Use enum to create thead-safe factory instances

user_2746110 0
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I write the code for creating multiple instances for the thread-safe factory creation:

public class XWebserviceObjectFactoryCreator {
    
}

However, the code looks repeating to me and not happy about it. Is it possible to use enum (or something else) to make it more readable?

java
2 Answers

Since the example shows all the classes have no-argument constructors, you can use the Class.newInstance method, so something like :

private static Map<Class<?>, Object> instances = new HashMap<>();

public static <T extends Object> T getObjectFactoryInstance(Class<T> clazz)  {
    
    Object result;

    if ((result = instances.get(clazz)) == null) {                
            synchronized (instances) {

            if ((result = instances.get(clazz)) == null) { 
                 try {
                       result = clazz.newInstance();
                       instances.put(clazz, result)
                   } catch (InstantiationException |  IllegalAccessException e) {
                         // do something
                    }
              }
         }
    }

    return (T)result;
  }

Apologies if layout or syntax is off, but I’m away from my computer and doing this on the phone - but hope you get the idea !

If any classes do require arguments in their constructors, then you’ll have to use reflection to invoke the constructor.

Finally, note that I’ve modified the declaration of clazz from Class<?> to Class< T>, to let the generics validate the caller by tying the output to the given Class.

user_6814440

you can use the Abstract Factory design Pattern along with Enum where Sales2ObjectFactory, OrderingObjectFactory, Settings2ObjectFactory, and SettingsObjectFactory can be a factory in itself with a common interface.

Then you can use Enum to get the instance of one of those factories.

public static class FactoryMaker {

  public enum FactoryType {
    SALES2OBJECT, ORDERING,SETTING2OBJECT,SETTINGS
  }

  public static CommonFactory makeFactory(FactoryType type) {
    switch (type) {
      case SALES2OBJECT:
        return new Sales2ObjectFactory();
      case ORDERING:
        return new OrderingObjectFactory();
      case SETTING2OBJECT:
         return new Settings2ObjectFactory();
      case SETTINGS:
          return new new SettingsObjectFactory();
      default:
        throw new IllegalArgumentException("FactoryType not supported.");
    }
  }
}

Please check :: https://java-design-patterns.com/patterns/abstract-factory/

user_68051900
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