Groups > comp.lang.java.programmer > #38323

Re: Need to modify a legacy closed app

From	Arne Vajhøj <arne@vajhoej.dk>
Newsgroups	comp.lang.java.programmer
Subject	Re: Need to modify a legacy closed app
Date	2018-05-31 20:32 -0400
Organization	Aioe.org NNTP Server
Message-ID	<peq471$jqi$1@gioia.aioe.org> (permalink)
References	<v9ttgdld4tiodnldauf1eid79jgdnd61pl@4ax.com> <peniiv$aje$1@gioia.aioe.org> <vplvgd5f36lidfqhfvmtrjmp2esvh8d22l@4ax.com>

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On 5/31/2018 7:15 AM, Michael Keith wrote:
> On Wed, 30 May 2018 21:19:29 -0400, Arne Vajhøj <arne@vajhoej.dk>
> wrote:
>> On 5/30/2018 3:38 PM, Michael Keith wrote:
>>> I am tasked with modifying a legacy app which consists of an .exe file
>>> and several hundred .jar files. Is is launched by starting the .exe,
>>> which then - somehow - initialises the whole darn thing. This presents
>>> the first difficulty, as I have no idea what the 'main' .jar file is.
>>
>> Check if you have the source code and build scripts somewhere.
>>
>> Yes => change code, rebuild, test and deploy.
>>
>> No =>
>>
>> 1) Check if you have legal right to reverse engineer and modify code.
>> 2) Get a Java decompiler and generate source code from the Java byte code.
>> 3) change code, rebuild, test and deploy.

> No, we don't have the sources. As for the legal stuff that's my boss'
> concern.
> I know of java decompilers, but looking at the sheer number of .jar
> files I was hoping for a short-cut.
> Any other idea maybe?

Maybe the name of the main GUI jar file reveal what it is.

Maybe that jar files manifest has a Main-Class directive.

You can also try moving the jar files one by one and see
when the EXE can no longer start the GUI.

But even if you are lucky and find that then you will still
need to decompile classes in that jar file.

Arne

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Thread

Need to modify a legacy closed app Michael Keith <mjkeith@gmx.de> - 2018-05-30 21:38 +0200
  Re: Need to modify a legacy closed app Arne Vajhøj <arne@vajhoej.dk> - 2018-05-30 21:19 -0400
    Re: Need to modify a legacy closed app Michael Keith <mjkeith@gmx.de> - 2018-05-31 13:15 +0200
      Re: Need to modify a legacy closed app Martin Gregorie <martin@mydomain.invalid> - 2018-05-31 21:50 +0000
      Re: Need to modify a legacy closed app Arne Vajhøj <arne@vajhoej.dk> - 2018-05-31 20:32 -0400

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