Java学习笔记高级篇01

rcyaw2 · 发表于 31-8-2012 01:54 PM

学习Java三个月，开贴与同样学习著Java的朋友讨论。我安装了三个IDE，NetBeans，Eclipse，JCreator。

以下是个OOP的范列：

// Fig. 10.4: Employee.java
// Employee abstract superclass.
public abstract class Employee implements Payable
{
private String firstName;
private String lastName;
private String socialSecurityNumber;
// three-argument constructor
public Employee( String first, String last, String ssn )
{
firstName = first;
lastName = last;
socialSecurityNumber = ssn;
} // end three-argument Employee constructor
// set first name
public void setFirstName( String first )
{
firstName = first; // should validate
} // end method setFirstName
// return first name
public String getFirstName()
{
return firstName;
} // end method getFirstName
// set last name
public void setLastName( String last )
{
lastName = last; // should validate
} // end method setLastName
// return last name
public String getLastName()
{
return lastName;
} // end method getLastName
// set social security number
public void setSocialSecurityNumber( String ssn )
{
socialSecurityNumber = ssn; // should validate
} // end method setSocialSecurityNumber
// return social security number
public String getSocialSecurityNumber()
{
return socialSecurityNumber;
} // end method getSocialSecurityNumber
// return String representation of Employee object
@Override
public String toString()
{
return String.format( "%s %s\nsocial security number: %s",
getFirstName(), getLastName(), getSocialSecurityNumber() );
} // end method toString
public abstract double earnings();
}
// Fig. 10.8: BasePlusCommissionEmployee.java
// BasePlusCommissionEmployee class extends CommissionEmployee.
public class BasePlusCommissionEmployee extends CommissionEmployee
{
private double baseSalary; // base salary per week
//six-argument constructor
public BasePlusCommissionEmployee( String first, String last,
String ssn, double sales, double rate, double salary )
{
super( first, last, ssn, sales, rate );
setBaseSalary( salary ); // validate and store base salary
} // end six-argument BasePlusCommissionEmployee constructor
// set base salary
public void setBaseSalary( double salary )
{
if ( salary >= 0.0 )
baseSalary = salary;
else
throw new IllegalArgumentException(
"Base salary must be >= 0.0" );
} // end method setBaseSalary
public double getBaseSalary()
{
return baseSalary;
} // end method getBaseSalary
// calculate earnings; override method earnings in CommissionEmployee
@Override
public double earnings()
{
return getBaseSalary() + super.earnings();
} // end method earnings
// 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 method toString
}
// Fig. 10.7: CommissionEmployee.java
// CommissionEmployee class extends Employee.
public class CommissionEmployee extends Employee
{
private double grossSales; // gross weekly sales
private double commissionRate; // commission percentage
// five-argument constructor
public CommissionEmployee( String first, String last, String ssn,
double sales, double rate )
{
super( first, last, ssn );
setGrossSales( sales );
setCommissionRate( rate );
}
// set commission rate
public void setCommissionRate( double rate )
{
if ( rate > 0.0 && rate < 1.0 )
commissionRate = rate;
else
throw new IllegalArgumentException(
"Commission rate must be > 0.0 and < 1.0" );
} // end method setCommissionRate
// return commission rate
public double getCommissionRate()
{
return commissionRate;
} // end method getCommissionRate
// set gross sales amount
public void setGrossSales( double sales )
{
if ( sales >= 0.0 )
grossSales = sales;
else
throw new IllegalArgumentException(
"Gross sales must be >= 0.0" );
} // end method setGrossSales
// return gross sales amount
public double getGrossSales()
{
return grossSales;
} // end method getGrossSales
// calculate earnings; override abstract method earnings in Employee
@Override
public double earnings()
{
return getCommissionRate() * getGrossSales();
} // end method earnings
// 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 method toString
} // end class CommissionEmployee
// Fig. 10.6: HourlyEmployee.java
// HourlyEmployee class extends Employee.
public class HourlyEmployee extends Employee
{
private double wage; // wage per hour
private double hours; // hours worked for week
//five-argument constructor
public HourlyEmployee( String first, String last, String ssn,
double hourlyWage, double hoursWorked )
{
super( first, last, ssn );
setWage( hourlyWage ); // validate hourly wage
setHours( hoursWorked ); // validate hours worked
} // end five-argument HourlyEmployee constructor
// set wage
public void setWage( double hourlyWage )
{
if ( hourlyWage >= 0.0 )
wage = hourlyWage;
else
throw new IllegalArgumentException(
"Hourly wage must be >= 0.0" );
} // end method setWage
// return wage
public double getWage()
{
return wage;
} // end method getWage
// set hours worked
public void setHours( double hoursWorked )
{
if ( ( hoursWorked >= 0.0 ) && ( hoursWorked <= 168.0 ) )
hours = hoursWorked;
else
throw new IllegalArgumentException(
"Hours worked must be >= 0.0 and <= 168.0" );
} // end method setHours
// return hours worked
public double getHours()
{
return hours;
} // end method getHours
// calculate earnings; override abstract method earnings in Employee
@Override
public double earnings()
{
if ( getHours() <= 40 ) // no overtime
return getWage() * getHours();
else
return 40 * getWage() + ( getHours() - 40 ) * getWage() * 1.5;
} // end method earnings
// 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 method toString
}

