You can copy your xml file from assets folder by given code :
File toPath = Environment.getExternalStoragePublicDirectory(mAppDirectory);
if (!toPath.exists()) {
toPath.mkdir();
}
try {
InputStream inStream = getAssets().open("file.xml");
BufferedReader br = new BufferedReader(new InputStreamReader(inStream));
File toFile = new File(toPath, "file.xml");
copyAssetFile(br, toFile);
} catch (IOException e) {
}
private void copyAssetFile(BufferedReader br, File toFile) throws IOException {
BufferedWriter bw = null;
try {
bw = new BufferedWriter(new FileWriter(toFile));
int in;
while ((in = br.read()) != -1) {
bw.write(in);
}
} finally {
if (bw != null) {
bw.close();
}
br.close();
}
}
Reference : LINK