Updating Layout of Panel after changing label icon - swing

Question

I have created a project that will download the thumbnails of the images from a ftp server and display it in a panel using JLabel.
The images are being displayed but the layout of the panel only works if i call the panel once more (i.e using a button on the frame) then the layout corrects itself automatically. What am i doing wrong? Here is the code
EDIT- Updated the code with sscce
1. sscce.java
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
/**
*
* #author Rohn
*/
public class Sscce implements Interface{
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
JFrame frame=new JFrame();
frame.setVisible(true);
//frame.add(sci.);
Container c=frame.getContentPane();
JButton button=new JButton("Recall ShowCategoryImagesFunction");
button.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
sci.ShowCategoryImagesFunction("\\Nature\\Black And White"); //for testing purpose only
// if button is pressed then we get right layout and image load
}
});
c.setLayout(new FlowLayout());
c.add(button);
c.add(sci.ShowCategoryImagesFunction("\\Nature\\Black And White")); // default path for image load for first time
// problem in correctly loading images and text with layout
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
2. ShowCategoryImages.java
package sscce;
import it.sauronsoftware.ftp4j.FTPClient;
import it.sauronsoftware.ftp4j.FTPFile;
import java.awt.FlowLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.io.File;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingConstants;
public class ShowCategoryImages{
//FTPClient client=null;
JPanel panel=new JPanel();
JLabel label=new JLabel();
FTPClient client=new FTPConnection().FTPConnection();
FTPFile[] list;
File thumbnails;
File[] files;
ImageIcon icon;
public JPanel ShowCategoryImagesFunction(String path){
// delete all the components on reload
if(panel.getComponents().length>0){
System.out.println(panel.getComponents().length);
panel.removeAll();
panel.revalidate();
panel.repaint();
}
//panel.setLayout(new GridLayout(0,4,2,2));
//panel.setLayout(new BoxLayout(panel,BoxLayout.X_AXIS));
panel.setLayout(new FlowLayout());
panel.revalidate();
panel.repaint();
panel.updateUI();
try{
//images in /wallpapers/nature/black and white/thumb
client.changeDirectory("\\Wallpapers"+path+"\\thumb"); //path of thumbnails
//temporary folder for holding images
thumbnails=new File("Thumbnails");
list=client.list();
if(thumbnails.exists()){
files = thumbnails.listFiles();
if(files!=null) { //some JVMs return null for empty dirs
for(File f: files) {
f.delete();
}
}
}
else
thumbnails.mkdir();
for(int i=0;i<list.length;i++){
System.out.println("running");
icon=new ImageIcon(thumbnails.getAbsolutePath()+"\\"+list[i].getName());
icon.getImage().flush();
client.download(client.currentDirectory()+"\\"+list[i].getName(), new java.io.File(thumbnails.getAbsolutePath()+"\\"+list[i].getName()));
label=new JLabel(list[i].getName());
label.setIcon(icon);
label.setVerticalTextPosition(SwingConstants.BOTTOM);
label.setHorizontalTextPosition(SwingConstants.CENTER);
panel.add(label);
panel.revalidate();
panel.repaint();
label.addMouseListener(new MouseAdapter(){
public void mousePressed(MouseEvent e){
JLabel la=(JLabel)e.getSource();
System.out.println(la.getIcon());
}
});
}
//client.disconnect(true);
}catch(Exception e){
System.out.println(e.getMessage());
}
return panel;
}
}
3. FTPConnection.java
import it.sauronsoftware.ftp4j.FTPClient;
public class FTPConnection {
//ftp connection on local host
public static FTPClient FTPConnection(){
String ftphost="127.0.0.1";
String ftpuser="newuser";
String ftppassword="wampp";
int ftpport=21;
FTPClient client=new FTPClient();
try{
if(client.isConnected()==true){
client.disconnect(true);
};
client.connect(ftphost, ftpport);
client.login(ftpuser, ftppassword);
}
catch(Exception e){
System.out.println(e.getMessage());
}
return client;
}
}

Answer 1

not entirely sure what you mean with not layout, but your code is missing a revalidate/repaint after adding the labels:
// adding all labels
forEach (thumb....) {
JLabel label = new JLabel(thumb);
panel.add(label);
}
panel.revalidate();
panel.repaint();