public class Variable{

    static int allClicks=0;    // 类变量

    String str="hello world";  // 实例变量

    public void method(){

        int i =0;  // 局部变量

    }

}

public class Test{

   public void pupAge(){

      int age = 0;

      age = age + 7;

      System.out.println("小狗的年龄是: " + age);

   }

   public static void main(String[] args){

      Test test = new Test();

      test.pupAge();

   }

}

public class Test{

   public void pupAge(){

      int age;

      age = age + 7;

      System.out.println("小狗的年龄是 : " + age);

   }

   public static void main(String[] args){

      Test test = new Test();

      test.pupAge();

   }

}

import java.io.*;

public class Employee{

   // 这个实例变量对子类可见

   public String name;

   // 私有变量，仅在该类可见

   private double salary;

   //在构造器中对name赋值

   public Employee (String empName){

      name = empName;

   }

   //设定salary的值

   public void setSalary(double empSal){

      salary = empSal;

   }

   // 打印信息

   public void printEmp(){

      System.out.println("名字 : " + name );

      System.out.println("薪水 : " + salary);

   }

   public static void main(String[] args){

      Employee empOne = new Employee("RUNOOB");

      empOne.setSalary(1000);

      empOne.printEmp();

   }

}

import java.io.*;

public class Employee {

    //salary是静态的私有变量

    private static double salary;

    // DEPARTMENT是一个常量

    public static final String DEPARTMENT = "开发人员";

    public static void main(String[] args){

    salary = 10000;

        System.out.println(DEPARTMENT+"平均工资:"+salary);

    }

}