Problem Three: Merchant's Guide to the Galaxy

public interface MerchantGuideProcessor {
    void setInputReader(InputReader inputReader);

    void setOutputWriter(OutputWriter outputWriter);

    void process() throws ProcessException;
}

public class MerchantGuideProcessorImpl implements MerchantGuideProcessor {

    private InputReader inputReader;
    private OutputWriter outputWriter;
    private IntergalacticUnitCalculator intergalacticUnitCalculator;
    private MerchandiseCalculator merchandiseCalculator;
    // ......
}