// Polymorphism
Definition: means a polymorphic reference can point to the listed listed
Java
Remotely rewriting and rewriting and method overloading
// extends
By joining in the class's statement
Extends
Subsets to create a subclass of a class
Subclasses can inherit the access to the parent class to set to
Public, protected, friendly
Member variables and methods, but cannot inherit access
Private
Member variables and methods.
// final
class
Final
Class cannot be inherited
If you think a class definition is perfect, you don't need to regenerate it into its subclasses. At this time, it should also be modified as
Final
class
Final class classname {...} // Abstract
class
Abstract
Class must be inherited, the method must be overloaded
;
It should not be subjected to an object
Number
Be a
Abstract
class
; // java.lang.object
class
1.equals ():
Compare status and functionality
Integer One = New Integer (1), Anotherone = New Integer (1); IF (One.Equal ("" "Objects Are Equal");} // Return True 2.getClass ()
Yes
Final
method,
Void PrintClassName (Object Obj) {System.out.println ("The Object's Class Is" Obj.getClass (). getName ();)
Create an instance of a class, the object created can be any class
Object CreateNewsTanceOf (Object Obj) {retuen obj.getClass (). Newinstance ();} 3.toString ()
Returns the string of the object
System.Out.println (Thread.currentThread (). Tostring ()); 4.Finalize (); 5.Notify (), NotifyAll (), Wait ()
Synchronization in multi-threaded
//
Member variables
A static:
Class variable
B final:
constant
C Volatile:
Shared variable
//
Member method
A static
: No need to be resembled
(
Class member
)
Others
(
Instance member
); B ABSTRACE
with
Final,
Whether it is overloaded
(
Can you
C Native:
Put
Java
Code and other languages code integrate
D synchronized:
Control multiple concurrent threads to shared data
E throwsexceptionList
:
; F this:
Quote the current object
G super:
Quote the parent class of the current object,
Its usage:
(1) Super.variable //
Use to access the parent class hidden member variables
(2) Super.method ([paramlist]) //
Method used to call the overloaded parent class
(3) Super. ([Paramlist]) //
Call the constructor in the parent class
,
In the class method
(static)
,can not be used
THIS
or
Super
Modifier
// interface
Is a collection of method definitions and constant values
A
The same behavior of the irrelevant class can be achieved by the interface without considering the hierarchical relationship between these classes.
; B
The method of multiple classes need to be implemented by an interface can be indicated.
C
You can understand the interactive interface of the object by an interface without having to understand the class corresponding to the object.
Java
Multiple inheritance
(
A class can be a subclass of multiple classes
)
, Realize its multiple inheritance with an interface. In the state of the class
IMPLEMENTS
To indicate a class to use an interface, you can use the constant defined in the interface and all methods defined in the interface must be implemented. A class can implement multiple interfaces, separated by ",".
