Abstract Class – An intentionally incomplete class definition. It may have some member variables and methods defined, but others are left as abstract using the abstract keyword. Non-abstract child classes must supply an implementation for these methods
Encapsulation – Encapsulation refers to the bundling of data with the methods that operate on that data.
from - http://www.developer.com/java/article.php/935351 An interesting description of encapsulation was recently given in another internet.com article By Rocky Lhotka regarding VB.NET. That description reads as follows: "Encapsulation is the concept that an object should totally separate its interface from its implementation. All the data and implementation code for an object should be entirely hidden behind its interface. The idea is that we can create an interface (Public methods in a class) and, as long as that interface remains consistent, the application can interact with our objects. This remains true even if we entirely rewrite the code within a given method thus the interface is independent of the implementation."
Child Class – A class that extends another class. The other class is referred to as a parent class. A child class may be used in any place that requires a parent class
Polymorphism –Polymorphism manifests itself in Java in the form of multiple methods having the same name. From a practical programming viewpoint, polymorphism manifests itself in three distinct forms in Java: * Method overloading * Method overriding through inheritance * Method overriding through the Java interface
Class – A type of data that defines both variables and methods.
Extend – The act of creating a child class from a parent class using the extends keyword. The child class inherits all of the parent’s member variables and methods, though it may not access any of the parent’s private variables and methods
GUI – Graphical User Interface. This describes the visual appearance of a program that allows a user to interact with non-text elements on the screen with a mouse. This is most commonly associated with windowed applications
Has-A – The relationship between an object and another object that has referenced it
Identity – The property of an object that causes it to be unique, even if other objects have been created from the same class
Inheritance – The ability of a class to possess any of its parent’s member variables and use its protected, package protected, or public methods
Instance – An object that has been created from a class at program run-time.
Interface – A Java construct that supplies a definition for methods. Any class that implements an interface is guaranteed to have the methods described in the interface. A class may implement any number of interfaces
Is-A – The relationship between a child class and its parent class. When a class extends another class using the extends keyword it exhibits this relationship
JAR File – A compressed file containing class files. These files may be used in other Java programs
Lifetime – The property of an object that describes whether it is in existence or not. Objects’ lifetimes end when they are no longer referenced. This occurs most often when a reference to an object goes out of scope and the object is garbage collected. Objects possess their own lifetime, independent of each other even if they are created from the same class
Method – A set of instructions in a class. Also known as a Function or Procedure
Object – A space in memory with variables and methods, which has been created at runtime from a class. An object is said to have its own identity, state, and lifetime
Package – A grouping of classes that may interact and support each other and are used to perform similar tasks. Classes that are in the same package are defined using the package keyword
Package Protected – Access restriction that only allows classes in the same package to read and write its member variables and use its methods
Parent Class – A class that has been extended by another class. The other class is referred to as a child class. A parent class may not be used in any place that specifically requires a child class
Polymorphism – The mechanism that allows an object to be an instance of itself and any of its parent classes or implemented interfaces. This property allows an instance of a child class to be used in any place a method requires one of its parent classes or interfaces
Private – Access restriction that allows no other class or instance of a class to read and write its member variables and use its methods
Protected – Access restriction that only allows children of a parent class and no other class to read and write its member variables and use its methods
Public – Access restriction that allows any class to read and write its member variables and use its methods
State – The property of an object that describes it condition, based upon the contents of its member variables. Objects may possess their own state, independent of each other even if they are created from the same class
Swing – The Sun Microsystems provided Java package that allows user to create windowed applications
Type-Casting – An instruction that informs the Java Virtual Machine how to treat a specific reference or variable
Uses-A – The relationship between objects that call methods and use member variables of other objects