Gradle, what is a sequence of execution in one task? - gradle

Question

Gradle 2.14
I write my custom task "run"
task run() {
def allVariantList = [];
android.applicationVariants.all { variant ->
allVariantList.add(variant.getName())
println "Current allVariantList = " + allVariantList
}
println "Result allVariantList = " + allVariantList
}
Start my task: gradlew run
Result:
Result allVariantList = []
Current allVariantList = [prod_no_check]
Current allVariantList = [prod_no_check, prod]
Current allVariantList = [prod_no_check, prod, stage]
Current allVariantList = [prod_no_check, prod, stage, dev]
Current allVariantList = [prod_no_check, prod, stage, dev, release]
Current allVariantList = [prod_no_check, prod, stage, dev, release, dev_no_check]
Questions:
Why println "Result allVariantList = " + allVariantList run BEFORE println "Current allVariantList = " + allVariantList
I need to println "Result allVariantList = " + allVariantList execute AFTER
println "Current allVariantList = " + allVariantList. How I can do this?

Answer 1

I think the problem is, that at the time your task is configured (you do all your stuff at configuration time, not execution time, the applicationVariants are not yet configured by the android plugin. applicationVariants.all runs on all variants that are already added and also on all variants that get added in the future as soon as they are added.
So your output would suggest that at configuration time no variants are setup yet, thus your result printing is empty and the others come later when the variants are created.
As you do everythign you do at configuration time, it will also always be done, even if you don't execute your task. If you call gradlew help or anything else, you will get the same output.
So either do all your code in the execution phase (wrapping it in a doLast { } closure), or at least do the result printing in the execution phase. If you need your stuff to be done before the execution phase and independently whether your task is actually run or not, you might wrap at least your result printing in an afterEvaluate { } closure that gets executed after the project is evaluated, but still in the configuration phase.

Answer 2

OK, thank everybody. This is work:
task run() {
description "Install and run app on device/emulator"
def allVariantList = [];
android.applicationVariants.all { variant ->
allVariantList.add(variant.getName())
println "Current allVariantList = " + allVariantList
}
doLast {
println "Result allVariantList = " + allVariantList
}
}
Here is the explanation.
https://docs.gradle.org/current/userguide/build_lifecycle.html
Example 22.1. Single project build