Answer by Glenn for Take an xml feed from the internet and put it in my assets

Writing an xml file or any file in assets folder at runtime is impossible. Folders or resources in res folder are "read only" but, you can write an XML file on your application's internal data folder.

Just use the Context.openFileInput(String) and Context.openFileOutput(String, int). Here

Update 1:

This question might come on your mind.

"If I write an XML file on my app's data folder, how to parse it?"

You can use XMLPullParser class to parse an XML File. Here's an example

XMLPullParser parser = Xml.newPullParser();
parser.setInput(new InputStreamReader(openFileInput("my_XML_file.xml")));