Java enum-based factory to calculate entry parameters

Question

I want to create a factory to return all Source instances that match given entry parameters- that is, I want to iterate through some Collection of objects and for each entry check boolean method. I thought about enum, as I'm guaranteed to iterate through them all. I came up with something like this:

simple interface

public interface Source {
 public boolean isPresent(SourceCalculationData data);
 public Source2 getType();
}

my take on enum factory:

public enum Source2 {
 IB("IB", SourceIb.class),
 CCWEW("BOT", SourceCcwew.class),
 OBD("CUF", SourceCuf.class),
 PB("PB", SourcePb.class),
 COK("COK", SourceCok.class),
 CCZEW("CCZ", SourceCczew.class),
 CRM("CRM", SourceCrm.class),
 APP("APP", SourceApp.class);
 private static final Logger SENSITIVE_LOGGER = SensitiveLoggerFactory.getSensitiveLogger(Source2.class);
 private String configChannel;
 private Class<? extends Source> clazz;
 private Source2(String configChannel, Class<? extends Source> clazz) {
 this.configChannel = configChannel;
 this.clazz = clazz;
 }
 public Class<? extends Source> getClazz() {
 return clazz;
 }
 public String getConfigChannel() {
 return configChannel;
 }
 public Source getSource() {
 return getAction(clazz);
 }
 private Source getAction(Class<? extends Source> source2Class) {
 try {
 return source2Class.newInstance();
 } catch (InstantiationException | IllegalAccessException e) {
 SENSITIVE_LOGGER.warn("<< Exception occured during init of {}, returning unkown source.", source2Class);
 return new SourceUnkown();
 }
 }

and use case:

 final SourceCalculationData data = new SourceCalculationData();
 final EnumSet<Source2> presentSources = EnumSet.noneOf(Source2.class);
 for (final Source2 source2ToCheck : Source2.values()) {
 if (source2ToCheck.getSource().isPresent(data)) presentSources.add(source2ToCheck);
 }

I'm pretty sure this is not the best code in the world. Any suggestions what will make it better?

• konijn: Greetings & Salutations, to prevent this from being closed; I would take out the implementation of SourceIb, since we don't review stubs. Ideally you would also figure out your logging and error handling before submitting the code.

Answer 1

Your implementation is good, but I would suggest following points to improve:

1. It is really hard to test/mock source2ToCheck.getSource().
2. Source2 contains a lot logic/functionality (it is source type and factory) it has to be simplified.
3. getSource() creates new course object it is confusing
4. getSource(...) calls getAction(...) that create a source object. It is wired.
5. Be aware source2Class.newInstance() is deprecated since java 9 source2Class.getDeclaredConstructor().newInstance()

Suggestions:

• I would propose to create dedicated interface/class for source factory
• Rename Source2 to SourceType.
• Throw custom exception CustomCantCreateSourceException instead of return new SourceUnkown(). Because it is real exceptional situation.
• Remove public methods modifier from Source interface
• Minor enhancements you can find in following code

Source Factory interface:

public interface SourceFactory {
 Source create(SourceType type);
}

Factory implementation:

public class SourceFactoryImpl implements SourceFactory {
 @Override
 public Source create(SourceType type) {
 try {
 return type.getClazz().getDeclaredConstructor().newInstance();
 } catch (InstantiationException | IllegalAccessException
 | NoSuchMethodException | InvocationTargetException e) {
 SENSITIVE_LOGGER.warn("<< Exception occured during init of {}, returning unkown source.", source2Class);
 throw new CustomCantCreateSourceException();
 }
 }
}

Renamed Source2:

public enum SourceType {
 IB("IB", SourceIb.class),
 CCWEW("BOT", SourceCcwew.class),
 OBD("CUF", SourceCuf.class),
 PB("PB", SourcePb.class),
 COK("COK", SourceCok.class),
 CCZEW("CCZ", SourceCczew.class),
 CRM("CRM", SourceCrm.class),
 APP("APP", SourceApp.class);
 private static final Logger SENSITIVE_LOGGER = SensitiveLoggerFactory.getSensitiveLogger(SourceType.class);
 private String configChannel;
 private Class<? extends Source> clazz;
 private SourceType(String configChannel, Class<? extends Source> clazz) {
 this.configChannel = configChannel;
 this.clazz = clazz;
 }
 public Class<? extends Source> getClazz() {
 return clazz;
 }
 public String getConfigChannel() {
 return configChannel;
 }
}

Usage:

public class SourceService {
 private final SourceFactory factory;
 public SourceService(SourceFactory factory) {
 this.factory = factory;
 }
 public EnumSet<SourceType> fillSources() {
 final SourceCalculationData data = new SourceCalculationData();
 final EnumSet<SourceType> presentSources = EnumSet.noneOf(SourceType.class);
 for (final SourceType source2ToCheck : SourceType.values()) {
 if (factory.create(source2ToCheck).isPresent(data)) {
 presentSources.add(source2ToCheck);
 }
 }
 return presentSources;
 }
}