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gradle javaexec error "'apiElements' directly is not allowed"- Gradle 5.4.1

I am new to Gradle and trying to migrate an existing system build from ant to Gradle.
As part of this I need to run a java program on every file in a directory. Directory contains xml files and the java code will parse and convert .xml to .java files (and these Java files would be build to generate class and package in final jar) after performing some business specific transformation.
below is a function I wrote in Gradle
private runJavaFile(String dirPath) {
FileTree tree = fileTree(dir: dirPath, include: '**/*.xml')
tree.each {
def xmlfile = it.path
def javaFile = it.path.replaceFirst(".xml", ".java")
javaexec { //// getting error on this line
classpath configurations.all
main = 'XmlToJavaParser'
args = ["$xmlfile", "$javaFile", 'Java']
}
}
}
I am calling this function from a Gradle task by passing the dir path which contains the xml files to be parsed.
While running the task, I am getting below error:
> Resolving configuration 'apiElements' directly is not allowed
Any help would be appreciated.
Let me know if any more information is needed.

In Gradle, a configuration represents a group of artifacts and their dependencies. You typically have several configurations depending on what you want to do. For instance, you could have one where you declare which dependencies are needed for compilation, which are only needed at runtime, or which are needed for running a particular Java application.
In your case, you are saying that the classpath to the XmlToJavaParser class is "all configurations combined" and that doesn't really make sense. You are also not allowed to do that as some configurations from the Java plugin are not resolvable like this, which is why you get an error.
So to fix it, you should declare your own configuration for XmlToJavaParser. You can then declare dependencies for it like you normally do. Example (using the Groovy DSL):
configurations {
xmlJavaParser {
canBeResolved = true
canBeConsumed = false
}
}
dependencies {
xmlJavaParser "org.example:xml-java-parser:1.0" // or whatever you need
}
private runJavaFile(String dirPath) {
// ...
javaexec {
classpath = configurations.xmlJavaParser // The configuration is referenced here
main = 'XmlToJavaParser'
args = ["$xmlfile", "$javaFile", 'Java']
}
}
There are also other ways to go about it. But the main point is to not use configurations.all as a classpath.

How to use BuildConfig.DEBUG as task variable in build.gradle on Android Studio 4.0?

I have a custom task that required to check if the current build is debug or release, and then use the corresponding classpath.
The normal task definition:
task custom_java_task(type: JavaExec) {
classpath "build/intermediates/javac/debug/classes/"
main = "com.testapp.JavaTaskTest"
args "test", "${projectDir}"
}
The task definition needs to check BuildConfig.DEBUG and set the different value for classpath:
task custom_java_task(type: JavaExec) {
classpath BuildConfig.DEBUG ? "build/intermediates/javac/debug/classes/" : "build/intermediates/javac/release/classes/"
main = "com.testapp.JavaTaskTest"
args "test", "${projectDir}"
}
The build will fail with the following error:
Could not get unknown property 'BuildConfig' for task ':app:custom_java_task' of type org.gradle.api.tasks.JavaExec.
Thanks.

BuildConfig is generated set of properties that cannot be used from within gradle scripts. It is actually generated based on your build.gradle
But there are some ways to achieve what you want for example like this:
First in project level build.gradle under buildscript you can define the function / method and name ti however you want (eg. doStuff)
buildscript {
...
ext.doStuff = { buildType ->
// do stuff based on buildType param
}
...
}
Than in your module level build.gradle, simply do
android {
...
buildTypes {
debug {
...
doStuff("debug")
}
release {
...
doStuff("release")
}
}
...
}
Now this is just to give you a hint on the abilities of build.gradle files, you can build further from this.
Cheers

gradle Jigsaw module not found

I try to run a very simple gradle project which uses java 9 modules, but i receive the following error.
/home/vadim/IdeaProjects/test_modules/src/main/java/module-info.java:2: error: module not found: HdrHistogram
requires HdrHistogram;
^
Here is it https://github.com/vad0/test_modules.
The main class does basically nothing.
package app;
import org.HdrHistogram.Histogram;
public class RunHdr {
public static void main(String[] args) {
final Histogram histogram = new Histogram(5);
System.out.println(histogram);
}
}
It uses only one dependency: HdrHistogram. I included this magic command in build.gradle according to official gradle tutorial https://docs.gradle.org/current/samples/sample_java_modules_multi_project.html.
java {
modularity.inferModulePath = true
}
The whole build.gradle looks like this.
plugins {
id 'java'
}
group 'org.example'
version '1.0-SNAPSHOT'
repositories {
mavenCentral()
}
java {
modularity.inferModulePath = true
}
dependencies {
compile group: 'org.hdrhistogram', name: 'HdrHistogram', version: '2.1.12'
testCompile group: 'junit', name: 'junit', version: '4.12'
}
module.info looks like this
module test.modules.main {
requires HdrHistogram;
}
I have already read a number of tutorials on Jigsaw and a whole bunch of stackoverflow questions related to it, but still can't make this simple example work. How do i fix it?
Thank you

