谈到 JTree
时,我已经用头撞砖墙好几天了!
我想创建一个 JTree
,它在运行时从 mp3 标签动态获取其内容。到目前为止一切顺利,除了在填充 JTree 时我非常头疼。经过多次实验,我终于放弃并寻求帮助。我一直在使用下面创建的类来尝试将子节点添加到 JTree 中现有节点的方法。我遇到的问题是在 try block 内,类型不兼容。我收到的错误是:
error: incompatible types: `TreeNode` cannot be converted to `MutableTreeNode`
treeModel.insertNodeInto
需要 MutableTreeNode
作为其第二个参数。我用来获取第二个参数的父节点的方法 rootNode.getChildAt()
返回 TreeNode
。
还有这个吗???现在有人知道为什么 getChildAt()
返回一个 TreeNode
对象而不是 DefaulMutableTreeNode
吗?对象类型 rootNode
已初始化作为???
package jtreeex;
import java.util.Enumeration;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeSelectionModel;
/**
*
* @author david
*/
public class JTreeEx implements Runnable
{
public JTreeEx()
{
JFrame jfrm = new JFrame();
JPanel panel = new JPanel();
JTree tree;
DefaultMutableTreeNode rootNode;
rootNode = new DefaultMutableTreeNode("Audio");
DefaultTreeModel treeModel = new DefaultTreeModel(rootNode);
treeModel.addTreeModelListener(new MyTreeModelListener());
tree = new JTree(treeModel);
tree.setEditable(true);
tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
tree.setShowsRootHandles(true);
String [] anArray = {"Dogs", "Cats"};
// Inserts new root nodes from anArray
for(int i = 0; i < anArray.length; i++)
{
treeModel.insertNodeInto(new DefaultMutableTreeNode(anArray[i]),
rootNode, rootNode.getChildCount());
}
// Get enumeration of children of rootNode
Enumeration eNum = rootNode.children();
try
{
while(eNum.hasMoreElements() == true)
{
treeModel.insertNodeInto(new DefaultMutableTreeNode("Toby"),
rootNode.getChildAt(1), rootNode.getChildCount());
}
}
catch (Exception e)
{
System.out.println("no enums left");
}
panel.add(tree);
jfrm.add(panel);
jfrm.setSize(400,200);
jfrm.setVisible(true);
jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
(new Thread(new JTreeEx())).start();
}
public void run()
{
}
}
最佳答案
treeModel.insertNodeInto requires MutableTreeNode for its second argument. The method im using to get the parent node for the second argument, rootNode.getChildAt() returns TreeNode.
您正在构建树,并且知道正在将 DefaultMutableTreeNode 插入到树中,因此只需将 TreeNode 转换为 DefaultMutableTreeNode:
treeModel.insertNodeInto(new DefaultMutableTreeNode("Toby"),
(DefaultMutableTreeNode)rootNode.getChildAt(1), rootNode.getChildCount());
关于java - JTree的动态初始化,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/24308479/