A class is a template, or a blueprint, from which Java objects are created. All Java programs start with a class.
A method is a way to teach the computer a new command
A variable defined in a Class, for which each object of the class has its own copy.
A constructor is a special method of a Class that constructs a new object (a new instance) of the Class and sets the initial values for the instance variables.
A method that enables user to obtain information about an object’s instance and static variables.
A method that enables user to change the value of an object’s instance and static variables.
A keyword that indicates a reference object doesn’t point to any object data.
A type of interface that uses interactive graphical elements such as windows, buttons, and icons.
when programs are used and tested without the user necessarily understanding how each part of the program is working, but are able to understand what the final output or product will be.
When a subclass extends a superclass, the subclass inherits all of the static methods, static variables, and public instance methods of the superclass. This is called inheritance.
A child class that inherits attributes and behaviors from a superclass (parent).
If a class A extends the class B, then A is a subclass of B.
If a class A extends the class B, then B is the superclass of A.
An object can take on different forms depending on its implementation. Java can call the correct method even when an object is disguised as a more generic reference type
