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POTree of Node<T> explaination
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copied!<p>Don't know if i am allowed to do this according to the rules of the site... but i will take my chance... please bear with me, i am only a student... :-)</p> <p>I have a college assignment... I am having hard time understanding what the classes should do... i have gone to my teacher on three different occasions and the answer i got from him didn't help at all. Anyway the assignment details goes as follow...</p> <p>Create a class called <code>Tree</code> that acts as a container for nodes. The tree class should support the following methods.</p> <blockquote> <p><strong>public void add(Node parent, Node child){}</strong> -- Adds a new child node to the parent node</p> <p><strong>public void removeChild(Nodeparent, Node child){}</strong> -- Removes a child node from a parent.</p> <p><strong>public Node getRootNode(){}</strong> -- Returns the root of the tree</p> <p><strong>public void setRoot(Node root){}</strong> -- Sets the root node of the tree</p> <p><strong>public boolean contains(T data){}</strong> -- Searches the tree for a given type</p> <p><strong>public void dfs(Node child){}</strong> -- Performs a depth-first-search of the tree and outputs each node (indented)</p> <p><strong>public void bfs(Node child){}</strong> -- Performs a breadth-first-search of the tree and outputs each node (indented)</p> </blockquote> <ol> <li>The tree class should be parameterized to handle a generic type T, allowing trees of strings, files etc... to be created, e.g. <code>Tree<String> tree = new Tree<String>()</code></li> <li>The tree class should implement the tree structure using an adjacency list and be defined in the following way: <code>Map<Node<T>, List<Node<T>>> tree = new HashMap<Node<T>, List<Node<T>>();</code></li> </ol> <p>The node class should also be parameterized to handle a generic type T and expose several methods...</p> <p>Now i have written my Node class which works fine... and to be honest, i was sure that i have written a Node class which is creating a Tree. but after reading the Tree class description i am confused. What i should store in the tree Map. I am having hard time visualizing the whole thing.</p> <p>Perhaps someone can explain what teacher wants and put me in the right direction. I am <strong>NOT</strong> looking for the code itself... just want to understand what i am suppose to do.</p> <p>My Node Class</p> <pre><code>public class Node<T> { private Node<T> root; // a T type variable to store the root of the list private Node<T> parent; // a T type variable to store the parent of the list private T child; private List<Node<T>> children = new ArrayList<Node<T>>(); // a T type list to store the children of the list // default constructor public Node(T child) { setParent(null); setRoot(null); setItem(child); } // constructor overloading to set the parent public Node(Node<T> parent) { this.setParent(parent); //this.addChild(parent); } // constructor overloading to set the parent of the list public Node(Node<T> parent, Node<T> child) { this(parent); this.children.add(child); } /** * This method doesn't return anything and takes a parameter of * the object type you are trying to store in the node * * @param Obj an object * @param **/ public void addChild(Node<T> child) { child.root = null; child.setParent((Node<T>)this); this.children.add(child); // add this child to the list } public void removeChild(Node<T> child) { this.children.remove(child); // remove this child from the list } public Node<T> getRoot() { return root; } public boolean isRoot() { // check to see if the root is null if yes then return true else return false return this.root != null; } public void setRoot(Node<T> root) { this.root = root; } public Node<T> getParent() { return parent; } public void setParent(Node<T> parent) { this.parent = parent; } public T getItem() { return child; } public void setItem(T child) { this.child = child; } public boolean hasChildren() { return this.children.size()>0; } @SuppressWarnings("unchecked") public Node<T>[] children() { return (Node<T>[]) children.toArray(new Node[children.size()]); } @SuppressWarnings({ "unchecked"}) public Node<T>[] getSiblings() { if(this.isRoot()!=false && parent==null) { System.out.println("this is root or there are no siblings"); return null; } else{ List<Node<T>> siblings = new ArrayList<Node<T>>((Collection<? extends Node<T>>) Arrays.asList(new Node[this.parent.children.size()])); Collections.copy(siblings, this.parent.children); siblings.remove(this); return siblings.toArray(new Node[siblings.size()]); } } } </code></pre>

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