builder for HashMap

Question

Guava provides us with great factory methods for Java types, such as Maps.newHashMap().

But are there also builders for java Maps?

HashM         


        

Answer 1

A simple map builder is trivial to write:

public class Maps {

    public static  MapWrapper map(Q q, W w) {
        return new MapWrapper(q, w);
    }

    public static final class MapWrapper {
        private final HashMap map;
        public MapWrapper(Q q, W w) {
            map = new HashMap();
            map.put(q, w);
        }
        public MapWrapper map(Q q, W w) {
            map.put(q, w);
            return this;
        }
        public Map getMap() {
            return map;
        }
    }

    public static void main(String[] args) {
        Map map = Maps.map("one", 1).map("two", 2).map("three", 3).getMap();
        for (Map.Entry entry : map.entrySet()) {
            System.out.println(entry.getKey() + " = " + entry.getValue());
        }
    }
}