Subject: Var access question... 2006-11-01 - By Duc Vo
Back
I don't fully agree with Tim though. The idea is only true when you have
attributes as primitive or simple object type. With complex object type
or expensive-to-create type, getters (private or not) are much better
for says lazy initialization or unit testing, also make your code much
cleaner.
Duc
-- --Original Message-- --
From: A mailing list for Java(tm) 2 Platform, Enterprise Edition
[mailto:J2EE-INTEREST@(protected)] On Behalf Of Tim Wood
Sent: Thursday, 2 November 2006 7:10 AM
To: J2EE-INTEREST@(protected)
Subject: Re: Var access question...
I'll probably get flak for this BUT... :)
Defining and using getters for private state just adds needless
indirection and makes the resulting Java even more function-call
intensive. I still like the naming convention approach:
public class ComplexNumber {
private double m_real;
private double m_imaginary;
...
public double magnitude() {
return (Math.sqrt(Math.pow(m_real, 2)
+ Math.pow(m_imaginary, 2)));
}
...
}
This clearly distinguishes members from locals, and lets method code
work concisely with private data. Tools like checkstyle can enforce the
convention. I agree having member names look like local names can be
confusing. In the event that the method body needs to be moved away
from the state it touches, accessors will be needed. The naming
convention makes it easy to safely change the references to accessors,
if you don't have an IDE to do the refactoring for you.
HTH,
TW
At 10:43 AM 11/01/06, Karr, David wrote:
>I often implement private getters for properties that should only be
>accessed from within the class. I like to keep local variables and
>instance variables semantically apart, to emphasize that instance
>variables should only be declared if they're really necessary.
>
>> -- --Original Message-- --
>> From: A mailing list for Java(tm) 2 Platform, Enterprise
>> Edition [mailto:J2EE-INTEREST@(protected)] On Behalf Of Ne'Bahn
>> Sent: Tuesday, October 31, 2006 4:59 AM
>> To: J2EE-INTEREST@(protected)
>> Subject: Var access question...
>>
>> Hi list, I'm wondering if it's a good practice to access
>> fields (in the same class) through its names and not by its
>> accessors, e.g.
>>
>> public class ComplexNumber {
>> private double U;
>> private double V;
>>
>> // constructor deleted
>>
>> public double real() {
>> return U;
>> }
>>
>> public double imaginary() {
>> return V;
>> }
>>
>> public double magnitude() {
>> return (Math.sqrt(Math.pow(U, 2) + Math.pow(V, 2)));
>> // access here must be U or real(), same with V }
>>
>> public double arg() throws ArithmeticException {
>> return (Math.atan(V / U));
>> // access here must be U or real(), same with V }
>>
>> public ComplexNumber times(ComplexNumber Z) {
>> return new ComplexNumber(U * Z.U - V * Z.V, U * Z.V + V * Z.U); }
}
>>
>> I think it accomplish to OOP rules (encapsulation), the
>> object itself manages its state interacting with its fields
>> and no other can change their properties, but I've seen many
>> samples that use getters methods to access values, I don't
>> know why...any clue ??? ...
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