复制代码

rcyaw2 · 发表于 31-8-2012 01:55 PM

// Fig. 10.12: Invoice.java
// Invoice class that implements Payable.
public class Invoice implements Payable
{
private String partNumber;
private String partDescription;
private int quantity;
private double pricePerItem;
// four-argument constructor
public Invoice( String part, String description, int count,
double price )
{
partNumber = part;
partDescription = description;
setQuantity( count ); // validate and store quantity
setPricePerItem( price ); // validate and store price per item
} // end four-argument Invoice constructor
// set part number
public void setPartNumber( String part )
{
partNumber = part; // should validate
} // end method setPartNumber
// get part number
public String getPartNumber()
{
return partNumber;
} // end method getPartNumber
// set description
public void setPartDescription( String description )
{
partDescription = description; // should validate
} // end method setPartDescription
// get description
public String getPartDescription()
{
return partDescription;
} // end method getPartDescription
// set quantity
public void setQuantity( int count )
{
if ( count >= 0 )
quantity = count;
else
throw new IllegalArgumentException( "Quantity must be >= 0" );
} // end method setQuantity
// get quantity
public int getQuantity()
{
return quantity;
} // end method getQuantity
// set price per item
public void setPricePerItem( double price )
{
if ( price >= 0.0 )
pricePerItem = price;
else
throw new IllegalArgumentException(
"Price per item must be >= 0" );
} // end method setPricePerItem
// get price per item
public double getPricePerItem()
{
return pricePerItem;
} // end method getPricePerItem
// return String representation of Invoice object
@Override
public 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() );
} // end method toString
// method required to carry out contract with interface Payable
@Override
public double getPaymentAmount()
{
return getQuantity() * getPricePerItem(); // calculate total cost
} // end method getPaymentAmount
}
// Fig. 10.11: Payable.java
// Payable interface declaration.
public interface Payable
{
double getPaymentAmount(); // calculate payment; no implementation
} // end interface Payable
// Fig. 10.15: PayableInterfaceTest.java
// Tests interface Payable.
public class PayableInterfaceTest
{
public static void main( String[] args )
{
// create four-element Payable array
Payable[] payableObjects = new Payable[ 4 ];
// populate array with objects that implement Payable
payableObjects[ 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 SalariedEmployee( "Lisa", "Barnes", "888-88-8888", 1200.00 );
System.out.println(
"Invoices and Employees processed polymorphically:\n" );
// generically process each element in array payableObjects
for ( Payable currentPayable : payableObjects )
{
// output currentPayable and its appropriate payment amount
System.out.printf( "%s \n%s: $%,.2f\n\n",
currentPayable.toString(),
"payment due",currentPayable.getPaymentAmount() );
} // end for
} // end main
} // end class PayableInterfaceTest
// Fig. 10.9: PayrollSystemTest.java
// Employee hierarchy test program.
public class PayrollSystemTest
{
public static void main( String[] args )
{
// create subclass objects
SalariedEmployee salariedEmployee =
new SalariedEmployee( "John", "Smith", "111-11-1111", 800.00 );
HourlyEmployee hourlyEmployee =
new HourlyEmployee( "Karen", "Price", "222-22-2222", 16.75, 40 );
CommissionEmployee commissionEmployee =
new CommissionEmployee(
"Sue", "Jones", "333-33-3333", 10000, .06 );
BasePlusCommissionEmployee basePlusCommissionEmployee =
new BasePlusCommissionEmployee(
"Bob", "Lewis", "444-44-4444", 5000, .04, 300 );
System.out.println( "Employees processed individually:\n" );
System.out.printf( "%s\n%s: $%,.2f\n\n",
salariedEmployee, "earned", salariedEmployee.earnings() );
System.out.printf( "%s\n%s: $%,.2f\n\n",
hourlyEmployee, "earned", hourlyEmployee.earnings() );
System.out.printf( "%s\n%s: $%,.2f\n\n",
commissionEmployee, "earned", commissionEmployee.earnings() );
System.out.printf( "%s\n%s: $%,.2f\n\n",
basePlusCommissionEmployee,
"earned", basePlusCommissionEmployee.earnings() );
Employee[] employees = new Employee[ 4 ];
// initialize array with Employees
employees[ 0 ] = salariedEmployee;
employees[ 1 ] = hourlyEmployee;
employees[ 2 ] = commissionEmployee;
employees[ 3 ] = basePlusCommissionEmployee;
System.out.println( "Employees processed polymorphically:\n" );
// generically process each element in array employees
for ( Employee currentEmployee : employees )
{
System.out.println(currentEmployee ); // invokes toString
// determine whether element is a BasePlusCommissionEmployee
if ( currentEmployee instanceof BasePlusCommissionEmployee)
{
// downcast Employee reference to
// BasePlusCommissionEmployee reference
BasePlusCommissionEmployee employee =
(BasePlusCommissionEmployee) currentEmployee;
employee.setBaseSalary( 1.10 * employee.getBaseSalary() );
System.out.printf(
"new base salary with 10%% increase is: $%,.2f\n",
employee.getBaseSalary() );
} // end if
System.out.printf( "earned $%,.2f\n\n",currentEmployee.earnings() );
} // end for
// get type name of each object in employees array
for ( int j = 0; j < employees.length; j++ )
System.out.printf( "Employee %d is a %s\n", j,
employees[ j ].getClass().getName() );
}
}
// Fig. 10.5: SalariedEmployee.java
// SalariedEmployee concrete class extends abstract class Employee.
public class SalariedEmployee extends Employee
{
private double weeklySalary;
// four-argument constructor
public SalariedEmployee( String first, String last, String ssn,
double salary )
{
super( first, last, ssn ); // pass to Employee constructor
setWeeklySalary( salary ); // validate and store salary
} // end four-argument SalariedEmployee constructor
// set salary
public void setWeeklySalary( double salary )
{
if ( salary >= 0.0 )
weeklySalary = salary;
else
throw new IllegalArgumentException(
"Weekly salary must be >= 0.0" );
} // end method setWeeklySalary
// return salary
public double getWeeklySalary()
{
return weeklySalary;
} // end method getWeeklySalary
// calculate earnings; override abstract method earnings in Employee
@Override
public double getPaymentAmount()
{
return getWeeklySalary();
} // end method getPaymentAmount
@Override
public double earnings()
{
return getWeeklySalary();
} // end method earnings
// 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 method toString
}

