Java

1-Feb-11 0:06

Hey!

I'm trying to refactor some code, bringing some style in.

I stumbled over an expression I can not explain at all:

if ((aParent == null) || ((parent = this.getParent(aParent.getLabel())) == null)) {
    // do not use variable parent
}
else{
    // use parent
}

can anyone explain this? I tried to cahnge it 3 times, but failed totally Frown | :(

regards
Torsten

I never finish anyth...

Richard MacCutchan1-Feb-11 1:15

1-Feb-11 1:15

Does this do it?

parent = null;
if (aParent != null)
    parent = this.getParent(aParent.getLabel());
if (aParent == null || parent == null) {
    // do not use variable parent
}
else{
    // use parent
}

I must get a clever new signature for 2011.

TorstenH.1-Feb-11 1:47

1-Feb-11 1:47

right - this was also my first thought. However - this is not functional.
I also tried some other variations (invert it, bias variable parent, ...) - all failed.
the problem I'm facing here might be completely on another class - who knows Confused | :confused:

Strange little bit of codestyle warning - but not my biggest problem on the project.

regards
Torsten

I never finish anyth...

Message Closed

1-Feb-11 3:29

User 1138000

1-Feb-11 3:29

Message Closed

modified 21-Nov-20 21:01pm.

TorstenH.1-Feb-11 3:58

1-Feb-11 3:58

this doesn't make any difference. parent is null - no matter if it is set to null or not initialized at all.
Imho it's just a question of style and code reliability, more important on values like String or some number values.

Anyway, I have some more bugs in the code, need to add something like a "architecture" (I'm scared of that working package since I took over the project and brought the point up...) and - first topic on list - is to push out a deployment for the customer.

I'll let you all know how I massacred this little piece of code when I head back to that one.

regards
Torsten

I never finish anyth...

Richard MacCutchan1-Feb-11 4:14

1-Feb-11 4:14

TorstenH. wrote:
this doesn't make any difference. parent is null - no matter if it is set to null or not initialized at all.

Not quite; there is a difference between an uninitialised object and one that is explicitly set to null.

I must get a clever new signature for 2011.

TorstenH.1-Feb-11 5:29

1-Feb-11 5:29

Oh come on - that was way back when hamsters wheels where needed to get the machine started!!

The JVM takes care of not initialized stuff. It sets every not initialized object to null, every boolean to false, ...

Object Initialization in Java[^]

regards
Torsten

I never finish anyth...

Richard MacCutchan1-Feb-11 5:52

1-Feb-11 5:52

Really? My java compiler does not seem to have read that article:

C:\Users\Richard\Documents\eclipse>javac BaseTest.java
BaseTest.java:16: variable parent might not have been initialized
        if (aParent == null || parent == null) {
                               ^
1 error

I must get a clever new signature for 2011.

TorstenH.1-Feb-11 23:54

1-Feb-11 23:54

yeah - and then I realized how time flew by. I updated my runtime from V1.0 to V6 and got aware of the eclipse project...

regards
Torsten

I never finish anyth...

jschell1-Feb-11 10:55

1-Feb-11 10:55

TorstenH. wrote:
The JVM takes care of not initialized stuff. It sets every not initialized object to null, every boolean to false, ...

No it doesn't.

It provides a default initialization for class member variables.

That is not the case for local variables. The compiler is responsible for flagging uninitialized locals as errors.

Richard MacCutchan1-Feb-11 3:51

1-Feb-11 3:51

TorstenH. wrote:
However - this is not functional.

Strang,e it works fine for me; perhaps there is something else that you have not explained.

I must get a clever new signature for 2011.

TorstenH.1-Feb-11 4:03

1-Feb-11 4:03

there is something else that you have not explained.

perhaps something I didn't catch on Sigh | :sigh:

regards
Torsten

I never finish anyth...

how to solve?

pancakeleh31-Jan-11 19:32

pancakeleh

31-Jan-11 19:32

when a button was being clicked, this screenshot as shown below occurs. what does the screenshot below tells?

http://img822.imageshack.us/img822/7673/httperror.png[^]

Re: how to solve?

Richard MacCutchan31-Jan-11 22:09

Android Application Start

31-Jan-11 22:09

The message is reasonably clear; the HTTP server encountered an error which is recorded in the server logs.

I must get a clever new signature for 2011.

MsmVc31-Jan-11 19:02

MsmVc

31-Jan-11 19:02

Hi All

I use adb command for install .apk file in java,it's run successfully and install in android phone.Now i want to start application automatically when application is install successfully.Please help me

Query XML Via JDBC

Zig15831-Jan-11 5:15

Zig158

31-Jan-11 5:15

I have a reporting application pulls in data via a JDBC connection and fills my report. It can use any standard JDBC driver that supports Prepared Statements. I now have the need to query XML files directly. Does anyone have any suggestions on a JDBC driver that will read an XML File? What I am looking for is an XML equivalent to CSVJDBC.

So far I have found two options that don't fit my situation very well.
StelsXML - Looks promising but this project currently has no budget.
Ashpool - Open source license. Looks abandon and still has major issues.

jschell31-Jan-11 11:21

31-Jan-11 11:21

Zig158 wrote:
I now have the need to query XML files directly.

There are of course ways to extract information from XML data which have nothing to do with JDBC.

Zig1581-Feb-11 9:03

Zig158

1-Feb-11 9:03

Yes I could extract the XML data to a database and then query it from there. I am trying to avoid this because it will require changes to the process that I do not control. The goal is the load the XML file like a table the same way CSVJDBC lets you load a CSV file like a table.

jschell1-Feb-11 10:30

1-Feb-11 10:30

Zig158 wrote:
Yes I could extract the XML data to a database and then query it from there.

Could.

That however has nothing do to with what I said however.

Zig158 wrote:
The goal is the load the XML file like a table the same way CSVJDBC lets you load a CSV file like a table.

I am going to presume at this point that you know nothing about the available APIs suited to accessing XML. Following is some background.

http://en.wikipedia.org/wiki/Document_Object_Model[^]

You should then google for resources on using XML in java.

David Skelly1-Feb-11 22:28

David Skelly

1-Feb-11 22:28

Did you read his question?

He has an existing reporting tool that uses JDBC. He would like to use that reporting tool to access data in XML format.

His question is: is there any JDBC driver that will allow him to use the reporting tool directly on the XML data? Failing that, he could extract the XML into a database and then run the reporting tool over that, but he would rather not.

He is not asking about how to manipulate XML data. He is asking how to read XML through JDBC because that is the constraint he has in place with his reporting tool.

jschell2-Feb-11 8:19

2-Feb-11 8:19

David Skelly wrote:
He has an existing reporting tool that uses JDBC. He would like to use that reporting tool to access data in XML format.

I missed that.

jschell2-Feb-11 8:22

2-Feb-11 8:22

Zig158 wrote:
Does anyone have any suggestions on a JDBC driver that will read an XML File?

Now that it was pointed out that that I misread your question...

What is the complexity level of the report -> xml interface?

If it isn't too significant then one option would be to write your own JDBC driver. Put only the functionality you need into it. Something like a select with some simple where clauses isn't that difficult to convert into a xpath with the result set spanning the result of that.

Zig1584-Feb-11 7:54

Zig158

4-Feb-11 7:54

I was hopeful that I could avoid writing something custom/new, but it sounds like that is the case. I could rewrite the reader interface for CSVJDBC.

jschell4-Feb-11 9:30