Use of JAVA JTree __java

Import java.awt.event.ActionEvent;
Import Java.awt.event.ActionListener;
Import Javax.swing.JFrame;
Import Javax.swing.JMenuItem;
Import Javax.swing.JOptionPane;
Import Javax.swing.JPopupMenu;
Import Javax.swing.JTree;
Import Javax.swing.tree.DefaultMutableTreeNode;
Import Javax.swing.tree.DefaultTreeModel;




/**
* A JTree maintenance code. Focus on
* 1) Get the way to select a node
* 2 the way to increase jpopmenu in JTree
* 3) Delete node
* 4) Modify the node
* @author Miao
*
*/
public class Showtree extends JTree {
Public Showtree (String rootname)
{
Super ();
Seteditable (TRUE);
Defaultmutabletreenode node = new Defaultmutabletreenode (rootname);
Defaulttreemodel TreeModel = new Defaulttreemodel (node);
Setmodel (TreeModel);

Addpopmenu ();

}

/**
* Add nodes to the data tree
* @param strsubnode
*/
public void Addtree (String strsubnode)
{
String inputstr = Joptionpane.showinputdialog ("Please enter a node name");
if (Inputstr.length () >0)
{
Strsubnode = Inputstr;
}

Defaultmutabletreenode node = (defaultmutabletreenode) getlastselectedpathcomponent ();

Defaultmutabletreenode subnode = new Defaultmutabletreenode (Strsubnode);
Node.add (subnode);
UpdateUI ();
}

public void Addpopmenu ()
{
JPopupMenu PopupMenu = new JPopupMenu ();
JMenuItem item = new JMenuItem ("Add");

Item.addactionlistener (new ActionListener () {
@Override
public void actionperformed (ActionEvent e) {
TODO auto-generated Method Stub
Addtree ("Newsubnode");
}
});
Popupmenu.add (item);

item = new JMenuItem ("delete");
Item.addactionlistener (new ActionListener () {

@Override
public void actionperformed (ActionEvent arg0) {
TODO auto-generated Method Stub
deltree ();
}
});
Popupmenu.add (item);

item = new JMenuItem ("Modify");
Item.addactionlistener (new ActionListener () {

@Override
public void actionperformed (ActionEvent e) {
TODO auto-generated Method Stub
Edittree ();
}
});
Popupmenu.add (item);

Setcomponentpopupmenu (PopupMenu);
}

/**
* Only input carriage return to modify the node value of the tree structure
*/
private void Edittree ()
{
Starteditingatpath (Getselectionpath ());
}

public void deltree ()
{
int option = Joptionpane.showconfirmdialog (null, OK) Are you sure you want to delete this node? ");
if (option==0)
{
SYSTEM.OUT.PRINTLN (option);
Defaultmutabletreenode node = (defaultmutabletreenode) getlastselectedpathcomponent ();
Node.removefromparent ();
UpdateUI ();
}
}

public static void Main (string[] args)
{
Showtree showtree = new Showtree ("This is Root");
JFrame JFrame = new JFrame ();
Jframe.getcontentpane (). Add (Showtree);
Swingconsole.run (jframe,0, 0);
}

}