創建節點后，我想獲取一個 MyNodeUserObject，以便稍后調用 getFlops() 方法。但我無法將 userobject 轉換為 MyNodeUserObject。創建節點：MyNodeUserObject userObject = new MyNodeUserObject("aaa","AA-10");DefaultMutableTreeNode node = new DefaultMutableTreeNode(userObject);public static void visitAllNodes(DefaultMutableTreeNode node, JTree tree) {    //java.lang.ClassCastException: java.lang.String cannot be cast to MyNodeUserObject    MyNodeUserObject nodeInfo = (MyNodeUserObject) node.getUserObject();MyNodeUserObject.classpublic final class MyNodeUserObject{    private static final long serialVersionUID = 1L;    private final String flops;    private final String nodeName;    public MyNodeUserObject(String nodeName, String flops) {        this.flops = flops;        this.nodeName = nodeName;    }    public String getFlops() {        return flops;    }    public String getNodeName() {        return nodeName;    }    @Override    public String toString() {        return nodeName;    }tree.txt 的內容：節點名稱；IsFolder(true/false);Parent;Flopsmy range;true; ;a;false;我的范圍;AA,AKs,AKob;false;我的范圍;66,55,44,33,22c;false;我的范圍;JJ,TT,99,88