/** * 二叉树节点类 * */class Node<T extends Comparable> {  public Node(T data){    this.data=http://www.mamicode.com/data;  }    T data;  Node<T> left;  Node<T> right;}/** * 二叉树类*/public class BinaryTree<T extends Comparable> {  /**   * 根節點   */  private Node<T> root;  /**   * 插入一個值   * @param value   */  public void insert(T value) {    Node<T> node = new Node<T>(value);    if (root == null) {      root = node;    } else {      Node<T> curr = root;      Node<T> parrent;      while (true) {        parrent = curr;        if (value.compareTo(curr.data) >= 0) {          curr = curr.right;          if (curr == null) {            parrent.right=node;            return;          }        } else {          curr = curr.left;          if (curr == null) {            parrent.left=node;            return;          }        }      }    }  }  /**   * 尋找一個值對應的節點   * @param value   * @return   */  public Node<T> find(T value) {    Node<T> curr = root;    while (curr.data.equals(value) == false) {      if (value.compareTo(curr.data) > 0) {        curr = curr.right;      } else {        curr = curr.left;      }      if (curr == null) {        return null;      }    }    return curr;  }  /**   * 輸出   *   */  public void printAll() {    System.out.println("--------------先序遍历------------------");    preOrder(root);    System.out.println("--------------中序遍历------------------");    inorder(root);    System.out.println("--------------后序遍历------------------");    postOrder(root);  }    /**   * 先序遍歷   * @param node   */  private void preOrder(Node<T> node) {    if (node != null) {      System.out.println(node.data);      preOrder(node.left);            preOrder(node.right);    }  }  /**   * 中序遍歷   * @param node   */  private void inorder(Node<T> node) {    if (node != null) {      inorder(node.left);      System.out.println(node.data);      inorder(node.right);    }  }    /**   * 后序遍歷   * @param node   */  private void postOrder(Node<T> node) {    if (node != null) {      postOrder(node.left);           postOrder(node.right);      System.out.println(node.data);    }  }  public static void main(String[] args) {        Integer[] arr={31,25,47,42,50};        // 以數組2為基礎創建二叉樹    BinaryTree<Integer> tree1=new BinaryTree<Integer>();       for(Integer i:arr){      tree1.insert(i);    }        tree1.printAll();            String[] arr02={"Ceaser","Andy","Martin","Bill","Felex","Fowler","Green","Alice","Gates"};        // 以數組2為基礎創建二叉樹    BinaryTree<String> tree=new BinaryTree<String>();       for(String str:arr02){      tree.insert(str);    }        tree.printAll();        // 將在二叉樹中不存在的元素放入鏈錶    String[] arr01={"Andy","Bill","Cindy","Douglas","Felex","Green"};    List<String> ls=new ArrayList<String>();        for(String str:arr01){      if(tree.find(str)==null){        ls.add(str);      }    }        // 輸出    System.out.println("--------------二叉樹中不存在的元素有------");    for(String str:ls){      System.out.println(str);    }  }}