Learn the difference between classes and interfaces once and for all, then get started declaring, implementing, and extending interfaces in your Java programs ...

The terms JVM tuning and Java optimization are often used interchangeably, but there is an important difference between the two practices. In short, JVM tuning requires some tradeoff between metrics ...

For an introduction to Java interfaces, including the difference between classes and interfaces, see my Java 101 tutorial Working with interfaces in Java. Nesting interfaces in classes ...