2019/0521/抽象類別+介面

#java 抽象類別

函式名稱與()就直接分號了 不會提供{}內實作

###沒有完全的實作，子類別也必須宣告為抽象的

Why can't static methods be abstract in Java?Stack Overflow

類別 繼承 多型 抽象類別

在架構上概念上擴展 員工這個案例 employee

接著實作整個架構的內容

實作抽象類別

###Employee.java

###SalariedEmployee.java

###HourlyEmployee.java

###CommissionEmployee.java

###BasePlusCommissionEmployee.java

###PayrollSystemTest.java

###/Hello World/src/abstractClass/Employee.java

package abstractClass;

public abstract class Employee extends Object{
	
	   private final String firstName;                        
	   private final String lastName;                         
	   private final String idNumber;             
	                                
	   public Employee(String firstName, String lastName, String idNumber)
	   {                                                                  
	      super();

	      this.firstName = firstName;                                     
	      this.lastName = lastName;                                    
	      this.idNumber = idNumber;         
	   } 

	   public String getFirstName()
	   {
	      return firstName;
	   }

	   public String getLastName()
	   {
	      return lastName;
	   } 

	   public String getIdNumber()
	   {
	      return idNumber;
	   } 

       public abstract double earnings();              

	   @Override
	   public String toString()                                             
	   {                                                                    
	      return String.format("%s: %s %s%n%s: %s%n" ,    
	         "員工姓名", getFirstName(), getLastName(),                    
	         "身分證字號", getIdNumber());                           
	   } 

}

###/Hello World/src/abstractClass/CommissionEmployee.java

package abstractClass;

public class CommissionEmployee extends Employee{
	
       private double grossSales; 
	   private double commissionRate; // 佣金，抽庸的比例
	                                
	   public CommissionEmployee(String firstName, String lastName, String idNumber, double grossSales, double commissionRate)
	   {                                                                  
	      super(firstName,lastName,idNumber);
		   
		  if (grossSales < 0.0) 
	         throw new IllegalArgumentException("銷售金額必須 >= 0.0");

	      if (commissionRate <= 0.0 || commissionRate >= 1.0)
	         throw new IllegalArgumentException("佣金比例必須 > 0.0 and < 1.0");
     
	      this.grossSales = grossSales;
	      this.commissionRate = commissionRate;
	   } 

	   public void setGrossSales(double grossSales)
	   {
	      if (grossSales < 0.0) 
	         throw new IllegalArgumentException("銷售金額必須 >= 0.0");

	      this.grossSales = grossSales;
	   } 

	   public double getGrossSales()
	   {
	      return grossSales;
	   } 

	   public void setCommissionRate(double commissionRate)
	   {
	      if (commissionRate <= 0.0 || commissionRate >= 1.0)
	         throw new IllegalArgumentException("佣金比例必須 > 0.0 and < 1.0");

	      this.commissionRate = commissionRate;
	   } 

	   public double getCommissionRate()
	   {
	      return commissionRate;
	   } 
	   
	   @Override
	   public double earnings()              
	   {                                     
	      return getCommissionRate() * getGrossSales();
	   } 

	   @Override
	   public String toString()                                             
	   {                                                                    
	      return String.format("%s%n%s: %.2f%n%s: %.2f %n%s: %.2f" ,    
	         super.toString(),                
	         "銷售金額", getGrossSales(),                                     
	         "佣金比例", getCommissionRate(),
	         "總佣金",getCommissionRate() * getGrossSales());                           
	   } 

}

###/Hello World/src/abstractClass/BasePlusCommissionEmployee.java

package abstractClass;

public class BasePlusCommissionEmployee extends CommissionEmployee {

	private double baseSalary; // 底薪

	public BasePlusCommissionEmployee(String firstName, String lastName, String idNumber, double grossSales,double commissionRate, double baseSalary) {
		super(firstName, lastName, idNumber, grossSales, commissionRate);

		if (baseSalary < 0.0)
			throw new IllegalArgumentException("底薪金額必須 >= 0.0");

		this.baseSalary = baseSalary;
	}

	public void setBaseSalary(double baseSalary) {
		if (baseSalary < 0.0)
			throw new IllegalArgumentException("底薪金額必須 >= 0.0");

		this.baseSalary = baseSalary;
	}

	public double getBaseSalary() {
		return baseSalary;
	}

	@Override
	public double earnings() {
		return getBaseSalary() + (super.getCommissionRate() * super.getGrossSales());
	}

