A type-safe map-like class

In the forceTen GeoCoding API there's a simple map-like class named FactSheet, that contains a few attributes about a geographic entity (such as the population count, or the official elevation of the place). It's the typical scenario where you'd use a Map or a map-like class, because data items can be there or not for some entities and/or for different service providers. This class is used with something like: FactSheet factSheet = ... if (factSheet.contains("population"))   {     long population = (long)factSheet.get("population");   } where a logical improvement is to define a String constant POPULATION to use as the key. The little annoyance is the required (long) cast, which also jeopardize the IDE auto-completion code (the “assign to variable” shortcut would generate an Object). It's easy to make an error here: is POPULATION an int or a long? ELEVATION will be a float or a double, or an int? This can be easily solved by replacing the String POPULATION with a simple generified Key: @Immutable public final static class Key implements Comparable   {     @Nonnull     private final String name;     protected Key (final @Nonnull String name)       {         this.name = name;       }     @Override     p...

Date: January, 11 2010
Url: http://www.java.net/blog/fabriziogiudici/archive/2010/01/11/type-safe-map-class

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