private void buildUI() {
setLayout(new BorderLayout());
java.util.List<String> extensions = (java.util.List<String>) Arrays.asList((new String[]{"pprj", "owl" , "rdfs", "rdf"}));
fileField = new FileField("Select file", null, new ExtensionFilter(extensions.iterator(), "Files"));
JPanel filePanel = new JPanel(new BorderLayout());
filePanel.add(fileField, BorderLayout.CENTER);
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new BoxLayout(buttonPanel, BoxLayout.Y_AXIS));
JButton button = new JButton(getLoadAction());