### Relevant Articles:
- [A Guide to the Front Controller Pattern in Java](http://www.baeldung.com/java-front-controller-pattern)
- [Introduction to Intercepting Filter Pattern in Java](http://www.baeldung.com/intercepting-filter-pattern-in-java)
- [Introduction to the Null Object Pattern](https://www.baeldung.com/java-null-object-pattern)
- [The Dependency Inversion Principle in Java](https://www.baeldung.com/java-dependency-inversion-principle)
- [Avoid Check for Null Statement in Java](https://www.baeldung.com/java-avoid-null-check)