初学菜鸟的学习日记——二叉树（JAVA）

这几天看了看JAVA数据结构，其中链表之类的结构之前看过JDK源码，但是树之类的是第一次接触。最近封闭开发挺忙的，抽了点时间自己实现一个二叉树，实现了最基本的增删改查和截取，挺简陋的，冗余代码比较多。而且有的地方设计的不太合理。暂且记下这些，晚上再好好改改。不怕被喷，就怕不懂装懂。骚年，Go ahead!!!

 

package duty;

import java.util.TreeMap;

/**
 * @author Administrator
 *
 * @param 
 * @param 
 */
public class Tree implements Cloneable{
 public static final String DEFAULT_CLASS_NAME = Integer.class.getName();
 private static final Integer DEFAULT_KEY = 0;
 private static final Object DEFAULT_VALUE = null;
 private Node root;
 private Node currentNode;
 private transient int size = 0;
 
 public Tree(){}
 
 public Tree(Class type){
  try {
   K obj = (K) type.newInstance();
   init((Comparable) obj,null);
  } catch (InstantiationException e) {
   e.printStackTrace();
  } catch (IllegalAccessException e) {
   e.printStackTrace();
  }
 }
 
 @SuppressWarnings({ "rawtypes", "unchecked" })
 public Tree(Tree tree){
  if(tree==null||tree.root==null){
   return;
  }
  root = (Node) tree.root;
  currentNode = root;
  size = tree.size();
 }
 
 Tree(Node node){
  this.root = node;
 }
 
 public Tree(boolean forceInit){
  if(!forceInit){
   return;
  }
  init((Comparable) DEFAULT_KEY,(K) DEFAULT_VALUE);
 }
 
 public Tree(Comparable key,K value){
  init(key,value);
 }
 
 
 private void init(Comparable key,K value){
  root = new Node(key,value);
  currentNode = root;
 }
 
 public K put(Comparable key,K value) throws IllegalArgumentException{
  if(key==null){
   throw new IllegalArgumentException("The key of tree can't be null...");
  }
  size ++;
  if(root == null){
   root = new Node(key,value);
   return null;
  }
  K oldValue = checkPosition(key,value);
  currentNode = root;
  return oldValue;
 }

 /**
  * 遍历插入
  * @param key
  * @param value
  * @return
  */
 @SuppressWarnings("unchecked")
 private K checkPosition(Comparable key,K value){
  if(key.compareTo((T) currentNode.key)==0){//如果找到一样的节点，返回初始值
   K oldValue = currentNode.value;
   currentNode.value = value;
   size--;
   return oldValue;
  }else if(key.compareTo((T)currentNode.key)<0){//如果小于当前节点，左转寻径
   if(currentNode.leftChild == null){
    currentNode.leftChild = new Node(key,value);
    currentNode.leftChild.parent = currentNode;
    return null;
   }
   currentNode = currentNode.leftChild;
  }else{
   if(currentNode.rigthChild == null){
    currentNode.rigthChild = new Node(key,value);
    currentNode.rigthChild.parent = currentNode;
    return null;
   }
   currentNode = currentNode.rigthChild;
  }
  return checkPosition(key,value);
 }
 
 public K get(Comparable key){
  if(key == null){
   return null;
  }
  K value = checkGet(key);
  currentNode = root;
  return value;
 }
 
 /**
  * @param key
  * @return
  */
 @SuppressWarnings("unchecked")
 private K checkGet(Comparable key){
  if(key.compareTo(currentNode.key)==0){
   return currentNode.value;
  }else if(key.compareTo(currentNode.key)<0){
   if(currentNode.leftChild==null){
    return null;
   }
   currentNode = currentNode.leftChild;
  }else if(key.compareTo(currentNode.key)>0){
   if(currentNode.rigthChild==null){
    return null;
   }
   currentNode = currentNode.rigthChild;
  }
  return checkGet(key);
 }
 
 public K remove(Comparable key){
  K obj = checkRemove(key);
  currentNode = root;
  size--;
  return obj;
 }
 
