二叉树遍历

这里写的是最简单的二叉树遍历，最简单的定义，为的是清晰，一目了然。

首先：Tree.java--》

package 二叉树遍历;
@SuppressWarnings("all")
public class Tree {
    //定义根值
    private String value;
    private Tree left;
    private Tree right;
    /** 
     * 功能：定义一个二叉树，然后进行3种方式的遍历. 
     * 构造的二叉树： 
     *               1   
     *             /    
     *            2     3 
     *           /    /  
     *          4   5  6  7 
     *         /  
     *        8   9  
     *  先序遍历：DLR 
     *  1 2 4 8 9 5 3 6 7 
     *  中序遍历：LDR 
     *  8 4 9 2 5 1 6 3 7 
     *  后序遍历：LRD 
     *  8 9 4 5 2 6 7 3 1   
     */  
    public Tree createTree() {
        //定义最上层根节点
        this.value="1";
        
        //定义最上层根节点-->左子树
        this.left=new Tree();
        Tree left1=this.left;
            //深度2
            left1.value="2";
            left1.left=new Tree();
            left1.right=new Tree();

                //深度3
                Tree left1_left2=left1.left;
                Tree left1_right2=left1.right;
                
                left1_left2.value="4";
                left1_right2.value="5";
                
                left1_left2.left=new Tree();
                left1_left2.right=new Tree();
                
                    //深度4
                    Tree left2_left3=left1_left2.left;  
                    Tree left2_right3=left1_left2.right;
                    left2_left3.value="8";
                    left2_right3.value="9";
                    
        //定义最上层根节点-->右子树
        this.right=new Tree();
        Tree right1=this.right;

                //深度2
                right1.value="3";
                right1.left=new Tree();
                right1.right=new Tree();
                    //深度3
                    Tree right1_left1=right1.left;
                    Tree right1_right1=right1.right;
                    right1_left1.value="6";
                    right1_right1.value="7";
        return this;
    }
    
    //前序遍历
    public void beforeFindData(Tree tree) {
        if(tree!=null) {
            System.out.print(tree.value+" ");
            beforeFindData(tree.left);
            beforeFindData(tree.right);
        }else {
            return;
        }
        
    }
    //中序遍历
    public void contreFindData(Tree tree) {
        if(tree!=null) {
            contreFindData(tree.left);
            System.out.print(tree.value+" ");
            contreFindData(tree.right);
        }else {
            return;
        }
    }
    //后序遍历
    public void afterFindData(Tree tree) {
        if(tree!=null) {
            afterFindData(tree.left);
            afterFindData(tree.right);
            System.out.print(tree.value+" ");
        }else {
            return;
        }
    }
   
}

测试用例：TreeTest.java-->

package 二叉树遍历;

public class TreeTest {
     public static void main(String args[]) {
         Tree t=new Tree().createTree();
         System.out.print("前序遍历:-->");
         t.beforeFindData(t);
         System.out.println("");
         System.out.print("中序遍历:-->");
         t.contreFindData(t);
         System.out.println("");
         System.out.print("后序遍历:-->");
         t.afterFindData(t);
         System.out.println("");
     }
}

结果：