	@Override
	public String toString() {
	      return String.format("%s %n %s: %.2f%n %s: %.2f" ,    
	 	         super.toString(),
	 	         "底薪金額", getBaseSalary(),
	 	         "底薪+獎金  金額", this.earnings());
	}

}

###/Hello World/src/abstractClass/WeekSalaryPlusCommissionEmployee.java

package abstractClass;

public class WeekSalaryPlusCommissionEmployee extends CommissionEmployee {

	private double weekSalary; // 周薪

	public WeekSalaryPlusCommissionEmployee(String firstName, String lastName, String idNumber, double grossSales,double commissionRate, double weekSalary) {
		super(firstName, lastName, idNumber, grossSales, commissionRate);

		if (weekSalary < 0.0)
			throw new IllegalArgumentException("周薪金額必須 >= 0.0");

		this.weekSalary = weekSalary;
	}

	public void setWeekSalary(double weekSalary) {
		if (weekSalary < 0.0)
			throw new IllegalArgumentException("周薪金額必須 >= 0.0");

		this.weekSalary = weekSalary;
	}

	public double getWeekSalary() {
		return weekSalary;
	}

	@Override
	public double earnings() {
		return getWeekSalary() + (super.getCommissionRate() * super.getGrossSales());
	}

	@Override
	public String toString() {
	      return String.format("%s%n %s %n%s: %.2f%n %s: %.2f" , "領周薪加獎金的員工",   
	 	         super.toString(),  "周薪金額", getWeekSalary(),"周薪+獎金  金額", this.earnings() );
	}

}

###/Hello World/src/abstractClass/PaySystemTest.java

package abstractClass;

public class PaySystemTest {

	public static void main(String[] args) {
		
		BasePlusCommissionEmployee employee01 = new BasePlusCommissionEmployee("劉", "德華", "A123456789", 10000, .06,1000);
		CommissionEmployee employee02 = new CommissionEmployee("陳", "立農", "A123456789", 50000, .1);
		WeekSalaryPlusCommissionEmployee employee03 = new WeekSalaryPlusCommissionEmployee ("韓", "國魚", "A333333333", 2000, .05, 500);
		
		System.out.printf("%n%s:%n%n%s%n", "第 1 位員工薪資資料", employee01.toString());
		System.out.printf("%n%s:%n%n%s%n", "第 2 位員工薪資資料", employee02.toString());
		System.out.printf("%n%s:%n%n%s%n", "第 3 位員工薪資資料", employee03.toString());
	}

}

到這裡還沒有多型的應用只是類別繼承抽象類別，等等會講應用

剛剛是抽傭的員工(commission employee)

接著要做 時薪員工 ( hourly employee )

###HourlyEmployee.java

package abstractClass;

public class HourlyEmployee extends Employee {

	private double wage;
	private double hours; // 工時

	public HourlyEmployee(String firstName, String lastName, String idNumber, double wage, double hours) {
		super(firstName, lastName, idNumber);

		if (wage < 0.0)
			throw new IllegalArgumentException("時薪必須 >= 0.0");

		if (hours <= 0.0 || hours >= 720.0)
			throw new IllegalArgumentException("工作時數必須 > 0.0 and < 720.0");

		this.wage = wage;
		this.hours = hours;
	}

	public void setWage(double wage) {
		if (wage < 0.0)
			throw new IllegalArgumentException("時薪必須 >= 0.0");

		this.wage = wage;
	}

	public double getWage() {
		return wage;
	}

	public void setHours(double hours) {
		if (hours <= 0.0 || hours >= 720.0)
			throw new IllegalArgumentException("工作時數必須 > 0.0 and < 720.0");
		this.hours = hours;
	}

	public double getHours() {
		return hours;
	}

	@Override
	public double earnings() {
		if (getHours() <= 40)
			return getHours() * getWage();
		else
			return (40 * getWage()) + ((getHours() - 40) * (getWage() * 1.5));
	}

	@Override
	public String toString() {
		return String.format("%s%n%s: %.2f%n%s: %.2f %n%s: %.2f", super.toString(), "單位時薪", getWage(), "工作時數",
				getHours(), "總時薪", this.earnings());
	}

