Question

I’ve been using StringEscapeUtils.escapeHTML to escape URLs. Is there something similar to find out if the string is already escaped?

Answer 1

Not that I know of, but it is pretty easy to do one yourself:

public boolean isEscaped(String url) {
    return !url.equals(StringEscapeUtils.unEscapeHTML(url));
}

Note that deciding if a random string is escaped or not is impossible as @themel notes, you can get a lot of false positives if you try this with random strings. However I’m assuming that you at least have some control over what your strings look like here.