try {
UIManager.setLookAndFeel(new MetalLookAndFeel());
} catch (UnsupportedLookAndFeelException ignored) {
}
Application app = Application.getInstance();
app.load();
TreeFileChooser fileChooser = new TreeFileChooser(new JLabel(), "Select files", true);
File[] files = fileChooser.showOpenDialog();
if (files != null) {
System.out.println(Arrays.toString(files));
}