Java SE 23rd talk----the static keyword

1.static keyword "30 minutes to start teaching in 22-speaking video"

2.static decorated properties: No matter how many objects a class generates, all of these objects work together to use a unique static member variable, and one object modifies that static member variable, and the value of that static member variable for the other object changes as well. If a member variable is static, then we can use it in the same way as the class name. Member variable (Java recommends this way).

 Package com.cl.abstracttest;  Public class statictest {    publicstaticvoid  main (string[] args) {        new  mystatic ();         New mystatic ();         = ten;        System.out.println (mystatic2.a);    }} class mystatic{     int  A;}

The result is: 0

change int A to static int a the result becomes 10.

 package   Com.cl.abstracttest;  public  class   Statictest { static  void   main (string[] args) {MyS        Tatic mystatic  =  mystatic (); MYSTATIC.A  = 10; //  Use the class name directly. Member Variable mode              System.out.println (MYSTATIC.A); }}  class   mystatic{ static  int   A;}  

3.static Modification Method: The static method is called a method. For static methods, you can use the class name. Method name to access

 Packagecom.cl.staticandfinal; Public classStaticTest2 { Public Static voidMain (string[] args) {/*method One MyStatic2 s = new MyStatic2 (); S.output ();*/                //Method Twomystatic2.output ();//need to change method to static}}classmystatic2{ Public  Static voidoutput () {System.out.println ("Output"); }}

4. static methods can only inherit and cannot be overridden (override). subclasses cannot override parent class methods and can overload parent class methods

 Packagecom.cl.staticandfinal; Public classStaticTest3 { Public Static voidMain (string[] args) {m M=NewN ();    M.output (); }     }classm{ Public  Static voidoutput () {System.out.println (M); }}classNextendsm{ Public Static voidoutput () {System.out.println (N); }}
The output is: M
If you put

M m = new n (); instead n m = new n (); The result is n

5.final Keyword: Final can modify properties, methods, classes.

6.final Modified class: When a class is modified by final, it means that the class is a final state class and cannot be inherited.

Java SE 23rd talk----the static keyword