Enter Java nested classes. The first time I laid eyes on these, I couldn’t imagine a single use for them that I wouldn’t prefer to implement some other way. Then I noticed something very ...

It’s a good idea to use an abstract class when you need to implement mutable state. As an example, the Java Collections Framework includes the AbstractList class, which uses the state of variables.

Library authors would prefer to use interfaces to expose opaque abstractions; abstract classes were meant to be an implementation aid, not a modeling tool. (See Effective Java, "Prefer interfaces ...

The modifier non-sealed is the first hyphenated keyword proposed for Java. The non-sealed keyword brings flexibility into the rigid world of sealed classes, to allow a particular implementation to ...

To implement the objects ... each object to define only the features that are different from the Animal class. Java uses the keyword extends to indicate that one class inherits from another.

The result clearly demonstrates behaviors that would not commonly be observed with the default implementation. import java.util.HashMap; import java.util.HashSet; public class HashAndProperty { int ...

Without access to the test suite, the Harmony developers were not able to certify their implementation's conformance with the Java standard, thus creating the risk of fragmentation. Commercial ...