Unfortunately, gradle does not treat every jar as a module (in simple words). If you want to find out how exactly is gradle building the module-path (as opposed to class-path), you probably want to start from here, specifically at the isModuleJar method. It's pretty easy to understand (though it took me almost two days to set-up gradle and debug the problem out) that the dependency that you are trying to use : gradle says that it is not a module (it isn't wrong, but I am not sure it is correct either). To make it very correct, gradle will add your dependency to the CLASSPATH, but in the very next line: it will not add your dependency to the module-path, because if fails the filter in isModuleJar.
I do not know if this is a bug or not, or may be this is on purpose, but the solution is easy:
plugins.withType(JavaPlugin).configureEach {
java {
modularity.inferModulePath = true
}
tasks.withType(JavaCompile) {
doFirst {
options.compilerArgs = [
'--module-path', classpath.asPath,
]
classpath = files()
}
}
}
you add it to the path, on purpose. I will flag this as a defect and let's see what they have to say.
EDIT
Even better, use a plugin that is written by a gradle commiter:
plugins {
id 'java'
id 'de.jjohannes.extra-java-module-info' version "0.1"
}
And the easiest option on your case is to do :
extraJavaModuleInfo {
automaticModule("HdrHistogram-2.1.12.jar", "HdrHistogram")
}

Problem when auto generating gRPC stub files using Gradle

I've been asked to implement some gRPC classes for a college course, and have run into some problems when generating the java classes from one source proto file.
Some background first: it's a fairly basic service, with a simple method that receives an id and returns a phone and an email. This is the proto file (BuscarData means FetchData, sorry for the leftover non translation!):
syntax = 'proto3';
option java_multiple_files=true;
option java_generic_services= true;
package uy.edu.um.sd20;
message DataRequest {
int32 id = 1;
}
message DataResponse {
string phone = 1;
string email = 2;
}
service DataRepo {
rpc BuscarData (DataRequest) returns (DataResponse);
}
The idea I had was to generate the classes with gradle plugins. My build.gradle:
plugins {
id 'java'
id "com.google.protobuf" version '0.8.8'
}
apply plugin: 'java'
group 'org.example'
version '1.0-SNAPSHOT'
repositories {
mavenCentral()
}
dependencies {
testCompile group: 'junit', name: 'junit', version: '4.12'
compile group: 'com.google.protobuf', name: 'protobuf-java', version: '3.11.4'
implementation 'io.grpc:grpc-netty-shaded:1.29.0'
implementation 'io.grpc:grpc-protobuf:1.29.0'
implementation 'io.grpc:grpc-stub:1.29.0'
}
sourceSets {
main {
proto {
srcDir 'src/main/proto'
}
java {
srcDirs 'src/main/java', 'generated-sources/main/java'
}
}
}
protobuf {
protoc {
artifact = 'com.google.protobuf:protoc:3.11.0'
}
plugins {
grpc {
artifact = 'io.grpc:protoc-gen-grpc-java:1.29.0'
}
}
generateProtoTasks.generatedFilesBaseDir = 'generated-sources'
generateProtoTasks {
all().each { task ->
// Here you can configure the task
}
ofSourceSet('main')
}
}
From what I understood, everything's there: the grpc and protoc dependencies, and the plugin which enables protoc to compile grpc (protoc-gen-grpc), and where to deposit the generated files.
However, there are two problems:
the generated-sources are not marked as source or anything like that, meaning they cannot be imported from other classes
if I'm not mistaken, the generated-sources should generate a skeleton of DataRepoImpl so that I can add the code needed for BuscarData. However, it didn't. Or maybe I should create it, extending from DataRepo.java, but I couldn't test it, due to problem n°1.
I've added a screenshot of the project file structure:
img
As you can see, quite a lot (if not all) of the gradle settings are copy-pasted and scavenged from many different web-sites. I hope I was careful enough not to repeat any imports. There are similar questions, and I tried the solutions there, but no luck there. One example, with which I knew I had to include the gen grpc plugin: another SO question
Any tip regarding anything else is welcome! I'm new to stackoverflow question-asking, so I may have made mistakes regarding the question specificity or aim of the question.
Thanks!
Franri.

