二叉树遍历Java实现

 

【仅贴代码及测试结果】

-------------------BinaryTree.java------------------------------

class Tree<E>{
    E element;
    Tree<E> lChild;
    Tree<E> rChild;
    public Tree(E e){
        element = e;
    }
}
public class BinaryTree {

    /**
     * 树形如下：
     *         1
     *     / \
     *    2   3
     *    \   / \
     *     4  5  6
     */    
    public static void main(String[] args) {

        Tree<Integer> n1 = new Tree<Integer>(1);
        Tree<Integer> n2 = new Tree<Integer>(2);
        Tree<Integer> n3 = new Tree<Integer>(3);
        Tree<Integer> n4 = new Tree<Integer>(4);
        Tree<Integer> n5 = new Tree<Integer>(5);
        Tree<Integer> n6 = new Tree<Integer>(6);
        System.out.println("Construct the tree...");
        n2.rChild=n4;
        n3.lChild=n5;
        n3.rChild=n6;
        n1.lChild=n2;
        n1.rChild=n3;
        
        System.out.println("打印先序遍历结果：");
        firstOrder(n1);
        System.out.println("\n打印中序遍历结果：");
        midOrder(n1);
        System.out.println("\n打印后序遍历结果：");
        lastOrder(n1);
    }
    
    public static <E> void firstOrder(Tree<E> root){
        if(root!=null){
            System.out.print(root.element+" ");
            firstOrder(root.lChild);
            firstOrder(root.rChild);
        }
    }
    public static <E> void lastOrder(Tree<E> root){
        if(root!=null){
            lastOrder(root.lChild);
            lastOrder(root.rChild);
            System.out.print(root.element+" ");
        }
    }
    public static <E> void midOrder(Tree<E> root){
        if(root!=null){
            midOrder(root.lChild);
            System.out.print(root.element+" ");
            midOrder(root.rChild);
        }
    }

}

输出结果：

Construct the tree...
打印先序遍历结果：
1 2 4 3 5 6 
打印中序遍历结果：
2 4 1 5 3 6 
打印后序遍历结果：
4 2 5 6 3 1