java实现二叉树前序、中序、后序递归遍历详解步骤和图解

二叉树遍历概述

前序遍历：根——>左子树——>右子树

中序遍历：左子树——>根——>右子树

后序遍历：左子树——>右子树——>根

二叉树数据结构：链表

实现的二叉树遍历对象

前序遍历详细图解：后序和中序大致相同就不列举了

二叉树节点类

 
public class Node {

	Object value; //结点值
	Node leftChild;//左子树的引用
	Node rightChild;//右子树的引用
	
	
	public Node(Object value) {
		super();
		this.value = value;
	}

	public Node(Object value, Node leftChild, Node rightChild) {
		super();
		this.value = value;
		this.leftChild = leftChild;
		this.rightChild = rightChild;
	}

	@Override
	public String toString() {
		return "Node [value=" + value + ", leftChild=" + leftChild
				+ ", rightChild=" + rightChild + "]";
	}
}

二叉树遍历实现类

//前序
public void preOrderTraverse() {
		this.preOrderTraverse(root);
		
	}
	public void preOrderTraverse(Node node) {
		if (node!=null) {
			System.out.print(node.value+" ");
			this.preOrderTraverse(node.leftChild);
		    this.preOrderTraverse(node.rightChild);
		}
	}

//中序

	public void inOrderTraverse() {
		
		this.inOrderTraverse(root);
	}
	
	public void inOrderTraverse(Node node) {
		if (node!=null) {
		
			this.preOrderTraverse(node.leftChild);
			System.out.print(node.value+" ");
		    this.preOrderTraverse(node.rightChild);
		}
		
	}
	
//后序
	public void postOrderTraverse() {
      this.postOrderTraverse(root);
		
	}
	public void postOrderTraverse(Node node) {
		if (node!=null) {
			this.preOrderTraverse(node.leftChild);
		    this.preOrderTraverse(node.rightChild);
		    System.out.print(node.value+" ");
		}
	}

二叉树运行类

public class MyTest {

	public static void main(String[] args) {
		//创建一个二叉树
		Node node5 = new Node(5, null, null);
		Node node4 = new Node(4, null, node5);
		
		Node node3 = new Node(3, null, null);
		Node node7 = new Node(7, null, null);
		Node node6 = new Node(6, null, node7);
		
		Node node2 = new Node(2, node3, node6);
		
		Node node1 = new Node(1,node4,node2);
		
		BinaryTree  btree = new LinkedBinaryTree(node1);
		//BinaryTree  btree = new LinkedBinaryTree();
		
		//判断二叉树是否为空
		System.out.println(btree.isEmpty());
		
		System.out.println("先序遍历");
		btree.preOrderTraverse();
		System.out.println();
		System.out.println("中序遍历");
		btree.inOrderTraverse();
		System.out.println();
		System.out.println("后序遍历");
		btree.postOrderTraverse();
	}

}

结果