startup code
 

Is there any way to add code to a class that will get executed whenever the program starts up?

(i.e. without explicitly calling into it)

Re: startup code
 

On Tue, 28 Aug 2012 11:48:41 -0700 (PDT), bob smith
<bob@coolfone.comze.com> wrote, quoted or indirectly quoted someone
who said :

>Is there any way to add code to a class that will get executed whenever the program starts up?

You can put in it the main method or in a static init block.

See http://mindprod.com/jgloss/static.html
--
Roedy Green Canadian Mind Products http://mindprod.com
A new scientific truth does not triumph by convincing its opponents and making them see the light,
but rather because its opponents eventually die, and a new generation grows up that is familiar with it.
~ Max Planck 1858-04-23 1947-10-04

Re: startup code
 

On 08/28/2012 02:48 PM, bob smith wrote:
> Is there any way to add code to a class that will get executed whenever the program starts up?
>
> (i.e. without explicitly calling into it)
<http://www.nofluffjuststuff.com/blog/vladimir_vivien/2011/10/loader_launcher__a_pattern_to_bootstrap_java_appli cations>

Re: startup code
 

On Tuesday, August 28, 2012 11:53:34 AM UTC-7, Roedy Green wrote:
> bob smith wrote, quoted or indirectly quoted someone who said :
>>Is there any way to add code to a class that will get executed whenever the program starts up?
>
> You can put in it the main method or in a static init block.
> See http://mindprod.com/jgloss/static.html

The main method technique will happen whenever the program starts up.

The class init block won't run until the class is initialized (not necessarily
when it's loaded). This can be quite a while after the program starts "up".
It can even be quite a while after the class is loaded.

--
Lew

Re: startup code
 

On 28.08.2012 23:00, Lew wrote:
> On Tuesday, August 28, 2012 11:53:34 AM UTC-7, Roedy Green wrote:
>> bob smith wrote, quoted or indirectly quoted someone who said :
>>> Is there any way to add code to a class that will get executed whenever the program starts up?
>>
>> You can put in it the main method or in a static init block.
>> See http://mindprod.com/jgloss/static.html
>
> The main method technique will happen whenever the program starts up.
>
> The class init block won't run until the class is initialized (not necessarily
> when it's loaded). This can be quite a while after the program starts "up".
> It can even be quite a while after the class is loaded.

Still it is often early enough, i.e. before instances of the very class
get to do their work.

Bob, what are you trying to accomplish? Or is this more like a homework
question?

Kind regards

robert

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

Re: startup code
 

Robert Klemme wrote:
> Lew wrote:
> ...
>> The class init block won't run until the class is initialized (not necessarily
>> when it's loaded). This can be quite a while after the program starts "up".
>> It can even be quite a while after the class is loaded.
>
> Still it is often early enough, i.e. before instances of the very class
> get to do their work.

"Early enough" depends on whether the OP wants what they literally asked for,
something that happens at program start, or the more relaxed requirement of
before the class is otherwise used.

> Bob, what are you trying to accomplish? Or is this more like a homework
> question?

Bob, this is a key question Robert asks.

--
Lew

Re: startup code
 

On 8/28/2012 2:48 PM, bob smith wrote:
> Is there any way to add code to a class that will get executed whenever the program starts up?
>
> (i.e. without explicitly calling into it)

Create a new class with a main that:
- does whatever you want done
- calls the original main
and run that.

Arne

Re: startup code
 

On 8/28/2012 2:53 PM, Roedy Green wrote:
> On Tue, 28 Aug 2012 11:48:41 -0700 (PDT), bob smith
> <bob@coolfone.comze.com> wrote, quoted or indirectly quoted someone
> who said :
>> Is there any way to add code to a class that will get executed whenever the program starts up?
>
> You can put in it the main method or in a static init block.

That does not run code when the program startup.

It will run the code when the class is first loaded.

Which may not even happen.

Arne

Re: startup code
 

Arne Vajhøj wrote:
> Roedy Green wrote:
>> bob smith wrote, quoted or indirectly quoted someone who said :
>>> Is there any way to add code to a class that will get executed wheneverthe program starts up?
>
>> You can put in it the main method or in a static init block.
>
> That does not run code when the program startup.
> It will run the code when the class is first loaded.

No.

It will run the code when the class is initialized, which might
be considerably after the class is first loaded.

> Which may not even happen.

Same with initialization - a class might be loaded and never
initialized.

--
Lew

Re: startup code
 

On Tue, 28 Aug 2012 14:00:47 -0700 (PDT), Lew <lewbloch@gmail.com>
wrote, quoted or indirectly quoted someone who said :

>
>The class init block won't run until the class is initialized

I think he means by "the program" the class name invoked on the
command line. In that case the static init blocks in that class will
execute even before the main method.

Under what conditions does a class load without running the static
init blocks?
--
Roedy Green Canadian Mind Products http://mindprod.com
A new scientific truth does not triumph by convincing its opponents and making them see the light,
but rather because its opponents eventually die, and a new generation grows up that is familiar with it.
~ Max Planck 1858-04-23 1947-10-04