API文档中一个问题

Question

class Hyperactive implements HyperlinkListener {
 
         public void hyperlinkUpdate(HyperlinkEvent e) {
             if (e.getEventType() == HyperlinkEvent.EventType.ACTIVATED) {
                 JEditorPane pane = (JEditorPane) e.getSource();
                 if (e instanceof HTMLFrameHyperlinkEvent) {
                     HTMLFrameHyperlinkEvent  evt = (HTMLFrameHyperlinkEvent)e;
                     HTMLDocument doc = (HTMLDocument)pane.getDocument();
                     doc.processHTMLFrameHyperlinkEvent(evt);
                 } else {
                     try {
                         pane.setPage(e.getURL());
                     } catch (Throwable t) {
                         t.printStackTrace();
                     }
                 }
             }
         }
     }
中                 if (e instanceof HTMLFrameHyperlinkEvent) {
                     HTMLFrameHyperlinkEvent  evt = (HTMLFrameHyperlinkEvent)e;
                     HTMLDocument doc = (HTMLDocument)pane.getDocument();
                     doc.processHTMLFrameHyperlinkEvent(evt);是都是什么意思呀？看文档也没太看懂如何实现的。希望有高人依次解答

Answer 1

对HTML文档的操作啊，LZ如果对HTML比较熟悉的话就很容易理解了。