Java超详细讲解类变量和类方法

package com.demo.static_;

import java.sql.SQLOutput;

public class childgeme {

     public static void main(String[] args) {

         Child ch01= new Child( "牛牛牛" );

         ch01.join();

         ch01.count++;

         Child ch02= new Child( "马马马" );

         ch02.join();

         ch02.count++;

         Child ch03= new Child( "猪猪猪" );

         ch03.join();

         ch03.count++;

         System.out.println( "共有" +Child.count+ "个小孩加入了游戏" );

         System.out.println( "ch01.count=" +ch01.count);

         System.out.println( "ch02.count=" +ch02.count);

         System.out.println( "ch03.count=" +ch03.count);

     }

}

class Child{

     private String name;

     //定义一个变量count，是一个类变量（静态变量）

     public static int count= 0 ;

     public Child(String name) {

         this .name = name;

     }

     public String getName() {

         return name;

     }

     public void setName(String name) {

         this .name = name;

     }

     public static int getCount() {

         return count;

     }

     public static void setCount( int count) {

         Child.count = count;

     }

     public void join(){

         System.out.println( this .name+ "加入了游戏" );

     }

}

package com.demo.static_;

import java.sql.SQLOutput;

public class visit_Static {

     public static void main(String[] args) {

         //1.类名.类变量名

         //static类变量在类加载的时候就生成使用

         System.out.println( "A.name=" +A.name);

         System.out.println( "A.getAge()=" +A.getAge());

         //2.类对象.类变量名

         A a= new A();

         System.out.println( "a.name=" +a.name);

         System.out.println( "a.getAge()=" +a.getAge());

     }

}

class A{

     //类变量

     public static String name= "Demo龙" ;

     private static int age= 99 ;

     public static int getAge() {

         return age;

     }

     public static void setAge( int age) {

         A.age = age;

     }

}

package com.demo.static_;

public class static_method {

     public static void main(String[] args) {

         stu a01= new stu( "小虎" );

         //stu.sumfee();

         a01.sumfee( 150 );

         stu a02= new stu( "小龙" );

         a02.sumfee( 250 );

         //stu.sumfee();

         stu a03= new stu( "小猪" );

         stu.sumfee( 199 );

         //输出当前收到的总学费

         stu.showfee();

     }

}

class stu{

     private String name; //普通成员

     //定义一个静态变量来累计学生的学费

     private static double fee= 0 ;

     public stu(String name) {

         this .name = name;

     }

     public String getName() {

         return name;

     }

     public void setName(String name) {

         this .name = name;

     }

     //当方法使用了static修饰后，该方法就是静态方法

     //静态方法就可以访问静态变量

     public static double getFee() {

         return fee;

     }

     public static void setFee( double fee) {

         stu.fee = fee;

     }

     public static void sumfee( double fee){

         stu.fee+=fee;

     }

     public static void showfee(){

         System.out.println( "总学费=" +stu.fee);

     }

}