Abstract classes and interfaces are plentiful in Java code, and even in the Java Development Kit (JDK) itself. Each code element serves a fundamental purpose: Interfaces are a kind of code ...

Most introductory Java texts take an implementation-centric stab at how to use interfaces and abstract classes. However, few provide a clear design distinction for choosing between these two ...

For example, using the keyword implements will make a Java interface, while the keyword extends makes an abstract class. Abstraction vs. encapsulation Encapsulation in object-oriented programming is ...

Basically ComponentA depends on ComponentB. To enable unit-testing class ComponentAImpl, the implementation of interface ComponentB must be injected into ComponentAImpl. The Java code below shows the ...