【仅贴代码及测试结果】

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

class Tree
     
      {    E element;    Tree
      
        lChild;    Tree
       
         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
        
          n1 = new Tree
         
          (1);        Tree
          
            n2 = new Tree
           
            (2); Tree
            
              n3 = new Tree
             
              (3); Tree
              
                n4 = new Tree
               
                (4); Tree
                
                  n5 = new Tree
                 
                  (5); Tree
                  
                    n6 = new Tree
                   
                    (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 
                    
                      void firstOrder(Tree
                     
                       root){ if(root!=null){ System.out.print(root.element+" "); firstOrder(root.lChild); firstOrder(root.rChild); } } public static 
                      
                        void lastOrder(Tree
                       
                         root){ if(root!=null){ lastOrder(root.lChild); lastOrder(root.rChild); System.out.print(root.element+" "); } } public static 
                        
                          void midOrder(Tree
                         
                           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