public void deleteLearnCategories() { ArrayList<Category> learnCategories = learnGraph.getCategories(); for (Category c : learnCategories) { Nodemapper n = brain.findNode(c); System.out.println("Found node " + n + " for " + c.inputThatTopic()); if (n != null) n.category = null; } learnGraph = new Graphmaster(this); }