Re: accessing java bean's property

From:

Daniel Pitts <newsgroup.spamfilter@virtualinfinity.net>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 18 Mar 2010 14:21:02 -0700

Message-ID:

<ZOwon.116235$0N3.99734@newsfe09.iad>

On 3/17/2010 5:49 PM, Arne Vajh?j wrote:

On 17-03-2010 18:50, Daniel Pitts wrote:

On 3/16/2010 6:56 PM, Arne Vajh?j wrote:

On 12-03-2010 20:52, Daniel Pitts wrote:

On 3/12/2010 5:29 PM, Arne Vajh?j wrote:

On 12-03-2010 11:25, Daniel Pitts wrote:

On 3/12/2010 6:02 AM, angelochen960@gmail.com wrote:

I have this bean:

public class Item {
private String type;
private Boolean pub;

This should probably be a "boolean", not a Boolean.

public String getType() { return type;}

public Boolean isPub() { return pub;}

Same as above. Boolean is an object reference type, which may end up
being null. Most of the time, you don't want a null for a boolean
value.
This is true of most of the primitive types.

Data classes frequently have the requirement to support
null for data not available or not applicable.

Which is why I used the phrase "Most of the time" as opposed to "All of
the time".

In my experience, it is more common for someone mistakenly choose a
wrapper than for someone meaningfully choose a wrapper. It is also less
common that someone mistakenly chooses a primitive over a wrapper.

Data classes and CRUD are a big part of IT.

And choosing a wrapper unnecessary have very small consequences
while mistakenly choosing a primitive is a real data integrity
problem.

I believe the opposite of your statement is true. Or at least some
compromise.

CRUD may be a big part of IT, but null values for every field are
required for well formed CRUD. Choosing a wrapper unnecessarily can lead
to NPE's or null-checks through-out code. Primitives guarantee non-null
values.

My point is to use a type which most closely matches your requirements.
If you really have a use-case where NULL is an acceptable and expected
value, then by all means use a wrapper. Otherwise you are asking for
trouble.

NULL/null is a very frequent valid value in real world data. Lack
of information is common.

It may be common, but not universal.
   1. Some data is required for a meaningful record.
   2. Some data may be inferred from other data if not otherwise specified.
   3. Some data may have a "sensible default".

Those types of data should be non-nullable to ensure data consistency.

--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>