由 SQL 查询填充的 Java Jtree

Question

我想从一个二维对象数组创建一个 JTree，我将从 SQL 查询中导入该数组。这是 SQL 表的样子：

这是对象的示例：

    Object[][] table = {
        {1, 0, "Root"}, //i=0
        {2, 1, "Node2"}, //i=1
        {3, 1, "Node3"}, //i=2
        {4, 1, "Node4"}, //i=3
        {5, 4, "Node5"}, //i=4
        {6, 4, "Node6"}, //i=5
        {7, 4, "Node7"}, //i=6
        {8, 1, "Node8"}, //i=7
        {9, 1, "Node9"}, //i=8
        {10, 9, "Node10"},}; //i=9

这是我用来对数组进行排序的逻辑：

    for (int i = 0; i < table.length; i++) {
        for (int j = i; j < table.length; j++) {
            if (table[i][0] == table[j][1]) {
                System.out.println(table[i][2].toString() + " is parent of " + table[j][2].toString());
            }
        }
    } 

这是上面在控制台中显示的内容：

 Root is parent of Node2
 Root is parent of Node3
 Root is parent of Node4
 Root is parent of Node8
 Root is parent of Node9
 Node4 is parent of Node5
 Node4 is parent of Node6
 Node4 is parent of Node7
 Node9 is parent of Node10

我正在努力创建可用于创建 JTree 的 TreeModel、HashTable、Object 等。

我已经被这个问题困扰了一个多星期，现在我真的可以借鉴其他人的经验。

Answer 1

将您的数据组织到这些列中：

CREATE TABLE tree_node
(NodeID int,
ParentID int,
Value varchar(250)
...) //as many values per node as you want

这将允许您遍历记录集并填充您的 JTree。

看看depth first 和breadth first 树遍历。

Answer 2

我是 Java 新手，所以我不得不对这个问题进行一些研究。研究真的很费时间。我发现以下链接具有从 SQL 数据创建 JTree 的最佳解决方案。

https://forums.oracle.com/forums/thread.jspa?threadID=2225475

这是我用来解决问题的代码

class myTree extends JPanel {

private DefaultMutableTreeNode rootNode;
private DefaultTreeModel treeModel;

public myTree() {

    super(new GridLayout(1, 1)); //Set the layout for the panel that the jtree.

    //The following object is a sample from a database and was used to validate 
    //the solution below. Make sure the table is properly sorted before you create the 
    //the object from the query.
    Object[][] table = {
        {1, null, "Root"}, //i=0
        {2, 1, "Node2"}, //i=1
        {3, 2, "Node3"}, //i=2
        {4, 3, "Node4"}, //i=3
        {5, 4, "Node5"}, //i=4
        {6, 5, "Node6"}, //i=5
        {7, 6, "Node7"}, //i=6
        {8, 1, "Node8"}, //i=7
        {9, 1, "Node9"}, //i=8
        {10, 9, "Node10"},};    //i=9

    //Create as many nodes as there are rows of data.
    DefaultMutableTreeNode[] node = new DefaultMutableTreeNode[table.length];
    for (int i = 0; i < table.length; i++) {
        node[i] = new DefaultMutableTreeNode(table[i][2].toString());
    }

    rootNode = node[0];   //Set the root node

    //Cycle through the table above and assign nodes to nodes
    for (int i = 0; i < table.length; i++) {
        for (int j = 1; j < table.length; j++) {
            if (table[i][0] == table[j][1]) {
                System.out.println(table[i][2].toString() + " is parent of " + table[j][2].toString());
                node[i].add(node[j]);
            }
        }
    }
    //Creating the tree model. setting the root node.
    treeModel = new DefaultTreeModel(rootNode);
    //Setting the tree model to the JTree
    JTree tree = new JTree(treeModel);
    //adding the tree to the JPanel
    add(tree);
}