java程序实现：如何构建一个二叉树。

package com.wp;

//import java.util.*;

public class BinaryTreeNode {

    int m_nValue;
    BinaryTreeNode       m_pLeft;
    BinaryTreeNode       m_pRight;


   public static BinaryTreeNode CreateBinaryTreeNode(int value)
    {
        BinaryTreeNode pNode = new BinaryTreeNode();
        pNode.m_nValue = value;
        pNode.m_pLeft = null;
        pNode.m_pRight = null;

        return pNode;
    }

  public static void ConnectTreeNodes(BinaryTreeNode pParent, BinaryTreeNode pLeft, BinaryTreeNode pRight)
   {
       if(pParent != null)
       {
           pParent.m_pLeft = pLeft;
           pParent.m_pRight = pRight;
       }
   }


  //先序遍历二叉树
   public static void InorderTree(BinaryTreeNode pRoot)
   {

       if(pRoot != null)
       {

         System.out.print(pRoot.m_nValue);

           if(pRoot.m_pLeft != null)
               InorderTree(pRoot.m_pLeft);

           if(pRoot.m_pRight != null)
               InorderTree(pRoot.m_pRight);
       }
   }


//完全二叉树
//    1
///      \
//2        3
///\       / \
//4  5     6   7
   public static void test1(){

       BinaryTreeNode pNode1 = CreateBinaryTreeNode(1);
       BinaryTreeNode pNode2 = CreateBinaryTreeNode(2);
       BinaryTreeNode pNode3 = CreateBinaryTreeNode(3);
       BinaryTreeNode pNode4 = CreateBinaryTreeNode(4);
       BinaryTreeNode pNode5 = CreateBinaryTreeNode(5);
       BinaryTreeNode pNode6 = CreateBinaryTreeNode(6);
       BinaryTreeNode pNode7 = CreateBinaryTreeNode(7);

       ConnectTreeNodes(pNode1, pNode2, pNode3);
       ConnectTreeNodes(pNode2, pNode4, pNode5);
       ConnectTreeNodes(pNode3, pNode6, pNode7);

       InorderTree(pNode1);

   }

// 不是完全二叉树，但是平衡二叉树
// 1
///      \
//2        3
///\         \
//4  5         6
//  /
//  7

   public static void test2(){

       BinaryTreeNode pNode1 = CreateBinaryTreeNode(1);
       BinaryTreeNode pNode2 = CreateBinaryTreeNode(2);
       BinaryTreeNode pNode3 = CreateBinaryTreeNode(3);
       BinaryTreeNode pNode4 = CreateBinaryTreeNode(4);
       BinaryTreeNode pNode5 = CreateBinaryTreeNode(5);
       BinaryTreeNode pNode6 = CreateBinaryTreeNode(6);
       BinaryTreeNode pNode7 = CreateBinaryTreeNode(7);


        ConnectTreeNodes(pNode1, pNode2, pNode3);
        ConnectTreeNodes(pNode2, pNode4, pNode5);
        ConnectTreeNodes(pNode3, null, pNode6);
        ConnectTreeNodes(pNode5, pNode7, null);

        InorderTree(pNode1);

   }

//                    1
//                  /
//                2
//               /
//             3
//            /
//                     4
//                  /
//         5

 public static void test3(){

        BinaryTreeNode pNode1 = CreateBinaryTreeNode(1);
        BinaryTreeNode pNode2 = CreateBinaryTreeNode(2);
        BinaryTreeNode pNode3 = CreateBinaryTreeNode(3);
        BinaryTreeNode pNode4 = CreateBinaryTreeNode(4);
        BinaryTreeNode pNode5 = CreateBinaryTreeNode(5);

        ConnectTreeNodes(pNode1, pNode2, null);
        ConnectTreeNodes(pNode2, pNode3, null);
        ConnectTreeNodes(pNode3, pNode4, null);
        ConnectTreeNodes(pNode4, pNode5, null);

        InorderTree(pNode1);

 }
 //树中只有一个node
 public static void test4(){

        BinaryTreeNode pNode1 = CreateBinaryTreeNode(1);
        ConnectTreeNodes(pNode1, null, null);

        InorderTree(pNode1);
 }

//树中没有节点
 public static void test5(){

        InorderTree(null);
 }

   public static void main(String[] args){

      test1();
      test2();
      test3();
      test4();
      test5();
   }

}