Writing a plugin for computing sha1sum for the class files h Gradle Community #community-support

Writing a plugin for computing sha1sum for the cla...

Sreenivas

02/07/2025, 11:38 AM

Writing a plugin for computing sha1sum for the class files, here i'm taking few input properties.. but i'm facing difficulties while running the program.. though i'm passing properties.. inside task execution, its giving always null.. those properties are not being set..

Sreenivas

02/07/2025, 11:39 AM

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package com.myorg.plugins

import org.gradle.api.DefaultTask
import org.gradle.api.Plugin
import org.gradle.api.Project
import org.gradle.api.provider.ListProperty
import org.gradle.api.provider.Property
import org.gradle.api.tasks.Input
import org.gradle.api.tasks.Optional
import org.gradle.api.tasks.TaskAction

import java.security.MessageDigest

class ChecksumPluginV3 implements Plugin<Project> {
    void apply(Project project) {
        def extension = project.extensions.create("checksumConfig", ChecksumPluginExtension3)
        project.tasks.register("computeFileChecksums", ChecksumTask3)
        /*project.tasks.register("computeFileChecksums", ChecksumTask3) { task ->

            task.inputFiles.set(extension.inputFiles)
            task.hashAlgorithms.set(extension.hashAlgorithms)
            task.outputDir.set(extension.outputDir)
            task.outputFormat.set(extension.outputFormat)
        }*/


     
    }
}


abstract class ChecksumTask3 extends DefaultTask {

    @Input
    @Optional
    List<String> inputFiles

    @Input
    @Optional
    List<String> hashAlgorithms

    @Input
    @Optional
    String outputDir

    @Input
    @Optional
    String outputFormat

    @TaskAction
    void computeChecksums() {
        def projectDir = getProject().projectDir

        println("inputFiles: ${inputFiles}")
        println("outputDir: ${outputDir}")
        println("hashAlgorithms: ${hashAlgorithms}")
        println("outputFormat: ${outputFormat}")


        
    }

}

abstract class ChecksumPluginExtension3 {
    abstract List<String> inputFiles
    abstract List<String> hashAlgorithms
    abstract String outputDir
    abstract String outputFormat
}

Sreenivas

02/07/2025, 11:40 AM

I'm always getting null inside task:

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inputFiles: null
outputDir: null
hashAlgorithms: null
outputFormat: null

Sreenivas

02/07/2025, 11:41 AM

I'm under assumption that if extension and task variables have same names, those will be automatically mapped by gradle.. correct me if i'm wrong

Sreenivas

02/07/2025, 11:42 AM

I'm running test case like this:

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// Configure the extension
project.getExtensions().configure(ChecksumPluginExtension3.class, extension -> {
    extension.setInputFiles(Collections.singletonList("src/test/resources/testfile.txt"));
    extension.setHashAlgorithms(Collections.singletonList("SHA-1"));
    extension.setOutputDir("build/checksums");
    extension.setOutputFormat("text");
});

// Execute the task
task.getActions().forEach(action -> action.execute(task));

Sreenivas

02/07/2025, 11:51 AM

If i enable this:

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project.tasks.register("computeFileChecksums", ChecksumTask3) { task ->

            task.inputFiles.set(extension.inputFiles)
            task.hashAlgorithms.set(extension.hashAlgorithms)
            task.outputDir.set(extension.outputDir)
            task.outputFormat.set(extension.outputFormat)
        }

I'm getting NPE at

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task.inputFiles.set(extension.inputFiles)

Trace:

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Caused by: java.lang.NullPointerException: Cannot invoke method set() on null object
	at org.codehaus.groovy.runtime.NullObject.invokeMethod(NullObject.java:91)
	at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:44)

Sreenivas

02/07/2025, 11:53 AM

I tried changing like this too:

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project.tasks.register("computeFileChecksums", ChecksumTask3) { task ->
            task.inputFiles = extension.inputFiles
            task.hashAlgorithms = extension.hashAlgorithms
            task.outputDir = extension.outputDir
            task.outputFormat = extension.outputFormat
        }

but still getting like this:

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inputFiles: null
outputDir: null
hashAlgorithms: null
outputFormat: null

Niels Doucet

02/07/2025, 12:31 PM

You should use lazy properties in both your extension and task implementations and wire those together. https://docs.gradle.org/current/userguide/lazy_configuration.html#lazy_properties

👆 2

Vampire

02/07/2025, 1:42 PM

Besides that, no, there is no auto-name-based mapping in any way. That also would not make much sense, how would Gradle know which extension should match which task. And you should also fix up your types. Neither

String

nor

@Input

is appropriate for input files or output directory. Former should probably be a `ConfigurableFileCollection`with

@InputFiles

and latter a

DirectoryProperty

with

@OutputDirectory

👍 1

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