<code java>
package miw2;

import java.io.File;
import javax.swing.JFileChooser;
import javax.swing.filechooser.FileFilter;

/**
 * Prolog file chooser with filter for prolog files.
 * @author Filip
 */
public class PlFileChooser {

    /**
     * Name of the file to load.
     */
    private static String fileName;
    
    /**
     * Default constructor of prolog file chooser Dialog.
     */
    public PlFileChooser(){
        
        PlFilter filter = new PlFilter();
        JFileChooser jfc = new JFileChooser();
        jfc.setFileFilter( filter);
        if(jfc.showOpenDialog(null)== JFileChooser.APPROVE_OPTION){
            fileName = jfc.getSelectedFile().toString();
        }
    }
    
    /**
     * Prolog files' filter.
     */
    private class PlFilter extends FileFilter{

        public boolean accept(File file) {
            if(file == null)return false;
            else if(file.isDirectory())return true;
            
            return file.getName().endsWith("pl");
        }

        @Override
        public String getDescription() {
            //throw new UnsupportedOperationException("Not supported yet.");
            return "prolog files";
        }
        
    }
    
    /**
     * Return prolog file name.
     * @return file name.
     */
    public String getFile(){
        return fileName;
    }
}

</code>