def get_dex_names(self):
        """
        Return the names of all DEX files found in the APK.
        This method only accounts for "offical" dex files, i.e. all files
        in the root directory of the APK named classes.dex or classes[0-9]+.dex

        :rtype: a list of str
        """
        dexre = re.compile(r"classes(\d*).dex")
        return filter(lambda x: dexre.match(x), self.get_files())