Almost literals - Initializing Java collections

Dynamic languages like Python and Ruby provide built-in syntax to express common data structures as literals. However, Java provides literal syntax only for arrays.

Although not pretty, here is how you can quickly initialize Java collections:

import java.util.*;

public class Literals {
   private static class HashMapNow<K, V> extends HashMap<K, V> {
       public HashMapNow<K, V> with(K key, V value) {
           put(key, value);
           return this;
       }
   }
  
   public static void main(String[] args) {
       // initialize a list
       List<String> list = Arrays.asList("a", "b", "c", "c");
      
       // initialize a set
       Set<String> set = new HashSet<String>(Arrays.asList("a", "b", "c", "c"));
      
       // initialize a map
       Map<String, String> map = new HashMapNow<String, String>()
       .with("a", "1")
       .with("b", "2")
       .with("c", "3")
       .with("c", "4");
      
       // print them all
       System.out.println(list);
       System.out.println(set);
       System.out.println(map);
   }
}

2009 Aug 25 [Update]: As suggested by Eric (in comments below), the initialization can be done in the static block - though it is admittedly quirkier. Cleaner options are available in Google Collections and LambdaJ.