似乎問題,你永遠不添加bird
節點到您的JTree
,使用root.add(bird);
。
如果您的根節點已經包含鳥節點,您需要在root
中搜索並且不創建新節點。如果將新節點添加到可見樹中,也可以使用model.nodesWereInserted(NODE, new int[]NODE.getChildCount()-1});
。 NODE
- 添加新子項的節點。
實施例:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Enumeration;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
public class TestFrame extends JFrame {
private JTree t;
public TestFrame() {
init();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
setLocationRelativeTo(null);
setVisible(true);
}
private void init() {
DefaultMutableTreeNode root = new DefaultMutableTreeNode("root");
DefaultMutableTreeNode bird = new DefaultMutableTreeNode("Birds");
root.add(bird);
DefaultTreeModel model = new DefaultTreeModel(root);
add(t=new JTree(model));
JButton btn = new JButton("add");
btn.addActionListener(getAddListener());
add(btn,BorderLayout.SOUTH);
}
private ActionListener getAddListener() {
return new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
DefaultTreeModel model = (DefaultTreeModel)t.getModel();
DefaultMutableTreeNode root = (DefaultMutableTreeNode) model.getRoot();
Enumeration children = root.children();
while(children.hasMoreElements()){
DefaultMutableTreeNode node = (DefaultMutableTreeNode) children.nextElement();
if(node.toString().equals("Birds")){
DefaultMutableTreeNode sparrow = new DefaultMutableTreeNode("sparrow");
DefaultMutableTreeNode cuckoo = new DefaultMutableTreeNode("cuckoo");
node.add(sparrow);
node.add(cuckoo);
model.nodesWereInserted(node, new int[]{node.getChildCount()-1,node.getChildCount()-2});
break;
}
}
}
};
}
public static void main(String args[]) {
new TestFrame();
}
}
爲了更好地幫助越早,張貼[MCVE](http://stackoverflow.com/help/mcve)(最小完備可驗證實施例)。 – 2014-10-28 10:30:33
先生,如何發佈一個MCVE – ddk 2014-10-28 10:34:14
「但我不能添加麻雀,布穀鳥。」 - 什麼是錯誤? – RobAu 2014-10-28 10:34:31