二叉排序树java实现

class Node{
    public int data;
    public Node left;
    public Node right;
    public Node(int data){
        this.data = data;
        this.left = null;
        this.right = null;
    }
}

/**
 * 二叉排序树，二叉查找树
 *左孩子小，右孩子大
 *
 */
public class BinaryTree {

    private Node root;
    public BinaryTree(){
        root = null;
    }

    //将数值输入构建二叉树
    public void buildTree(int[] data){
        for(int i=0;i<data.length;i++){
            insert(data[i]);
        }
    }

    public void insert(int data){
        Node newNode = new Node(data);
        if(root==null){
            root = newNode;
        }else{
            Node current = root;
            Node parent;
            while(true){//寻找插入位置
                parent = current;
                if(data<current.data){
                    current = current.left;
                    if(current==null){
                        parent.left = newNode;
                        return;
                    }
                }else{
                    current = current.right;
                    if(current==null){
                        parent.right = newNode;
                        return;
                    }
                }
            }
        }

    }

    //先序遍历
    public void preOrder(){
        this.preOrder(this.root);
    }

    public void preOrder(Node localRoot){
        if(localRoot!=null){
            System.out.print(localRoot.data + " ");
            preOrder(localRoot.left);
            preOrder(localRoot.right);
        }
    }

    //中序遍历
    public void inOrder(){
        this.inOrder(this.root);
    }
    public void inOrder(Node localRoot){
        if(localRoot!=null){
            inOrder(localRoot.left);
            System.out.print(localRoot.data + " ");
            inOrder(localRoot.right);
        }
    }

    //后序遍历
    public void postOrder(){
        this.postOrder(this.root);
    }
    public void postOrder(Node localRoot){
        if(localRoot!=null){
            postOrder(localRoot.left);
            postOrder(localRoot.right);
            System.out.print(localRoot.data + " ");

        }
    }

    //层序遍历
    public void layerTranverse() {
        if(this.root==null) {
            return;
        }
        Queue<Node> q = new LinkedList<Node>();
        q.add(this.root);
        while(!q.isEmpty()) {
            Node n = q.poll();
            System.out.println(n.data);
            System.out.println(" ");
            if(n.left!=null) {
                q.add(n.left);
            }
            if(n.right!=null) {
                q.add(n.right);
            }
        }


    } 

    public static void main(String[] args){
        int[] arr = {2,4,7,3,8,6,1};
        BinaryTree btree = new BinaryTree();
        btree.buildTree(arr);
        btree.preOrder();
        System.out.println();
        btree.inOrder();
        System.out.println();
        btree.postOrder();
    }   

}

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