java--树封装

Multimap：允许key值相同，不会覆盖掉之前的数据。用于封装类似于Map<Object,List<Object>>这种有嵌套结构的数据。Maven坐标如下：

<dependency> <groupId>com.google.guava</groupId> <artifactId>guava</artifactId> <version>10.0.1</version> </dependency>

1.定义树结构

public class MyTree { private String id; private String parentId; private String name; private List<MyTree> child = Lists.newArrayList(); //getter()、setter()方法。。。　　 public void addChild(MyTree tree){ child.add(tree); }

2.支持多层次的树封装：　　

//2万条数据封装耗时15ms public Collection<MyTree> getCompleteTrees() { //获取数据 List<MyTree> treeList = initList(); //树节点封装 Multimap<String, MyTree> multimap = treeNodePackageByParentId(treeList); //获取根节点 Collection<MyTree> rootNodeList = multimap.get("0"); //添加子节点 addTreeNodeDependency(rootNodeList, multimap); return rootNodeList; }//按parentId聚合 private Multimap<String, MyTree> treeNodePackageByParentId(List<MyTree> treeList) { Multimap<String, MyTree> multimap = HashMultimap.create(); for (MyTree treeNode : treeList) { multimap.put(treeNode.getParentId(), treeNode); } return multimap; }//添加依赖关系 private void addTreeNodeDependency(Collection<MyTree> rootTreeList, Multimap<String, MyTree> multiMap) { for (MyTree parentTreeNode : rootTreeList) { addChildNode(parentTreeNode, multiMap); } } private void addChildNode(MyTree parentTreeNode, Multimap<String, MyTree> multiMap) { String id = parentTreeNode.getId(); for (MyTree chileTreeNode : multiMap.get(id)) { String childId = chileTreeNode.getId(); parentTreeNode.addChild(chileTreeNode); if (multiMap.containsKey(childId)) { addChildNode(chileTreeNode, multiMap); } } } //----------算法性能差，时间复杂度O(n*n),2万条数据封装耗时20s-------------//获取数据List<MyTree> treeList=initList(); MyTree resultTree=null;//添加父节点和子节点依赖关系　　　　　 for(MyTree outTree:treeList){ String id=outTree.getId();　　//找到根节点 if("0".equals(outTree.getParentId())){ resultTree=outTree; } for(MyTree innerTree:treeList){ String parentId=innerTree.getParentId(); if(id.equals(parentId)){ outTree.addChild(innerTree); } }}

3.数据结构如下：

idparentIdname10中国21江苏省32南京市42徐州市54新沂市61浙江省76杭州市

 

 

 

 

 

 

 

 

4.运行结果如下：

 

转载于:https://www.cnblogs.com/jvStarBlog/p/10957886.html

相关资源：JAVA上百实例源码以及开源项目