Classes and objects in Java must be initialized before they are used. You’ve previously learned that class fields are initialized to default values when classes are loaded, and that objects are ...

All classes in Java can have a single base class that they extend. When you extend another class you inherit all of the public and protected methods and fields that the class provides. The default ...

Teacher extends Person, which extends Object. Note: Java's Object class is poorly named because an "object" is usually an instance of a class. But the class that all classes ultimately and implicitly ...

Classes, fields, methods, constructors, and objects are the building blocks of object-based Java applications. This Java tutorial teaches you how to declare classes, describe attributes via fields ...

Object-oriented systems are usually partitioned into layers of related responsibilities and only dependencies in one direction are allowed, from higher layers (more specific, less reusable) to lower ...