0If we want to reuse the java code that should be the best approach w.r.t re-usability, maintanence and saving time to concentrate on our own businbess logic/requirement. In the similar approach many patterns has been evolved which gives developer a opennes to decouple the functional logic and deploy as plug and play which is so famous as plugins in programming world.
The plugins gives developer feasibility to reuse and extend the existing/implemented features and get benefited with that. Using the Jars we can de-couple our object creation like factory pattern and create the object at runtime depends upon the implementing factory class available on classpath. Service locator also works in same way where service provider need to define a descriptor file with the full class name of its abstract class (or interface) which contains the information of URI and its corresponding full implenting class. This way the vendor can publish its factory and implementing class within jar and put on class path to automatically come into action.
Tomorrow, if requirement gets changed or we recommended to use any other factory then simply we can add the updated jar into appended classpath and if it will get loaded first then it will be in action. So it is so easy to directly plug & play with such user frindly pattern. Such patterns are mostly we can see with xml parsers.
