大家帮忙看看这个程序.改不出来哪错啊

[jailnever]

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.tree.*;
import javax.swing.event.*;
import java.util.*;
class Win extends JFrame implements TreeSelectionListener
{
Win (String s)
{
super (s);
Container con= getContentPane ();
DefaultMutableTreeNode root = new DefaultMutableTreeNode ("d:\\");
DefaultMutableTreeNode t1 = new DefaultMutableTreeNode ("dos");
DefaultMutableTreeNode t2 = new DefaultMutableTreeNode ("java");
DefaultMutableTreeNode t1_1 = new DefaultMutableTreeNode ("applet");
DefaultMutableTreeNode t1_2 = new DefaultMutableTreeNode ("jre");
root.add (t1);
root.add (t2);
t1.add (t1_1);
t1.add (t1_2);
JTree tree = new JTree (root);
JTextArea text = new JTextArea (12,12);
text.setEditable (false);
JScrollPane scrollpane1 = new JScrollPane (tree);
JScrollPane scrollpane2 = new JScrollPane (text);
con.add(scrollpane1,BorderLayout.WEST);
con.add(scrollpane2,BorderLayout.CENTER);
tree.addTreeSelectionListener (this);
addWindowListener (new WindowAdapter ()
{
public void windowClosing (WindowEvent e)
{
System.exit (0);
}
});
setVisible (true);
setBounds (80,80,300,300);
con.validate ();
validate ();
}
public void valueChanged (TreeSelectionEvent e)
{
DefaultMutableTreeNode node =
(DefaultMutableTreeNode) tree.getLastSelectedPathComponent ();
text.setText (null);
if (node.isLeaf())
{
if (node.toString ()=="jre")
{
text.append ("hello jre");
}
else if (node.toString ()=="applet")
{
text.append ("hello applet");
}
else if (node.toString ()=="java")
{
text.append ("hello java");
}
}
}
};
public class Tree
{
public static void main(String[] args)
{
Win win= new Win ("tree");
}
}

[yuzl32]

if (node.toString().equals ("jre"))
{
text.append ("hello jre");
}
else if (node.toString().equals("applet"))
{
text.append ("hello applet");
}
else if (node.toString().equals("java"))
{
text.append ("hello java");
}

[jailnever]

不是这个问题....

[cky417]

贴出错误提示

[hzhou]

1. 创建一个Tree.java
2. 将下面代码复制到Tree.java 中


import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.tree.*;
import javax.swing.event.*;
import java.util.*;
class Win extends JFrame implements TreeSelectionListener
{
private JTree tree=null;
private JTextArea text=null;
Win (String s)
{
super (s);
Container con= getContentPane ();
DefaultMutableTreeNode root = new DefaultMutableTreeNode ("d:\\");
DefaultMutableTreeNode t1 = new DefaultMutableTreeNode ("dos");
DefaultMutableTreeNode t2 = new DefaultMutableTreeNode ("java");
DefaultMutableTreeNode t1_1 = new DefaultMutableTreeNode ("applet");
DefaultMutableTreeNode t1_2 = new DefaultMutableTreeNode ("jre");
root.add (t1);
root.add (t2);
t1.add (t1_1);
t1.add (t1_2);
tree = new JTree (root);
text = new JTextArea (12,12);
text.setEditable (false);
JScrollPane scrollpane1 = new JScrollPane (tree);
JScrollPane scrollpane2 = new JScrollPane (text);
con.add(scrollpane1,BorderLayout.WEST);
con.add(scrollpane2,BorderLayout.CENTER);
tree.addTreeSelectionListener (this);
addWindowListener (new WindowAdapter ()
{
public void windowClosing (WindowEvent e)
{
System.exit (0);
}
});
setVisible (true);
setBounds (80,80,300,300);
con.validate ();
validate ();
}
public void valueChanged (TreeSelectionEvent e)
{
DefaultMutableTreeNode node =
(DefaultMutableTreeNode) tree.getLastSelectedPathComponent ();
text.setText (null);
if (node.isLeaf())
{
if (node.toString ()=="jre")
{
text.append ("hello jre");
}
else if (node.toString ()=="applet")
{
text.append ("hello applet");
}
else if (node.toString ()=="java")
{
text.append ("hello java");
}
}
}
};
public class Tree
{
public static void main(String[] args)
{
Win win= new Win ("tree");
}
}

[jailnever]

问题解决谢谢楼上各位

[yuzl32]

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.tree.*;
import javax.swing.event.*;
import java.util.*;
class Win extends JFrame implements TreeSelectionListener
{
private JTextArea text;
private JTree tree ;
Win (String s)
{
super (s);
Container con= getContentPane ();
DefaultMutableTreeNode root = new DefaultMutableTreeNode ("d:\\");
DefaultMutableTreeNode t1 = new DefaultMutableTreeNode ("dos");
DefaultMutableTreeNode t2 = new DefaultMutableTreeNode ("java");
DefaultMutableTreeNode t1_1 = new DefaultMutableTreeNode ("applet");
DefaultMutableTreeNode t1_2 = new DefaultMutableTreeNode ("jre");
root.add (t1);
root.add (t2);
t1.add (t1_1);
t1.add (t1_2);
tree = new JTree (root);
text = new JTextArea (12,12);
text.setEditable (false);
JScrollPane scrollpane1 = new JScrollPane (tree);
JScrollPane scrollpane2 = new JScrollPane (text);
con.add(scrollpane1,BorderLayout.WEST);
con.add(scrollpane2,BorderLayout.CENTER);
tree.addTreeSelectionListener (this);
addWindowListener (new WindowAdapter ()
{
public void windowClosing (WindowEvent e)
{
System.exit (0);
}
});
setVisible (true);
setBounds (80,80,300,300);
con.validate ();
validate ();
}
public void valueChanged (TreeSelectionEvent e)
{
DefaultMutableTreeNode node =
(DefaultMutableTreeNode) tree.getLastSelectedPathComponent ();
text.setText (null);
if (node.isLeaf())
{
if (node.toString ()=="jre")
{
text.append ("hello jre");
}
else if (node.toString ()=="applet")
{
text.append ("hello applet");
}
else if (node.toString ()=="java")
{
text.append ("hello java");
}
}
}
};
public class Tree
{
public static void main(String[] args)
{
Win win= new Win ("tree");
}
}