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;
     }

 }