Java note (6) static keywords, static keywords

Java note (6) static keywords, static keywords

Static keywords:

Package com. dingding. staticdemo; class Person {String name;Private static String country = "Beijing ";Public Person (String name) {this. name = name;} public static String getCountry () {return country;} public static void setCountry (String country) {Person. country = country;} public void tell () {System. out. println ("name:" + name + "Birthplace:" + country) ;}} public class StaticDemo01 {public static void main (String [] args ){Person. setCountry ("Shanghai ");// Class method (static) is generally used when all instance objects are of the same value. Person p1 = new Person ("Zhang San"); p1.tell (); person p2 = new Person ("Li Si"); p2.tell (); Person p3 = new Person ("Wang Wu"); p3.tell ();}}

 

Running result:

Name: zhangsan Birthplace: Shanghai
Name: Li Si Birthplace: Shanghai
Name: Wang Wu Birthplace: Shanghai

 

Analysis:

1. Class methods and static variables are generally used when the instance objects used are of the same value.

2. In the main () method, the Code Person. setCountry ("Shanghai"); declares static state, so it must be called before instantiation.

3. Features of class variables: all objects and classes share this property.