Multi Project Build

Help/Discuss
1

I am working on migrating a Huge project from Maven3 to Gradle.

Is it possible to reduce the compilation time in Gradle by detecting the changes done (while development) to a particular project in Multi Project build and compile only that project without explicitly asking it to do???

Is there any way to achieve this in Gradle??

2

I’m not sure exactly what you are describing but in any case I believe the answer is, yes. There are a couple different things possible here:

  1. By default Gradle build incrementally, meaning, it only does work it hasn’t already done. That is, if you build an entire multi-project, change one project, and build again, only the project that changed (and any other projects that depend on it) will recompile.
  2. Within a project, if you only want to recompile the classes that have changed, you can enable incremental compilation. In most cases, unless your project has a very large number of source files, just sticking to #1 will be sufficient.
3

Thnks for the reply.

I was looking for what you explained in point # 1.

Can you explain in brief about this??/ any links would be helpful?

I read about Task{} module in build.gradle file through which we can compile the required project manually.

If I just execute “gradle build”, will it work as you have explained???

Modified a java file in one sub-project and built it using above command, got info like :

:compileJava UP-TO-DATE
:processResources UP-TO-DATE
:classes UP-TO-DATE
:jar UP-TO-DATE
:assemble UP-TO-DATE
:compileTestJava UP-TO-DATE
:processTestResources UP-TO-DATE
:testClasses UP-TO-DATE
:test UP-TO-DATE
:check UP-TO-DATE
:build UP-TO-DATE

It did not consider the change.

Please help me out on this.

4

Please can any one help me out on this???

5

The sub project you modified is not part of the Gradle Project that delegates to the build.gradle file called when you execute ‘gradle build’.

To help you further, you need to show us

  • your project’s structural hierarchy
  • how you defined your sub projects (settings.gradle …)
  • where you were when executing ‘gradle build’

If all is properly configured, yes, executing ‘gradle build’ will work as Mark explained.

6

As Mark has said above in reply to my post -( “By default Gradle build incrementally, meaning, it only does work it hasn’t already done. That is, if you build an entire multi-project, change one project, and build again, only the project that changed (and any other projects that depend on it) will recompile.”).

Can you please let me know if this is achievable??? If so, please give me link to read the same.

Could not find this explanation anywhere in the documentation !!!

7

That’s what I’m trying to explain.

Thanks to task Inputs and Outputs declaration, Gradle knows when a task must be executed again. It prints UP-TO-DATE in the execution log when this task does not need to be executed again.
This happens automatically, you do not need to specify anything, especially when using tasks shipped with Gradle.
(read section 14.9 in here)

Now, you showed us an example where you modified a source file, and yet the task stayed UP-TO-DATE.
This is not possible. There’s no way there is a bug here. There must be a problem with your multi-project settings and/or the gradle build file that is executed by your ‘gradle build’ command.

8

Thanks Francois for the reply…

I got the problem today but unable to solve it.

On using the gradle init command, it generated the gradle files like settings.gradle, build.gradle etc…
However if I compile the project using ‘gradle compile’ or ‘gradle build’ I am unable to get the “.class files” in the build directory.

Can you let me know the reason???

9

Could be a lot of things.
It’s probably better if you start a new thread and show us your build file and project structure (where are your source files)

10

Hey I got the solution…
As my current project directory is different from the gradle expected path, I was getting that error.
Resolved it.

Thanks for help.