求助：自定义TreeModel中无法插入节点

Question

我定义了一个TreeModel，用来生成系统文件结构树，但是无法实现插入节点，下面是我写的插入节点的方法，麻烦各位大虾给点建议，谢谢public void insertNodesInto(Object parent,Object child){//新加入的节点插在目录树的最后
File directory=(File)parent;
String str=(String)child;
File newFile=new File(directory,str);
int length=directory.list().length;
length+=1;
File[] changedChild=new File[length];for(int i=0;i<length-1;i++){
changedChild[i]=(File)getChild(directory,i);
}
changedChild[length-1]=newFile;System.out.println(changedChild[length-1].getAbsolutePath());
TreePath path=new TreePath(directory);
int[] childIndices={getChildCount(directory)-1};
//Object[] changedChild={newFile};
fireTreeNodesInsert(path,childIndices,changedChild);
}public void fireTreeNodesInsert(TreePath path,int[] indices,Object[] child){
Iterator iterator=listenerVector.iterator();
TreeModelEvent event=new TreeModelEvent(this,path,indices,child);
while(iterator.hasNext()){
TreeModelListener listener=(TreeModelListener)iterator.next();
listener.treeNodesInserted(event);
}
}