克拉玛依网站建设/网站结构优化的内容和方法

接口代表了一种设计规范，同继承、多态一样，也是一种很重要的面向对象编程思想。

程序功能：

本程序在多态处理不同类型员工的工资的基础上，让基类Employee实现Payable接口，从而可以将员工工资的处理操作与应付款（如，采购款的支付）操作进行合并。从而，在更高层次实现系统的重用性。

类图如下，其中，除SalariedEmpolyee外，HourlyEmployee, ComissionEmployee也继承了Employee类。另外，BasePlusComissionEmployee继承ComissionEmployee。

测试结果：

测试代码：

1. 测试类

//Java How to Program, Exercise 10.15: Accounts Payable System Modification
//by pandenghuang@163.com
/*** 10.15 (Accounts Payable System Modification) In this exercise, we modify the* accounts payable application of Figs. 10.11–10.15 to include the complete* functionality of the payroll application of Figs. 10.4–10.9. The application* should still process two Invoice objects, but now should process one object* of each of the four Employee subclasses. If the object currently being* processed is a Base- PlusCommissionEmployee, the application should increase* the BasePlusCommissionEmployee’s base salary by 10%. Finally, the application* should output the payment amount for each object. Complete the following* steps to create the new application: a) Modify classes HourlyEmployee (Fig.* 10.6) and CommissionEmployee (Fig. 10.7) to place them in the Payable* hierarchy as subclasses of the version of Employee (Fig. 10.13) that* implements Payable. [Hint: Change the name of method earnings to* getPaymentAmount in each subclass so that the class satisfies its inherited* contract with interface Payable.] b) Modify class BasePlusCommissionEmployee* (Fig. 10.8) such that it extends the version of class CommissionEmployee* created in part (a). c) Modify PayableInterfaceTest (Fig. 10.15) to* polymorphically process two Invoices, one SalariedEmployee, one* HourlyEmployee, one CommissionEmployee and one Base- PlusCommissionEmployee.* First output a String representation of each Payable object. Next, if an* object is a BasePlusCommissionEmployee, increase its base salary by 10%.* Finally, output the payment amount for each Payable object.* * @author Pandenghuang@163.com* @Date Jan 7, 2019, 2:07:26 PM**/
public class PayableInterfaceTest 
{public static void main(String[] args){// create four-element Payable arrayPayable[] payableObjects = new Payable[6];// populate array with objects that implement PayablepayableObjects[0] = new Invoice("01234", "seat", 2, 375.00);payableObjects[1] = new Invoice("56789", "tire", 4, 79.95);payableObjects[2] = new SalariedEmployee("John", "Smith", "111-11-1111", 800.00);payableObjects[3] = new HourlyEmployee("Lisa", "Barnes", "888-88-8888", 40,50);payableObjects[4] = new CommissionEmployee("Andrew", "Brown", "999-99-9999", 100000,0.08);payableObjects[5] = new BasePlusCommissionEmployee("Andy", "Jobs", "666-66-6666", 100000.0,0.08,600.0);System.out.println("Invoices and Employees processed polymorphically:"); // generically process each element in array payableObjectsfor (Payable currentPayable : payableObjects){// output currentPayable and its appropriate payment amountSystem.out.printf("%n%s %n%s: $%,.2f%n", currentPayable.toString(), // could invoke implicitly"payment due", currentPayable.getPaymentAmount()); // determine whether element is a BasePlusCommissionEmployeeif (currentPayable instanceof BasePlusCommissionEmployee) {// downcast Employee reference to // BasePlusCommissionEmployee referenceBasePlusCommissionEmployee employee = (BasePlusCommissionEmployee) currentPayable;employee.setBaseSalary(1.10 * employee.getBaseSalary());System.out.printf("new base salary with 10%% increase is: $%,.2f",employee.getBaseSalary());} } } // end main
} // end class PayableInterfaceTest

2. 实体类

1）Payable接口

// Fig. 10.11: Payable.java
// Payable interface declaration.public interface Payable 
{    double getPaymentAmount(); // calculate payment; no implementation
}

