Java创建二叉树并遍历的代码详解编程语言

Java创建二叉树并遍历的代码

public class BinaryTree { 
  
    private Node root; 
      
    /** 
     * 
     * 内部节点类 
     * @author yhh 
     */ 
    private class Node{ 
        private Node left; 
        private Node right; 
        private int data; 
        public Node(int data){ 
            this.left = null; 
            this.right = null; 
            this.data = data; 
        } 
    } 
      
    public BinaryTree(){ 
        root = null; 
    } 
      
    /** 
     * 递归创建二叉树 
     * @param node 
     * @param data 
     */ 
    public void buildTree(Node node,int data){ 
        if(root == null){ 
            root = new Node(data); 
        }else{ 
            if(data < node.data){ 
                if(node.left == null){ 
                    node.left = new Node(data); 
                }else{ 
                    buildTree(node.left,data); 
                } 
            }else{ 
                if(node.right == null){ 
                    node.right = new Node(data); 
                }else{ 
                    buildTree(node.right,data); 
                } 
            } 
        } 
    } 
      
    /** 
     * 前序遍历 
     * @param node 
     */ 
    public void preOrder(Node node){ 
        if(node != null){ 
            System.out.println(node.data); 
            preOrder(node.left); 
            preOrder(node.right); 
        } 
    } 
      
    /** 
     * 中序遍历 
     * @param node 
     */ 
    public void inOrder(Node node){ 
        if(node != null){ 
            inOrder(node.left); 
            System.out.println(node.data); 
            inOrder(node.right); 
        } 
    } 
      
    /** 
     * 后序遍历 
     * @param node 
     */ 
    public void postOrder(Node node){ 
        if(node != null){ 
            postOrder(node.left); 
            postOrder(node.right); 
            System.out.println(node.data); 
        } 
    } 
      
    public static void main(String[] args) { 
        int[] a = {2,4,12,45,21,6,111}; 
        BinaryTree bTree = new BinaryTree(); 
        for (int i = 0; i < a.length; i++) { 
            bTree.buildTree(bTree.root, a[i]); 
        } 
        bTree.preOrder(bTree.root); 
        bTree.inOrder(bTree.root); 
        bTree.postOrder(bTree.root); 
    } 
  
}