Edit Question - KnowledgeHub

Title Body

My question is: if this two functions have something different? I mean I know that they return something different, but is it possible that number of elements in one would be different then in the second one. I will try to explain. I implemented TreeModel for one of my class trying to make nice view on files on the PC basing on JTree. So here is the part of it: public Object getChild(Object parent, int index) { File[] children = ((File) parent).listFiles(); if(children == null || index < 0 || index >= children.length) { return null; } File result = new MyFile(children[index]); return result; } public int getChildCount(Object parent) { //--- //String[] children = ((File)parent).list(); File[] children = ((File)parent).listFiles(); //--- if(children == null) { return 0; } return children.length; } I marked interesting code. If I changed this two lines for this commented one, sometimes I get NullPointerException after loading TreeModel: jtree.setModel(treeModel); . This uncommented does not cause any trouble. I checked the docs and it says nothing unusual including returning null by both methods. What is going on here?

Tags (comma-separated) Cancel