复制代码

jasonmun · 发表于 31-8-2012 09:13 PM

NetBeans，Eclipse，JCreator
其实还有一个叫RAD的.. 是 EClipse 的分支..
需要安装到3个没? 懂用一个, 知道它的理论.. 其实其它都一样的..
不同的是软件UI不一样而已, 骨子还是一样..

懂 OOP 只是JAVA的基础.. 或其它第4代电脑语言的基础..
有时间研究 Design Patterns 才是王道..

BakaYY_Ling · 发表于 16-11-2012 02:02 PM

jasonmun 发表于 31-8-2012 09:13 PM
NetBeans，Eclipse，JCreator
其实还有一个叫RAD的.. 是 EClipse 的分支..
需要安装到3个没? 懂用一个, 知 ...

想问大大~~ 爬了很多帖~~
看到很多人讨论OOP~~ 也大概知道这东西~
可是~~怎样才能学习OOP阿？
我本身是读E-commerce 的~~
想问~~我应不应该学习java呢？基础属否不一样？

jasonmun · 发表于 16-11-2012 02:38 PM

BakaYY_Ling 发表于 16-11-2012 02:02 PM
想问大大~~ 爬了很多帖~~
看到很多人讨论OOP~~ 也大概知道这东西~
可是~~怎样才能学习OOP阿？

1. 懂了OOP的概念, 就多看别人的 coding. 自然你就会熟悉.. 知道怎样写与用它..
2. 学不学 JAVA, 跟你念的没有关系.. 而是看你有没有兴趣去学.

zblue89 · 发表于 16-11-2012 05:53 PM

学不学 JAVA, 跟你念的没有关系.. 而是看你有没有兴趣去学.

+1，赞成。

加峻 · 发表于 16-11-2012 10:57 PM

不好意思...
我是java新手。
请问，lz的笔记是怎么样参考？

		自动登录	找回密码
密码			注册

Java学习笔记高级篇01

相关帖子

所属分类: 电脑手机

浏览过的版块