}

接著做Salaried employee 固定薪資員工

###Salaried employee.java

package abstractClass;

public class SalariedEmployee extends Employee {

	private double salary; //薪資

	public SalariedEmployee(String firstName, String lastName, String idNumber, double salary) {
		super(firstName, lastName, idNumber);

		if (salary < 0.0)
			throw new IllegalArgumentException("薪資必須 >= 0.0");

		this.salary = salary;
	}

	public void setSalary(double salary) {
		if (salary < 0.0)
			throw new IllegalArgumentException("薪資必須 >= 0.0");
		this.salary = salary;
	}

	public double getSalary() {
		return salary;
	}

	@Override
	public double earnings() {
	    return getSalary();
	
	}

	@Override
	public String toString() {
		return String.format("%s%n%s: %.2f", super.toString(), "固定薪資", this.earnings());
	}

}

針對底薪加獎金的員工做加薪動作

做再

### PaySystemTest.java

package abstractClass;

public class PaySystemTest {

	public static void main(String[] args) {
		
		BasePlusCommissionEmployee employee01 = new BasePlusCommissionEmployee("劉", "德華", "A123456789", 10000, .06,1000);
		CommissionEmployee employee02 = new CommissionEmployee("陳", "立農", "A123456789", 50000, .1);
		WeekSalaryPlusCommissionEmployee employee03 = new WeekSalaryPlusCommissionEmployee("韓", "國魚", "A333333333", 2000, .05, 500);
		HourlyEmployee employee04 = new HourlyEmployee("方", "大同", "A1111111111", 150, 60);
		
//		System.out.printf("%n%s:%n%n%s%n", "第 1 位員工薪資資料", employee02.toString());
//		System.out.printf("%n%s:%n%n%s%n", "第 2 位員工薪資資料", employee01.toString());
//		System.out.printf("%n%s:%n%n%s%n", "第 3 位員工薪資資料", employee03.toString());
//		System.out.printf("%n%s:%n%n%s%n", "第 4 位員工薪資資料", employee04.toString());
		
		Employee empArray[] = new Employee[7];
		empArray[0] = employee01;
		empArray[1] = employee02;
		empArray[2] = employee03;
		empArray[3] = employee04;
		empArray[4] = new SalariedEmployee("周", "潤發", "A2222222222", 55000.0);
		empArray[5] = new BasePlusCommissionEmployee("李", "連杰", "A444444444", 20000, .06,2000);
		empArray[6] = new BasePlusCommissionEmployee("郭", "富城", "A555555555", 10000, .06,3000);
				
				
		for(int i = 0; i < empArray.length ;i++)
		{
			System.out.printf("%n%s%d%s:%n%n%s%n", "第 ",i+1," 位員工薪資資料", empArray[i].toString());		
		}

		
		for(int i = 0,j=0; i < empArray.length ;i++)
		{
			if (empArray[i] instanceof BasePlusCommissionEmployee)
			{
				((BasePlusCommissionEmployee)empArray[i]).setBaseSalary(1.1 * ((BasePlusCommissionEmployee)empArray[i]).getBaseSalary());
				System.out.printf("%n%s%d%s:%n%n%s%n", "第 ",j+1," 位領底薪+獎金員工，加薪10%後薪資資料", empArray[i].toString());		
				j++;
			}
		}
		
		
	}

}

剛剛幾種類別之間都有繼承關係 員工 ( 各種不同的員工

子類別必須要是一種父類別

不管是領時薪或領月薪的員工都是員工

#介面 interface

之前階段?有接觸

都是算錢 但是無繼承關係 所以就要使用介面

##概論

彼此之間有關係 就用抽象類別 做繼承

但類別之間沒有繼承關係 ( 進貨單 並不是一種員工

這種時候就要使用 interface 介面

##實作

##它的架構跟抽象類別有點像

抽象方法 定義有繼承關係的類別

介面 定義無繼承關係的類別

##實作介面 payable

記得介面裡面不可以有任何實體變數與方法

抽象類別可以實作但沒時做的就必須繼續抽像宣告下去

Employee.java 內

getPaymentAmount() 要取代原本的earnings()

但在這個地方還是

沒辦法實作 getPaymentAmount()

