Java (anonymous or not) inner classes: is it good to use them?

Question

In some of my projects and in some books was said to not use inner class (anonymous or not, static or not) - except in some restricted conditions, like

Answer 1

Certain frameworks, like Wicket, really require anonymous inner classes.

Saying never is silly. Never say never! An example of good use might be a situation where you have some legacy code that was written by someone where many classes operate directly on a Collection field, and for whatever reason, you cannot change those other classes, but need to conditionally mirror operations to another Collection. The easiest thing to do is to add this behavior via an anonymous inner class.

bagOfStuff = new HashSet(){
  @Override
  public boolean add(Object o) {
    boolean returnValue = super.add(o);
    if(returnValue && o instanceof Job)
    {
      Job job = ((Job)o);
      if(job.fooBar())
         otherBagOfStuff.add(job);
    }
    return returnValue;
  }
}

That said, they can definitely be used like a poor man's closures.