java实现数的遍历

import java.util.ArrayList;
import java.util.List;

public class Tree {

	// design node for tree

	public void printNode(TreeNode node) {

		System.out.print(node.getData());

	}

	class TreeNode {

		private String data;

		private List<TreeNode> childRen;

		public List<TreeNode> getChildRen() {
			return childRen;
		}

		public void setChildRen(List<TreeNode> childRen) {
			this.childRen = childRen;
		}

		public TreeNode(String data, List<TreeNode> childRen) {

			this.data = data;

			this.childRen = childRen;

		}

		public String getData() {

			return data;

		}

		public void setData(String data) {

			this.data = data;
		}

	}

	public static void main(String[] args) {

		Tree tree = new Tree();

		TreeNode node = tree.init();

		// 先序遍历。。。。。。。

		System.out.println("**************************");

		System.out.println("先序遍历。。。。。。。");

		tree.xianIterator(node);

		System.out.println("");

		// 中序遍历。。。。。。。

		System.out.println("**************************");

		System.out.println("中序遍历。。。。。。。");

		tree.zhongIterator(node);

		System.out.println("");

		// 后续遍历。。。。。。。

		System.out.println("**************************");

		System.out.println("后序遍历。。。。。。。");

		tree.houIterator(node);

	}

	public TreeNode init() {
		TreeNode F = new TreeNode("F", null);
		TreeNode G = new TreeNode("G", null);
		TreeNode E = new TreeNode("E", null);
		TreeNode H = new TreeNode("H", null);
		TreeNode I = new TreeNode("I", null);
		TreeNode J = new TreeNode("J", null);
		TreeNode K = new TreeNode("K", null);
		List<TreeNode> b = new ArrayList<TreeNode>();
		b.add(E);
		b.add(F);
		b.add(G);
		List<TreeNode> c = new ArrayList<TreeNode>();
		c.add(H);
		c.add(I);
		List<TreeNode> d = new ArrayList<TreeNode>();
		d.add(J);
		d.add(K);
		TreeNode B = new TreeNode("B", b);
		TreeNode C = new TreeNode("C", c);
		TreeNode D = new TreeNode("D", d);
		List<TreeNode> a = new ArrayList<TreeNode>();
		a.add(B);
		a.add(C);
		a.add(D);
		TreeNode A = new TreeNode("A", a);

		return A;

	}

	public void xianIterator(TreeNode node) {
		this.printNode(node);
		if (node.getChildRen() != null) {
			for (TreeNode child : node.getChildRen()) {
				this.xianIterator(child);
			}
		}

	}

	public void zhongIterator(TreeNode node) {

		if (node.getChildRen() != null) {
			TreeNode child = node.getChildRen().get(0);

			this.zhongIterator(child);

		}
		this.printNode(node);
		if (node.getChildRen() != null) {
			for (int i = 1; i < node.getChildRen().size(); i++) {
				TreeNode child = node.getChildRen().get(i);
				this.zhongIterator(child);
			}
		}

	}

	public void houIterator(TreeNode node) {

		if (node.getChildRen() != null) {
			for (TreeNode child : node.getChildRen()) {
				this.houIterator(child);
			}
		}
		this.printNode(node);

	}
}