editing svg in batik problem

[milof83]

hi,

I'm a beginner with batik library and I need to create a program that
would allow me to edit existing svg files and the save them.

The code that I have written so far doesn't seem to be working. My
program doesn't want to access my svg file, however there are no erros
when i execute it.

public void editSVG (String inputFilename) throws Exception {

DOMImplementation impl = SVGDOMImplementation.getDOMImplementation();
String svgNS = SVGDOMImplementation.SVG_NAMESPACE_URI;
String svgURI = new File(inputFilename).toURL().toString();

SVGDocument doc;
try {
doc = (SVGDocument)impl.createDocument(svgURI, "svg", null);

// get the root element (the svg element)
Element svgRoot = doc.getDocumentElement();

// set the width and height attribute on the root svg element
svgRoot.setAttributeNS(null, "width", "400");
svgRoot.setAttributeNS(null, "height", "450");

// create the rectangle
Element rectangle = doc.createElementNS(svgNS, "rect");
rectangle.setAttributeNS(null, "x", "200");
rectangle.setAttributeNS(null, "y", "200");
rectangle.setAttributeNS(null, "width", "100");
rectangle.setAttributeNS(null, "height", "100");
rectangle.setAttributeNS(null, "fill", "red");

// attach the rectangle to the svg root element
svgRoot.appendChild(rectangle);

} catch (Exception e){
System.out.println("Error: " + e);
}
}

inputFilename is a string with my svg filename (test.svg)

I would be really grateful if somebody could help.