import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;
import java.io.IOException;
import javax.swing.JFileChooser;
public class Main {
final static JFileChooser fc = new JFileChooser("/");
public static void main(String[] args) throws IOException {
fc.setMultiSelectionEnabled(true);
fc.addPropertyChangeListener(new ChangeListener());
fc.showOpenDialog(null);
}
private static class ChangeListener implements PropertyChangeListener {
@Override
public void propertyChange(PropertyChangeEvent evt) {
if (JFileChooser.SELECTED_FILES_CHANGED_PROPERTY.equals(evt
.getPropertyName())) {
File[] selectedFiles = fc.getSelectedFiles();
File[] allowedFiles = new File[2];
if (selectedFiles.length > 2) {
allowedFiles[0] = selectedFiles[1];
allowedFiles[1] = selectedFiles[0];
fc.setSelectedFiles(allowedFiles);
}
}
}
}
}