How are Anonymous inner classes used in Java?

Question

What is the use of anonymous classes in Java? Can we say that usage of anonymous class is one of the advantages of Java?

Answer 1

I use them sometimes as a syntax hack for Map instantiation:

Map map = new HashMap() {{
   put("key", "value");
}};

vs

Map map = new HashMap();
map.put("key", "value");

It saves some redundancy when doing a lot of put statements. However, I have also run into problems doing this when the outer class needs to be serialized via remoting.