package com.cn.base;/* 文件名 : Employee.java *//*抽象类总结规定1. 抽象类不能被实例化(初学者很容易犯的错)，如果被实例化，就会报错，编译无法通过。只有抽象类的非抽象子类可以创建对象。2. 抽象类中不一定包含抽象方法，但是有抽象方法的类必定是抽象类。3. 抽象类中的抽象方法只是声明，不包含方法体，就是不给出方法的具体实现也就是方法的具体功能。4. 构造方法，类方法（用static修饰的方法）不能声明为抽象方法。5. 抽象类的子类必须给出抽象类中的抽象方法的具体实现，除非该子类也是抽象类。*/public abstract class Employee {private String name;private String address;private int number;public Employee(String name, String address, int number) {System.out.println("Constructing an Employee");this.name = name;this.address = address;this.number = number;} public abstract void abstractMethod();public double computePay() {System.out.println("Inside Employee computePay");return 0.0;}public void mailCheck() {System.out.println("Mailing a check to " + this.name + " " + this.address);}public String toString() {return name + " " + address + " " + number;}public String getName() {return name;}public String getAddress() {return address;}public void setAddress(String newAddress) {address = newAddress;}public int getNumber() {return number;}}
package com.cn.base;/* 文件名 : Salary.java * * 我们能通过一般的方法继承Employee类： * */public class Salary extends Employee {private double salary; // Annual salarypublic Salary(String name, String address, int number, double salary) {super(name, address, number);setSalary(salary);}public void mailCheck() {System.out.println("Within mailCheck of Salary class ");System.out.println("Mailing check to " + getName() + " with salary " + salary);}public double getSalary() {return salary;}public void setSalary(double newSalary) {if (newSalary >= 0.0) {salary = newSalary;}}public double computePay() {System.out.println("Computing salary pay for " + getName());return salary / 52;}@Overridepublic void abstractMethod() { //继承抽象类，一定要实现抽象类的抽象方法 System.out.println("我已经实现了该抽象方法！！！");}}
package com.cn.base;/* 文件名 : AbstractDemo.java */public class AbstractDemo {public static void main(String[] args) {Employee e = new Employee("George W.", "Houston, TX", 43);System.out.println("\n Call mailCheck using Employee reference--");e.mailCheck();/** * 当你尝试编译AbstractDemo类时，会产生如下错误：抽象类是不能被实例化的 Employee.java:46: Employee is abstract; cannot be instantiated Employee e = new Employee("George W.", "Houston, TX", 43); 1 error */Salary s = new Salary("Mohd Mohtashim", "Ambehta, UP", 3, 3600.00);Employee e1 = new Salary("John Adams", "Boston, MA", 2, 2400.00);System.out.println("Call mailCheck using Salary reference --");s.mailCheck();System.out.println("\n Call mailCheck using Employee reference--");e.mailCheck();/** * 尽管我们不能实例化一个Employee类的对象， * 但是如果我们实例化一个Salary类对象， * 该对象将从Employee类继承3个成员变量和7个成员方法。 */}}
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