2） Invoice类

// Fig. 10.12: Invoice.java
// Invoice class that implements Payable.public class Invoice implements Payable
{private final String partNumber; private final String partDescription;private int quantity;private double pricePerItem;// constructorpublic Invoice(String partNumber, String partDescription, int quantity,double pricePerItem){if (quantity < 0) // validate quantitythrow new IllegalArgumentException("Quantity must be >= 0");if (pricePerItem < 0.0) // validate pricePerItemthrow new IllegalArgumentException("Price per item must be >= 0");this.quantity = quantity;this.partNumber = partNumber;this.partDescription = partDescription;this.pricePerItem = pricePerItem;} // end constructor// get part numberpublic String getPartNumber(){return partNumber; // should validate} // get descriptionpublic String getPartDescription(){return partDescription;} // set quantitypublic void setQuantity(int quantity){if (quantity < 0) // validate quantitythrow new IllegalArgumentException("Quantity must be >= 0");this.quantity = quantity;} // get quantitypublic int getQuantity(){return quantity;}// set price per itempublic void setPricePerItem(double pricePerItem){if (pricePerItem < 0.0) // validate pricePerItemthrow new IllegalArgumentException("Price per item must be >= 0");this.pricePerItem = pricePerItem;} // get price per itempublic double getPricePerItem(){return pricePerItem;} // return String representation of Invoice object@Overridepublic String toString(){return String.format("%s: %n%s: %s (%s) %n%s: %d %n%s: $%,.2f", "invoice", "part number", getPartNumber(), getPartDescription(), "quantity", getQuantity(), "price per item", getPricePerItem());} // method required to carry out contract with interface Payable     @Override                                                           public double getPaymentAmount()                                    {                                                                   return getQuantity() * getPricePerItem(); // calculate total cost} 
} // end class Invoice

3). Employee类

// Fig. 10.13: Employee.java
// Employee abstract superclass that implements Payable.public abstract class Employee implements Payable
{private final String firstName;private final String lastName;private final String socialSecurityNumber;// constructorpublic Employee(String firstName, String lastName, String socialSecurityNumber){this.firstName = firstName;this.lastName = lastName;this.socialSecurityNumber = socialSecurityNumber;} // return first namepublic String getFirstName(){return firstName;} // return last namepublic String getLastName(){return lastName;} // return social security numberpublic String getSocialSecurityNumber(){return socialSecurityNumber;} // return String representation of Employee object@Overridepublic String toString(){return String.format("%s %s%nsocial security number: %s", getFirstName(), getLastName(), getSocialSecurityNumber());}// Note: We do not implement Payable method getPaymentAmount here so // this class must be declared abstract to avoid a compilation error.
} // end abstract class Employee

4). SalariedEmployee类

// Fig. 10.14: SalariedEmployee.java
// SalariedEmployee class that implements interface Payable.
// method getPaymentAmount.
public class SalariedEmployee extends Employee 
{private double weeklySalary;// constructorpublic SalariedEmployee(String firstName, String lastName, String socialSecurityNumber, double weeklySalary){super(firstName, lastName, socialSecurityNumber); if (weeklySalary < 0.0)throw new IllegalArgumentException("Weekly salary must be >= 0.0");this.weeklySalary = weeklySalary;} // set salarypublic void setWeeklySalary(double weeklySalary){if (weeklySalary < 0.0)throw new IllegalArgumentException("Weekly salary must be >= 0.0");this.weeklySalary = weeklySalary;} // return salarypublic double getWeeklySalary(){return weeklySalary;} // calculate earnings; implement interface Payable method that was// abstract in superclass Employee                                @Override                                                         public double getPaymentAmount()                                  {                                                                 return getWeeklySalary();                                      } // return String representation of SalariedEmployee object   @Override                                                    public String toString()                                     {                                                            return String.format("salaried employee: %s%n%s: $%,.2f",super.toString(), "weekly salary", getWeeklySalary());} 
} // end class SalariedEmployee

