void setFileFilter() {
setFileFilter(SimpleFilter.extension(file));
}
void setFileFilter(String ext) {
if (ext == null) return;
SimpleFilter f = (SimpleFilter)filters.get(ext);
if (f != null) fileD.setFileFilter(f);
else {
f = new SimpleFilter(ext, "*."+ext);
filters.put(ext, f);
fileD.addChoosableFileFilter(f);
}
}