所以只要 implements Payable{}

再將earnings() 刪除即可

即可

接著實作 CommissionEmployee.java

只要將earnings() 改為 getPaymentAmount() 即可

做個InterfaceTest.java來測試

介面操作多型期時跟抽象類別操作多型類似

指是乘載的父輩變介面類別

記得介面裡面不可以有任何實體變數與方法

##抽象類別與介面 ( 精神上不一樣 ( 但實作上架構類似

做完了Payable 與 employee 與 salaried employee

接著

實作 Invoice

材料編號 材料敘述 單價 數量

##建構式也是在限制變數範圍

##然後方法則是一些算式

https://blog.51cto.com/lavasoft/18771blog.51cto.com

final 說明

###Payable.java

package interfaceClass;

public interface Payable {
	
	public abstract double getPaymentAmount();

}

###Employee.java

package interfaceClass;

public abstract class Employee extends Object implements Payable{
	
	   private final String firstName;                        
	   private final String lastName;                         
	   private final String idNumber;             
	                                
	   public Employee(String firstName, String lastName, String idNumber)
	   {                                                                  
	      super();

	      this.firstName = firstName;                                     
	      this.lastName = lastName;                                    
	      this.idNumber = idNumber;         
	   } 

	   public String getFirstName()
	   {
	      return firstName;
	   }

	   public String getLastName()
	   {
	      return lastName;
	   } 

	   public String getIdNumber()
	   {
	      return idNumber;
	   } 

	   @Override
	   public String toString()                                             
	   {                                                                    
	      return String.format("%s: %s %s%n%s: %s%n" ,    
	         "員工姓名", getFirstName(), getLastName(),                    
	         "身分證字號", getIdNumber());                           
	   } 

}

###CommissionEmployee.java

package interfaceClass;

public class CommissionEmployee extends Employee{
	
       private double grossSales; 
	   private double commissionRate; // 佣金，抽庸的比例
	                                
	   public CommissionEmployee(String firstName, String lastName, String idNumber, double grossSales, double commissionRate)
	   {                                                                  
	      super(firstName,lastName,idNumber);
		   
		  if (grossSales < 0.0) 
	         throw new IllegalArgumentException("銷售金額必須 >= 0.0");

	      if (commissionRate <= 0.0 || commissionRate >= 1.0)
	         throw new IllegalArgumentException("佣金比例必須 > 0.0 and < 1.0");
     
	      this.grossSales = grossSales;
	      this.commissionRate = commissionRate;
	   } 

	   public void setGrossSales(double grossSales)
	   {
	      if (grossSales < 0.0) 
	         throw new IllegalArgumentException("銷售金額必須 >= 0.0");

	      this.grossSales = grossSales;
	   } 

	   public double getGrossSales()
	   {
	      return grossSales;
	   } 

	   public void setCommissionRate(double commissionRate)
	   {
	      if (commissionRate <= 0.0 || commissionRate >= 1.0)
	         throw new IllegalArgumentException("佣金比例必須 > 0.0 and < 1.0");

	      this.commissionRate = commissionRate;
	   } 

	   public double getCommissionRate()
	   {
	      return commissionRate;
	   } 
	   
	   public double getPaymentAmount()              
	   {                                     
	      return getCommissionRate() * getGrossSales();
	   } 

	   @Override
	   public String toString()                                             
	   {                                                                    
	      return String.format("%s%n%s: %.2f%n%s: %.2f %n%s: %.2f" ,    
	         super.toString(),                
	         "銷售金額", getGrossSales(),                                     
	         "佣金比例", getCommissionRate(),
	         "總佣金",getCommissionRate() * getGrossSales());                           
	   } 

}

###SalariedEmployee.java

package interfaceClass;

public class SalariedEmployee extends Employee {

	private double salary; //薪資

	public SalariedEmployee(String firstName, String lastName, String idNumber, double salary) {
		super(firstName, lastName, idNumber);

		if (salary < 0.0)
			throw new IllegalArgumentException("薪資必須 >= 0.0");

		this.salary = salary;
	}

	public void setSalary(double salary) {
		if (salary < 0.0)
			throw new IllegalArgumentException("薪資必須 >= 0.0");
		this.salary = salary;
	}

	public double getSalary() {
		return salary;
	}

	@Override
	public double getPaymentAmount() {
	    return getSalary();
	
