私有变量和私有方法（Example4_15和Example4_16）

public class Example4_15{
 private int money;
 Example4_15(){
  money=2000;
 }
 private int getMoney(){
  return money;
 }
 public static void main(String arg[]){
  Example4_15 exa=new Example4_15();
  exa.money=3000;
  int m=exa.getMoney();
  System.out.println("money="+m);
 }
}

class Employee{  private double salary=1800;

 public void setSalary(double salary){

  if(salary>1800&&salary<=6000){   

 this.salary=salary;   }

 }  

public double getSalary(){

  return salary;  }

}

public class Example4_16{

 public static void main(String arg[]){  

 Employee zhang=new Employee();  

 Employee wang=new Employee();  

 zhang.setSalary(100);

  System.out.println("zhang的薪水:"+zhang.getSalary());  

 wang.setSalary(3888);   

System.out.println("wang的薪水:"+wang.getSalary());  }

}