java二叉树的创建与遍历

public class BTreeNode {BTreeNode left,right;char element;public BTreeNode(char obj){element=obj;}}

public interface BTreeInterface {void createBTree(String str);void printBTree(BTreeNode root);void inOrder(BTreeNode root);void preOrder(BTreeNode root);void postOrder(BTreeNode root);void depthFirstSearch(BTreeNode root);void breadFirstSearch(BTreeNode root);}

public class BinaryTree implements BTreeInterface{static BTreeNode root;public BinaryTree(){root=null;}public static void main(String[] args){BinaryTree bt=new BinaryTree();String str="A(B(D,E),C(,F))";bt.createBTree(str);System.out.print("中序遍历：");bt.inOrder(root);System.out.println();    System.out.print("先序遍历：");bt.preOrder(root);System.out.println();System.out.print("后序遍历：");bt.postOrder(root);System.out.println();System.out.print("深度遍历：");bt.depthFirstSearch(root);System.out.println();System.out.print("广度遍历：");bt.breadFirstSearch(root);System.out.println();//bt.printBTree(root);}public void createBTree(String str) {// TODO Auto-generated method stubStack stack=new Stack();int k=1;BTreeNode p=null;char[] ch=str.toCharArray();for(int i=0;i<ch.length;i++){switch (ch[i]) {case ' ':break;case ',':k=2;break;case '(':k=1;stack.push(p);break;case ')':if (stack.isEmpty()) {System.out.println("输入的字符串广义表不能描述一颗二叉树，因为括号不匹配");System.exit(1);}stack.pop();break;default:p=new BTreeNode(ch[i]);if(root==null){root=p;}else{if(k==1){         ((BTreeNode)stack.peek()).left=p;   }else {     ((BTreeNode)stack.peek()).right=p;   }}break;}}}public void printBTree(BTreeNode root) {// TODO Auto-generated method stubwhile(root!=null){System.out.print(root.element);if(root.left!=null){System.out.print("(");System.out.print(root.left.element);root=root.left;}else {System.out.print(",");if(root.right!=null){System.out.print(root.right.element);    root=root.right;}}}}public void inOrder(BTreeNode root) {// TODO Auto-generated method stubif (root!=null) {inOrder(root.left);System.out.print(root.element);inOrder(root.right);}}public void preOrder(BTreeNode root) {// TODO Auto-generated method stubif(root!=null){System.out.print(root.element);preOrder(root.left);preOrder(root.right);}}public void postOrder(BTreeNode root) {// TODO Auto-generated method stubif(root!=null){preOrder(root.left);preOrder(root.right);System.out.print(root.element);}}public void depthFirstSearch(BTreeNode root) {// TODO Auto-generated method stubif(root!=null)System.out.print(root.element);if(root.left!=null)depthFirstSearch(root.left);if(root.right!=null)depthFirstSearch(root.right);}public void breadFirstSearch(BTreeNode root) {// TODO Auto-generated method stubQueue queue=new LinkedList();BTreeNode p;if(root!=null){System.out.print(root.element);queue.add(root);}while (!queue.isEmpty()) {p=(BTreeNode)queue.remove();if(p.left!=null){System.out.print(p.left.element);    queue.add(p.left);   }if(p.right!=null){System.out.print(p.right.element);    queue.add(p.right);}}}}