What are the cons of using in-place collection initializers in Java -

consider piece of code:

set<string> myset = new hashset<string>(){{add("foo");add("boo");}};

or hashmap:

map<string,string> mymap = new hashmap<string,string>(){{put("foo","bar");put("boo","jar");}};

pros find: less lines of code, conciseness. cons?

upd: question not sets, types of collections, added map illustrate this.

when that, creating anonymous subclass of hashset, means unnecessarily polluting code base of operations classes don't new.

how instead?

set<string> set = new hashset<string>(arrays.aslist("foo", "bar"));

or alternatively, utilize guava's sets class. has mill methods initialize different kinds of sets:

set<string> set = sets.newhashset("foo", "bar");

with maps it's trickier, can utilize immutablemap:

map<string,string> mymap = immutablemap.of("foo","bar","boo","jar");

or (mutable version)

map<string,string> mymutablemap = maps.newhashmap(immutablemap.of("foo","bar","boo","jar"));

without external libraries, can still initialize map single entry:

map<string,string> mymap = new hashmap<string, string>( collections.singletonmap("foo","bar") );

but 1 ugly beast, if inquire me.

upd: question not sets, types of collections, added map illustrate this.

guava has several mill classes this:

sets, maps, lists, multimaps, multisets, ranges

java collections map initialization set

JC