 /**
  * 递归遍历树
  * @param key
  * @return
  */
 private K checkRemove(Comparable key){
  if(key.compareTo(currentNode.key)==0){
   K value = currentNode.value;
   if(currentNode == root){
    clear();
    return value;
   }
   Node parent = currentNode.parent;
   int compare =currentNode.key.compareTo((T) parent.key);
   if(currentNode.leftChild==null&¤tNode.rigthChild==null){
    if(compare<0)
     parent.leftChild=null;
    else
     parent.rigthChild=null;
   }else if(currentNode.leftChild!=null&¤tNode.rigthChild==null){
    if(compare<0)
     parent.leftChild = currentNode.leftChild;
    else
     parent.rigthChild = currentNode.leftChild;
   }else if(currentNode.rigthChild!=null&¤tNode.leftChild==null){
    if(compare<0)
     parent.leftChild = currentNode.rigthChild;
    else
     parent.rigthChild = currentNode.rigthChild;
    
    //忘了这里是怎么规定的了。。。就先优先最大或最小吧
   }else if(currentNode.rigthChild!=null && currentNode.rigthChild!=null){
    if(compare<0){
     parent.leftChild = currentNode.leftChild;//断开当前节点，接上下面的节点
     currentNode.leftChild.rigthChild = currentNode.rigthChild;
    }else{
     parent.rigthChild = currentNode.rigthChild;
     currentNode.rigthChild.leftChild = currentNode.leftChild;
    }
   }
   return value;
  }else if(key.compareTo(currentNode.key)<0){
   if(currentNode.leftChild==null){
    return null;
   }
   currentNode = currentNode.leftChild;
  }else if(key.compareTo(currentNode.key)>0){
   if(currentNode.rigthChild==null){
    return null;
   }
   currentNode = currentNode.rigthChild;
  }
  return checkRemove(key);
 }
 
 public void clear(){
  root = null;
 }
 
 public int size(){
  return size;
 }
 
 public Tree subTree(Comparable key){
  if(key==null)
   return null;
  Tree tree =checkSubTree(key);
  currentNode = root;
  return tree;
 }
 
 @SuppressWarnings("rawtypes")
 public Tree checkSubTree(Comparable key){
  if(key.compareTo(currentNode.key)==0){
   Node store = root;
   root = currentNode;
   Tree tree;
   try {
    tree = (Tree) this.clone();
    root = store;
    return tree;
   } catch (CloneNotSupportedException e) {
    e.printStackTrace();
   }
  }else if(key.compareTo(currentNode.key)<0){
   if(currentNode.leftChild==null){
    return null;
   }
   currentNode = currentNode.leftChild;
  }else if(key.compareTo(currentNode.key)>0){
   if(currentNode.rigthChild==null){
    return null;
   }
   currentNode = currentNode.rigthChild;
  }
  return checkSubTree(key);
 }
 
 @Override
 public String toString() {
  return "Tree [root=" + root + "]";
 }

 /**
  * @author zhq
  * 树节点类
  *
  */
 private class Node{
  Node leftChild; //左节点
  Node rigthChild;
  Node parent;//父节点
  private Comparable key;
  private K value;
  public Node(Comparable key,K value){
   this.key = key;
   this.value = value;
  }
  @Override
  public String toString() {
   return "Node [leftChild=" + leftChild + ", rigthChild="
     + rigthChild + ", key=" + key + ", value=" + value + "]";
  }
  
 }
 public static void main(String[] args) {
  Tree tree= new Tree("2",2);
  tree.put("1", 1);
  tree.put("6", 32);
  tree.put("1a", 3);
  Tree tree1 = tree.subTree("1");
  System.out.println(tree);
  System.out.println(tree1);
  tree.remove("1a");
  System.out.println(tree);
  System.out.println(tree.get("1"));
  System.out.println(tree.get("1a"));
  System.out.println(tree.get("555"));
  tree.clear();
  System.out.println(tree.get("6"));
  
 }
}