gistfile1.txt

    
public interface KeyValueFunction<KI, VI, KO, VO> {

    Map.Entry<KO, VO> f(KI k, VI v);
}
/**
     * Creates a new map by applying each element to the converter.
     *
     * @param <KI> key type of input map
     * @param <VI> value type of input map
     * @param <KO> key type of result map
     * @param <VO> value type of result map
     * @param in
     *            input map
     * @param converter converts a input key-value-pair into an output pair
     * @return map of the same size and order
     */
    public static <KI, VI, KO, VO> Map<KO,VO> applyToMap(final Map<KI,VI> in, final KeyValueFunction<KI, VI, KO, VO> converter) {
        final Map<KO, VO> result = new LinkedHashMap<KO, VO>(in.size());

        for (final Map.Entry<KI, VI> entry : in.entrySet()) {
            Entry<KO, VO> converted = converter.f(entry.getKey(), entry.getValue());
            result.put(converted.getKey(), converted.getValue());
        }
        return result;
    }

###################### IMPL ###################

    private static class Block3Group extends SimpleEntry<Block3GroupType, Collection<WorkstreamMessage>> implements Map.Entry<Block3GroupType, Collection<WorkstreamMessage>> {
        private static final long serialVersionUID = -8798387190864601959L;

        public Block3Group(Block3GroupType type,
                Collection<WorkstreamMessage> content) {
            super(type, content);
        }
    }


    private static final KeyValueFunction<
        Block3GroupType, Collection<WorkstreamMessage>, // input
        Block3GroupType, Collection<WorkstreamMessage>> // output
        CROP_GROUP_FUNCTION = 
            new KeyValueFunction<Block3GroupType, Collection<WorkstreamMessage>, 
                                Block3GroupType, Collection<WorkstreamMessage>>() {

        @Override
        public Block3Group f(Block3GroupType groupType, Collection<WorkstreamMessage> entries) {
          ...do stuff ..
        }
    }