	}

	@Override
	public String toString() {
		return String.format("%s%n%s: %.2f", super.toString(), "固定薪資", this.getPaymentAmount());
	}

}

###WeekSalaryPlusCommissionEmployee.java

package interfaceClass;

public class WeekSalaryPlusCommissionEmployee extends CommissionEmployee {

	private double weekSalary; // 周薪

	public WeekSalaryPlusCommissionEmployee(String firstName, String lastName, String idNumber, double grossSales,double commissionRate, double weekSalary) {
		super(firstName, lastName, idNumber, grossSales, commissionRate);

		if (weekSalary < 0.0)
			throw new IllegalArgumentException("周薪金額必須 >= 0.0");

		this.weekSalary = weekSalary;
	}

	public void setWeekSalary(double weekSalary) {
		if (weekSalary < 0.0)
			throw new IllegalArgumentException("周薪金額必須 >= 0.0");

		this.weekSalary = weekSalary;
	}

	public double getWeekSalary() {
		return weekSalary;
	}

	@Override
	public double getPaymentAmount() {
		return getWeekSalary() + (super.getCommissionRate() * super.getGrossSales());
	}

	@Override
	public String toString() {
	      return String.format("%s%n %s %n%s: %.2f%n %s: %.2f" , "領周薪加獎金的員工",   
	 	         super.toString(),  "周薪金額", getWeekSalary(),
	 	         "周薪+獎金  金額", this.getPaymentAmount());
	}

}

###Invoic.java

package interfaceClass;

public class Invoice implements Payable {

	private final String partNumber; // 材料編號
	private final String partDescription; // 材料敘述
	private double pricePerItem; // 單價
	private int quantity; // 數量

	public Invoice(String partNumber, String partDescription, int quantity, double pricePerItem) {
		super();

		if (quantity < 0.0)
			throw new IllegalArgumentException("貨務數量必須 >= 0.0");

		if (pricePerItem < 0.0)
			throw new IllegalArgumentException("貨物單價必須 >= 0.0");

		this.partNumber = partNumber;
		this.partDescription = partDescription;
		this.quantity = quantity;
		this.pricePerItem = pricePerItem;
	}

	public String getPartNumber() {
		return partNumber;
	}

	public String getPartDescription() {
		return partDescription;
	}

	public void setQuantity(int quantity) {
		if (quantity < 0.0)
			throw new IllegalArgumentException("貨務數量必須 >= 0.0");

		this.quantity = quantity;
	}

	public double getQuantity() {
		return quantity;
	}

	public void setPricePerItem(double pricePerItem) {
		if (pricePerItem < 0.0)
			throw new IllegalArgumentException("貨物單價必須 >= 0.0");

		this.pricePerItem = pricePerItem;
	}

	public double getPricePerItem() {
		return pricePerItem;
	}

	@Override
	public double getPaymentAmount() {
		return getQuantity() * getPricePerItem();
	}
	
	  @Override
	   public String toString()                                             
	   {                                                                    
	      return String.format("%s: %s%n%s: %s%n%s: %.2f%n%s: %.2f %n%s: %.2f" ,    
	         "貨物編號", getPartNumber(),                
	         "貨物描述", getPartDescription(),                                     
	         "數量", getQuantity(),
	         "單價", getPricePerItem(),
	         "總金額",this.getPaymentAmount());                           
	   } 

}

###InterfaceTest.java

package interfaceClass;

public class InterfaceTest {

	public static void main(String[] args) {
		// TODO 自動產生的方法 Stub

//		Employee empArray[] = new Employee[7];
		
		Payable payableInterfaceArray[] = new Payable[4]; 
		
		payableInterfaceArray[0] = new CommissionEmployee("陳", "立農", "A123456789", 50000, .1);
		payableInterfaceArray[1] = new SalariedEmployee("周", "潤發", "A2222222222", 55000.0);
		payableInterfaceArray[2] = new WeekSalaryPlusCommissionEmployee("韓", "國魚", "A333333333", 2000, .05, 500);
		payableInterfaceArray[3] = new Invoice("P0001", "雨衣", 3, 100.0);
		
		for(int i = 0; i < payableInterfaceArray.length ;i++)
		{
			System.out.printf("%n%s%d%s:%n%n%s%n", "第 ",i+1," 筆，應付款資料", payableInterfaceArray[i].toString());		
		}
	}

}