParentFrame (Test t)
  parentFrame = t;
}... then after create an instance of TestWindow in Test call this method like this:...
TestWindow tw = new TestWindow ();
tw.setParentFrame (this);
...Next, in Test create a method that will be called when a string is inputted:public void sendString (String s)
  //update the panel or whatever
}call this method when the user clicks on a button or whatever in TestWindow:parentFrame.sendString (s);greetz,
Stijn