v
A bstraction: Showing the
essential and hiding the non-Essential is known as Abstraction.
v
E encapsulation: The Wrapping up of data and functions into a
single unit is known as Encapsulation.
Encapsulation is the
term given to the process of hiding the implementation details of the object.
Once an object is encapsulated, its implementation details are not immediately
accessible any more. Instead they are packaged and are only indirectly accessed
via the interface of the object.
v Inheritance: is the Process by which the Obj of one class acquires the
properties of Obj’s another Class.
A reference variable of a Super
Class can be assign to any Sub class
derived from the Super class.
Inheritance is the method of creating the new class based on
already existing class , the new class derived is called Sub class which has
all the features of existing class and its own, i.e sub class.
Adv: Reusability of code , accessibility of variables and methods of the
Base class by the Derived class.
v
P olymorphism: The ability to take more that one form, it
supports Method Overloading & Method
Overriding.
§ Method overloading: When a method in a class having the same
method name with different arguments (diff Parameters or Signatures)
is said to be Method Overloading. This is Compile time Polymorphism.
Using one
identifier to refer to multiple items in the same scope.
§ Method Overriding: When a method in a Class having same method name with same
arguments is said to be Method overriding. This is Run time Polymorphism.
o
Providing
a different implementation of a method in a subclass of the class that
originally defined the method.
1. In Over loading there is a
relationship between the methods available in the same class ,where as in Over
riding there is relationship between the Super class method and Sub class
method.
2. Overloading does not block the Inheritance from the Super
class , Where as in Overriding blocks Inheritance from the Super Class.
3. In Overloading separate methods share
the same name, where as in Overriding Sub class method replaces the
Super Class.
4.
Overloading must have
different method Signatures , Where as Overriding methods must have same
Signatures.
Dynamic dispatch: is a mechanism by which a call to Overridden function is resolved at
runtime rather than at Compile time , and this is how Java implements Run time
Polymorphism.
v D Dynamic Binding: Means the code associated with the given procedure call is not known
until the time of call the call at run time. (it is associated with Inheritance
& Polymorphism).
v e Byte code: Is a optimized set of instructions designed to be
executed by Java-run time system, which is called the Java Virtual machine
(JVM), i.e. in its standard form, the JVM is an Interpreter for byte code.
JIT- is a compiler for Byte code, The
JIT-Complier is part of the JVM, it complies byte code into executable
code in real time, piece-by-piece on demand basis.
Final classes :
String, Integer , Color, Math
Abstract class :
Generic servlet, Number class
o
variable:An item of data named by an identifier.Each variable has a type,such as
int or Object,andascope
o
class
variable :A data item
associated with a particular class as a whole--not with particular instances of
the class. Class variables are defined in class definitions. Also called a static field.
See also instance variable.
o
instance
variable :Any item of
data that is associated with a particular object. Each instance of a class has
its own copy of the instance variables defined in the class. Also called a field. See
also class variable.
o
local
variable :A data item
known within a block, but inaccessible to code outside the block. For example,
any variable defined within a method is a local variable and can't be used
outside the method.
o class method :A method that is invoked without reference to a particular object.
Class methods affect the class as a whole, not a particular instance of the
class. Also called a static
method. also instance
method.
o
instance
method :Any method
that is invoked with respect to an instance of a class. Also called simply a method. See
also class method.