How to make flowlayout available in its caller??

Question

Dear friends:
Good weekends.
I met a problem when I tried to call a Flowlayout Program from another program.
I have a Flowlayout Program called FlowLayoutPane.java, it can display 20 buttons in FlowLayout, run successes, I write another program called FlowLayoutPaneCall.java to call FlowLayoutPane, these 20 icons display also, but not what I want, I need these 20 buttons display in FlowLayoutPaneCall exactly as same as they display in FlowLayoutPane.java, How can I do that??
[1]. FlowLayoutPane.java
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class FlowLayoutPane extends JPanel {
  public FlowLayoutPane() {
    this.setLayout(new FlowLayout(FlowLayout.LEFT, 10, 10));
    String spaces = "";
    for (int i = 1; i <= 20; i++) {
      this.add(new JButton("Button #" + i + spaces));
      spaces += " ";
  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
    frame.getContentPane().add(new FlowLayoutPane(), BorderLayout.CENTER);
    frame.setSize(600, 400);
    frame.setVisible(true);
}[2]. FlowLayoutPaneCall.java
import java.awt.*;
import javax.swing.*;
public class FlowLayoutPaneCall extends JPanel
     FlowLayoutPane sftp = new FlowLayoutPane();
    public FlowLayoutPaneCall()
           add(sftp);
     public static void main(String[] args) {
          FlowLayoutPaneCall dm = new FlowLayoutPaneCall();
          JFrame f = new JFrame();
            f.setSize(400,400);
             f.setLocation(200,200);
             f.setVisible(true);
          f.getContentPane().add(dm, BorderLayout.CENTER);
          f.pack();
          f.setVisible(true);
Thanks so much!!!

Answer 1

it works, thanks, but If I add following code to add one more panel etc, It still not work, see below,
after call, the layout of 20 buttons in main program
is different from the one of original, how can I keep them same for this new updating??
Thanks
import java.awt.*;
import javax.swing.*;
public class FLPCall extends JPanel {
     FlowLayoutPane sftp = new FlowLayoutPane();
    public FLPCall() {
        super(new BorderLayout());
        JLabel jl =new  JLabel("My New Test Start here");
        JPanel panel =new  JPanel();
        panel.add(sftp);
        add(jl, BorderLayout.NORTH);
        add(panel, BorderLayout.CENTER);
    public static void main(String[] args) {
        FLPCall dm = new FLPCall();
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(dm, BorderLayout.CENTER);
        f.setSize(400,400);
        f.setLocation(200,200);
//        f.pack();
        f.setVisible(true);