hi,

use the fileoutputstream to save the tree back to file.i will give u a sample code and try it.
.
..
....

else if(e.getActionCommand().equals("Save"))
	   {try {
 fs = new FileOutputStream(fname,false);
      callrec();
       fs.close();
       refreshUI(fname); // build the tree
		
...
..
.
declare the fileo/pstream in the class
where u make declarations. 

callrec() is a method which contains code as ..

public void callrec() {
	
Object st = m_tree.getModel().getRoot();
System.out.println("
");
System.out.println("Root is ::"+st);
	DefaultMutableTreeNode mtn = (DefaultMutableTreeNode)st;
	TreeNode tn = mtn.getFirstChild();
	System.out.println("first child::"+tn);

	try
	{
	String s = tn.toString()+"
"; 
	byte b[];
	b=s.getBytes();
	fs.write(b);
	}
	catch(Exception eq)
	{
		System.out.println(eq);
	}	
	MutableTreeNode mt = (MutableTreeNode)tn;
	
	recursive(mt); // another method

if (mt.getChildCount() > 0)
{
  byte bb[];
  String s = mt.toString();
  s = "";
  bb = s.getBytes();
  try { 
 fs.write(bb);
 }
 catch(Exception e){}
System.out.println(s);
	}

.
..
...
public void recursive(MutableTreeNode tm)
{   try
   {
  for(int i=0;i   {
MutableTreeNode dts = (MutableTreeNode)tm.getChildAt(i);
String s = dts.toString();
System.out.println(s);
	byte b[];
	b = s.getBytes();
	fs.write(b); 
		 			if (dts.getChildCount() > 0 )
        {
		recursive(dts);
		}
if (dts.getChildCount() > 0)
{
			    		byte bb[];
s = "";
	bb = s.getBytes();
	fs.write(bb);
	System.out.println(s);
	}

				
		   }
		    
	      }//try
	    	    catch(Exception ew)
	    		{
		    		ew.printStackTrace();
	    		}    
}
	   	

if u r not clear mail me.