private String replaceIllegalCharacters(String filename){
  for (  String illegalCharacter : mIllegalCharacters) {
    filename=filename.replace(illegalCharacter,"_");
  }
  return filename;
}

private String replaceIllegalCharacters ( String filename ) { for ( String illegalCharacter : mIllegalCharacters ) { filename = filename . replace ( illegalCharacter , "_" ) ; } return filename ; }
replaces any illegal filename characters in the proposed filename
