JFileChooser java example

Problem:

Create java gui app that allows the user to pick picture
and text files only and displays them respectively.
Solution:

import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;

import javax.swing.JEditorPane;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JScrollPane;
import javax.swing.filechooser.FileFilter;

public class JFileChooserapp extends JFrame {

 
 private JMenuBar bar;
 private JMenu fileMenu;
 private JMenuItem openMenuItem;
 private JEditorPane contentArea;
 private JScrollPane scrollPane;
 private File selectedFile;
 private String[] okExtensions = {"png", "gif", "tiff", "jpg", "txt"};
 
 public JFileChooserapp() {
  super("JFileChooser Demo");
  
  bar = new JMenuBar();
  setJMenuBar(bar);
  
  fileMenu = new JMenu("File");
  fileMenu.setMnemonic('f');
  
  openMenuItem = new JMenuItem("Open");
  openMenuItem.setMnemonic('o');
  openMenuItem.addActionListener(new ActionListener() {
   
   @Override 
   public void actionPerformed(ActionEvent e) {
    selectedFile = getFile();
    if(selectedFile !=null)
     displayFile(selectedFile);
   }

  });
  
  fileMenu.add(openMenuItem);
  bar.add(fileMenu);
  setJMenuBar(bar);
  
  contentArea = new JEditorPane();
  contentArea.setEditable(false);
  scrollPane = new JScrollPane(contentArea);
  
  Container contentPane = getContentPane();
  contentPane.add(scrollPane);
  
  setExtendedState(JFrame.MAXIMIZED_BOTH);
  setVisible(true);
  
  
 }
 
 private File getFile() {
  
  File output = null;
  
  JFileChooser fileChooser = new JFileChooser();
  fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
  fileChooser.setFileFilter(new FileFilter() {

   @Override
   public String getDescription() {
   String description = "";
   for (String ext : okExtensions) 
    description += "*." + ext + " ";
   return description;
   }
   
   @Override
   public boolean accept(File f) {
    for(String ext: okExtensions)  
     if (f.getName().toLowerCase().endsWith(ext)) 
     return true;
    return false;
   }

   
  
  });
  
  int result = fileChooser.showOpenDialog(this);
  if (result == JFileChooser.APPROVE_OPTION) {
    output = fileChooser.getSelectedFile();
    if ( output == null || !output.exists()) output = null;
  }
  return output;
  }

 private void displayFile(File file) {
 
  String fileName = file.getName();
  int lastIndexOfDot = fileName.lastIndexOf('.');
  String extension  = fileName.substring(lastIndexOfDot+1);
  boolean isImage = true;
  if (extension.equalsIgnoreCase("txt")) isImage= false;
  
  URL fileUrl = null;
  try {
   fileUrl = file.toURI().toURL();
  } catch (MalformedURLException e) {
   return;
  }
  
  if (isImage) {
   contentArea.setContentType("text/html");
   contentArea.setText("<html><title>Image</title><img src=" + 
   fileUrl + " /></html>");
   
  } else {
   try {
    contentArea.setContentType("text/plain");
    contentArea.setPage(fileUrl);
   } catch (IOException e) {
    return;
   }
  }
  
  
  
 }
 
 
 
 public static void main(String[] args) {
  JFileChooserapp demo = new JFileChooserapp();
  demo.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  
 }
 
 
 
 
 
 
 
 
 
 
 
 
 
}
JFileChooser java example

Problem:

Solution:

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