For 1), the plugin should put the generated files are the input for java compile tasks even if you do not explicitly add 'generated-sources/main/java' in the sourceSets configuration. Version 0.8.8 has been a while, you can try with newer versions. There might have been some minor fixes for things you may hit.
For 2), you did not add grpc plugin to each generateProto task. It should be
generateProtoTasks {
all().each { task ->
task.plugins { grpc{} }
}
ofSourceSet('main')
}

How to make Gradle fail the build if a file dependency is not found?

I have a Gradle build that has some dependencies of the form
compile files('path/to/local/lib.jar')
(the build is being migrated - eventually these will be replaced)
The build failed because one of these paths was incorrectly specified. But it failed due to a compile error - it looked like Gradle silently ignored the missing dependency.
Is there a simple option or switch that will force Gradle to fail the build if any dependency (particularly local file dependencies) cannot be resolved (eg., file missing)?
Edit: to clarify further:
If a dependency cannot be found in the configured repositories, Gradle will fail the build when attempting to resolve them, as expected.
BUT - if a dependency is defined as "compile files ....", and the file specified does not exist at build time, Gradle will IGNORE that error, and attempt compilation anyway. That seems spectacularly wrong-headed and inconsistent default behaviour.
My question is - is there a Gradle option or switch or environment variable or system property that I can set to force Gradle to verify that file dependencies exist? (E.g,, behave in a sane and rational way?)

This is a bit of an old thread, but given that none of the currently proposed solutions actually works, and the solution appears to be trivial (collating two of them), I am leaving it here for future reference.
The point here is that we simply want to ensure that the files do exist, so we can just use the exists() method of the File class:
task ensureDepsExist() {
doLast {
configurations.implementation.canBeResolved(true)
Set<File> impFiles = configurations.implementation.resolve()
impFiles.forEach { f ->
if (!f.exists()) {
ant.fail "${f} could not be found"
}
}
}
}
compileJava.dependsOn ensureDepsExist
The canBeResolved() call is required, or Gradle will complain that configurations dependencies cannot be resolved.

Here's how you can check transitive dependencies using Gradle 7.3 (example: Fail if the project depends on log4j directly or transitively).
Kotlin DSL
configurations {
all {
relsolutionStrategy {
eachDependency {
if (requested.name == "log4j") {
throw RuntimeException("Project depends on log4j")
}
}
}
}
}
Groovy DSL
configurations.all {
resolutionStrategy.eachDependency { DependencyResolveDetails details ->
if (details.requested.name == 'log4j') {
throw new RuntimeException("Project depends on log4j")
}
}
}

You could do something as shown below. It is not a built-in Gradle function but does not require code to check each dependency specifically (it checks all in the compile configuration):
apply plugin: 'java'
dependencies {
compile files('lib/abc.jar')
compile files('lib/def.jar')
}
task checkDependencies() {
doLast {
configurations.compile.each { file ->
assert file.exists()
}
}
}
compileJava.dependsOn checkDependencies

To fail the build you can:
ant.fail('message why it failed')
Then you can craft a condition then fail the build with nice message ;)
I would suggest to create a task that will bring the file to the project first with a condition to check if the file is available etc if not then throw a Gradle exception and fail the build with a message, and execute the task first in the execution phase.
I have no chance to test it now but it could be something like this, correct me if any syntax is wrong - but you should get the idea.
def yourDep = $/\path\to\your\depdendency/$
task bringDeps << {
if (yourDep.exists()){
copy {
from yourDep
into $projectDir/depsOrSmthg
}
} else{
ant.fail('message why it failed')
}
}

task ensureDependenciesExist() {
doLast {
configurations.implementation.canBeResolved(true)
DependencySet deps = configurations.implementation.getDependencies()
Set<File> impFiles = configurations.implementation.resolve()
deps.each { d ->
boolean depWasResolved = impFiles.any { impFile -> impFile.name.find(".*${d.name}.*${d.version}") }
if (!depWasResolved) {
println "${d} was not resolved"
assert depWasResolved
}
}
}
}
compileJava.dependsOn ensureDependenciesExist