5). HourlyEmployee类

// Fig. 10.6: HourlyEmployee.java
// HourlyEmployee class extends Employee.public class HourlyEmployee extends Employee 
{private double wage; // wage per hourprivate double hours; // hours worked for week// constructorpublic HourlyEmployee(String firstName, String lastName,String socialSecurityNumber, double wage, double hours){super(firstName, lastName, socialSecurityNumber);if (wage < 0.0) // validate wagethrow new IllegalArgumentException("Hourly wage must be >= 0.0");if ((hours < 0.0) || (hours > 168.0)) // validate hoursthrow new IllegalArgumentException("Hours worked must be >= 0.0 and <= 168.0");this.wage = wage;this.hours = hours;} // set wagepublic void setWage(double wage){if (wage < 0.0) // validate wagethrow new IllegalArgumentException("Hourly wage must be >= 0.0");this.wage = wage;} // return wagepublic double getWage(){return wage;} // set hours workedpublic void setHours(double hours){if ((hours < 0.0) || (hours > 168.0)) // validate hoursthrow new IllegalArgumentException("Hours worked must be >= 0.0 and <= 168.0");this.hours = hours;} // return hours workedpublic double getHours(){return hours;} // calculate earnings; override abstract method earnings in Employee@Override                                                           public double getPaymentAmount()                                            {                                                                   if (getHours() <= 40) // no overtime                           return getWage() * getHours();                                else                                                             return 40 * getWage() + (getHours() - 40) * getWage() * 1.5;}                                          // return String representation of HourlyEmployee object              @Override                                                             public String toString()                                              {                                                                     return String.format("hourly employee: %s%n%s: $%,.2f; %s: %,.2f",super.toString(), "hourly wage", getWage(),                     "hours worked", getHours());                                   }                                    
} // end class HourlyEmployee

6）CommissionEmployee类

public class CommissionEmployee extends Employee 
{private double grossSales; // gross weekly salesprivate double commissionRate; // commission percentage// constructorpublic CommissionEmployee(String firstName, String lastName,String socialSecurityNumber,  double grossSales, double commissionRate){super(firstName, lastName,socialSecurityNumber);if (commissionRate <= 0.0 || commissionRate >= 1.0) // validate throw new IllegalArgumentException("Commission rate must be > 0.0 and < 1.0");if (grossSales < 0.0) // validatethrow new IllegalArgumentException("Gross sales must be >= 0.0");this.grossSales = grossSales;this.commissionRate = commissionRate;} // set gross sales amountpublic void setGrossSales(double grossSales){if (grossSales < 0.0) // validatethrow new IllegalArgumentException("Gross sales must be >= 0.0");this.grossSales = grossSales;} // return gross sales amountpublic double getGrossSales(){return grossSales;} // set commission ratepublic void setCommissionRate(double commissionRate){if (commissionRate <= 0.0 || commissionRate >= 1.0) // validatethrow new IllegalArgumentException("Commission rate must be > 0.0 and < 1.0");this.commissionRate = commissionRate;} // return commission ratepublic double getCommissionRate(){return commissionRate;} // calculate earnings; override abstract method earnings in Employee@Override                                                           public double getPaymentAmount()                                            {                                                                   return getCommissionRate() * getGrossSales();                    }                                             // return String representation of CommissionEmployee object@Override                                                   public String toString()                                    {                                                           return String.format("%s: %s%n%s: $%,.2f; %s: %.2f",    "commission employee", super.toString(),              "gross sales", getGrossSales(),                       "commission rate", getCommissionRate());             } 
} // end class CommissionEmployee

. 7) BasePlusComissionEmployee类

// Fig. 10.8: BasePlusCommissionEmployee.java
// BasePlusCommissionEmployee class extends CommissionEmployee.public class BasePlusCommissionEmployee extends CommissionEmployee 
{private double baseSalary; // base salary per week// constructorpublic BasePlusCommissionEmployee(String firstName, String lastName, String socialSecurityNumber,  double grossSales,double commissionRate, double baseSalary){super(firstName, lastName, socialSecurityNumber, grossSales, commissionRate);if (baseSalary < 0.0) // validate baseSalary                  throw new IllegalArgumentException("Base salary must be >= 0.0");this.baseSalary = baseSalary;                }// set base salarypublic void setBaseSalary(double baseSalary){if (baseSalary < 0.0) // validate baseSalary                  throw new IllegalArgumentException("Base salary must be >= 0.0");this.baseSalary = baseSalary;                } // return base salarypublic double getBaseSalary(){return baseSalary;}// calculate earnings; override method earnings in CommissionEmployee@Override                                                            public double getPaymentAmount()                                             {                                                                    return getBaseSalary() + super.getPaymentAmount();                        } // return String representation of BasePlusCommissionEmployee object@Override                                                           public String toString()                                            {                                                                   return String.format("%s %s; %s: $%,.2f",                       "base-salaried", super.toString(),                            "base salary", getBaseSalary());                             } 
} // end class BasePlusCommissionEmployee