如何从数据库表中填充多级jtree [英] How to populate multilevel jtree from database table

问题描述

我有一个如下的数据库表。我想从表中制作动态jtree。



id姓名父母

1颜色null

2红色1

3白色1

4绿色1

5暗4

6光4



我尝试了什么：



要从数据库中检索表格，我已编写代码以下。

i have a database table like the following. I want to make dynamic jtree from the table.

id Name parent
1 color null
2 red 1
3 white 1
4 green 1
5 dark 4
6 light 4

What I have tried:

To retrieve the table from database i already written the code following.

while( rs.next() ) {  

 String parentId = rs.getString("node_Id");  
 String parentName = rs.getString("node_Name");
 String paren = rs.getString("node_Parent");
 int treeLvl = rs.getInt("node_Level");
// the above code is working perfectly fine, the problem start from here

 Map<String, DefaultMutableTreeNode> parentsMap
 = new HashMap<>();
    DefaultTreeModel tbl = (DefaultTreeModel) TreePro.getModel();
DefaultMutableTreeNode root = (DefaultMutableTreeNode)tbl.getRoot();

     DefaultMutableTreeNode Root = parentsMap.get(paren);

   Root = new DefaultMutableTreeNode( paren );

   parentsMap.put(parentId, Root );
   root.add(Root); 

 DefaultMutableTreeNode parent = parentsMap.get(parentName);

   parent = new DefaultMutableTreeNode( parentName );
   parentsMap.put(parentId, parent );
   Root.add(parent);

        }

现在它创建了这样的jtree



Root

Null

-color

颜色

-red

颜色

-white

颜色

-green

green

-dark

绿色

-light

显然它错了，我怎样才能从数据库表中正确地生成jtree。现在我希望我以正确的方式建立我的问题

Now it's creates jtree like this

Root
Null
-color
color
-red
color
-white
color
-green
green
-dark
green
-light
Obviously its wrong, how can i make jtree correctly from database table. Now i do hope i established my question in correct way

推荐答案

每次在循环中重新创建根节点。您应该在开头创建一次根节点。然后使用循环将所有子条目添加到根节点。

You are recreating the root node each time in the loop. You should create the root node once at the beginning. Then use the loop to add all the child entries to the root node.

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