Answer by Chase Seibert for How are anonymous inner classes used in Java?

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.