个人觉的不可理解.....以下是原话然而,尽管在Manager类中没有显式地的定义getName和getHireDay等方法,但属于Manager类的对象却可以使用它们,这是因为Manager类自动地继承了超类Employee中的这些方法。
同样,从超类中还继承了name,salary和hireDay这3个域。这样一来,每个Manager类对象就包括了4个域:name,salary,hireDay和bonus.代码如下/**
@version 1.21 2004-02-21
@author Cay Horstmann
*/import java.util.*;public class ManagerTest
{
public static void main(String[] args)
{
// construct a Manager object
Manager boss = new Manager("Carl Cracker", 80000, 1987, 12, 15);
boss.setBonus(5000); Employee[] staff = new Employee[3]; // fill the staff array with Manager and Employee objects staff[0] = boss;
staff[1] = new Employee("Harry Hacker", 50000, 1989, 10, 1);
staff[2] = new Employee("Tommy Tester", 40000, 1990, 3, 15); // print out information about all Employee objects
for (Employee e : staff)
System.out.println("name=" + e.getName()
+ ",salary=" + e.getSalary());
}
}class Employee
{
public Employee(String n, double s, int year, int month, int day)
{
name = n;
salary = s;
GregorianCalendar calendar = new GregorianCalendar(year, month - 1, day);
hireDay = calendar.getTime();
} public String getName()
{
return name;
} public double getSalary()
{
return salary;
} public Date getHireDay()
{
return hireDay;
} public void raiseSalary(double byPercent)
{
double raise = salary * byPercent / 100;
salary += raise;
} private String name;
private double salary;
private Date hireDay;
}class Manager extends Employee
{
/**
@param n the employee's name
@param s the salary
@param year the hire year
@param month the hire month
@param day the hire day
*/
public Manager(String n, double s, int year, int month, int day)
{
super(n, s, year, month, day);
bonus = 0;
} public double getSalary()
{
double baseSalary = super.getSalary();
return baseSalary + bonus;
} public void setBonus(double b)
{
bonus = b;
} private double bonus;
}
居然说私有域也被继承了。。后面又花了点时间解释,怎么可能?
同样,从超类中还继承了name,salary和hireDay这3个域。这样一来,每个Manager类对象就包括了4个域:name,salary,hireDay和bonus.代码如下/**
@version 1.21 2004-02-21
@author Cay Horstmann
*/import java.util.*;public class ManagerTest
{
public static void main(String[] args)
{
// construct a Manager object
Manager boss = new Manager("Carl Cracker", 80000, 1987, 12, 15);
boss.setBonus(5000); Employee[] staff = new Employee[3]; // fill the staff array with Manager and Employee objects staff[0] = boss;
staff[1] = new Employee("Harry Hacker", 50000, 1989, 10, 1);
staff[2] = new Employee("Tommy Tester", 40000, 1990, 3, 15); // print out information about all Employee objects
for (Employee e : staff)
System.out.println("name=" + e.getName()
+ ",salary=" + e.getSalary());
}
}class Employee
{
public Employee(String n, double s, int year, int month, int day)
{
name = n;
salary = s;
GregorianCalendar calendar = new GregorianCalendar(year, month - 1, day);
hireDay = calendar.getTime();
} public String getName()
{
return name;
} public double getSalary()
{
return salary;
} public Date getHireDay()
{
return hireDay;
} public void raiseSalary(double byPercent)
{
double raise = salary * byPercent / 100;
salary += raise;
} private String name;
private double salary;
private Date hireDay;
}class Manager extends Employee
{
/**
@param n the employee's name
@param s the salary
@param year the hire year
@param month the hire month
@param day the hire day
*/
public Manager(String n, double s, int year, int month, int day)
{
super(n, s, year, month, day);
bonus = 0;
} public double getSalary()
{
double baseSalary = super.getSalary();
return baseSalary + bonus;
} public void setBonus(double b)
{
bonus = b;
} private double bonus;
}
居然说私有域也被继承了。。后面又花了点时间解释,怎么可能?
解决方案 »
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