java递归构建菜单树

package testSimple;

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

public class BuildTree {
    public static void main(String[] args) {
        List<Tree> list = new ArrayList<Tree>();
        list.add(new Tree(1, "一级菜单", 0));
        list.add(new Tree(2, "二级菜单1", 1));
        list.add(new Tree(3, "二级菜单2", 1));
        list.add(new Tree(4, "二级菜单3", 1));
        list.add(new Tree(5, "三级菜单11", 2));
        list.add(new Tree(6, "三级菜单12", 2));
        list.add(new Tree(7, "三级菜单21", 3));
        list.add(new Tree(8, "三级菜单22", 3));
        list.add(new Tree(9, "三级菜单31", 4));
        list.add(new Tree(10, "三级菜单32", 4));

        List<Tree> result = buildTree(list, 0);
        System.out.println(result);
    }

    public static List<Tree> buildTree(List<Tree> list, int fid) {
        List<Tree> resultList = new ArrayList<Tree>();
        if (list == null || list.size() == 0 || fid < 0) {
            return null;
        }
        for (Tree tree : list) {
            if (tree.getFid() == fid) {
                resultList.add(tree);
                tree.setChildren(buildTree(list, tree.getId()));
            }
        }
        return resultList;
    }

}

class Tree {
    private int id;
    private String name;
    private int fid;
    private List<Tree> children;

    public Tree(int id, String name, int fid) {
        super();
        this.id = id;
        this.name = name;
        this.fid = fid;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getFid() {
        return fid;
    }

    public void setFid(int fid) {
        this.fid = fid;
    }

    public List<Tree> getChildren() {
        return children;
    }

    public void setChildren(List<Tree> children) {
        this.children = children;
    }

}