// This java app will make 

// The input XML (serve as a template) looks like this:
 /*
    <root>
      <a> some content </a>
      <b>              </b>
      <c>              </c>
    </root>  
  */  

// The output XML looks like this:

/*
 	<root>
 	   <a>  123		   </a>
 	   <b>  234        </b>
 	   <c>new content  </c>
    </root>  
 */
import com.ximpleware.*;
import java.io.*;

public class overWrite {
    public static void main(String[] args) throws Exception {
        VTDGen vg = new VTDGen();
        if (vg.parseFile("old.xml",false)){
            VTDNav vn = vg.getNav();
            if (vn.toElement(VTDNav.FIRST_CHILD)){
                // cursor at <a>
                int i = vn.getText();
                if (vn.overWrite(i,"  123".getBytes())==false){
                    System.out.println("overWrite at "+i+" failed");
                }
                // cursor at <b>
                vn.toElement(VTDNav.NEXT_SIBLING);
                i = vn.getText();
                if (vn.overWrite(i,"  234".getBytes())==false){
                    System.out.println("overWrite at "+i+" failed");
                }
                // cursor at <c>
                vn.toElement(VTDNav.NEXT_SIBLING);
                i = vn.getText();
                if (vn.overWrite(i,"new content".getBytes())==false){
                    System.out.println("overWrite at "+i+" failed");
                }
                
                byte[] ba = vn.getXML().getBytes();
                FileOutputStream fos = new FileOutputStream("new.xml");
                fos.write(ba);
            }
        }
    }
}