How to debug "java.lang.NullPointerException: getService(T::class.java)" in official Kotlin template of IntelliJ IDEA plugin?

Sorry for delay. You can remove all unneeded sample code from the template of course, see https://github.com/JetBrains/intellij-platform-plugin-template/#sample-code

Please check that "Gradle JVM" setting in Preferences | Build, Execution, Deployment | Build Tools | Gradle points to Java **11** installation.

Also update Gradle IntelliJ Plugin version to latest (1.9.0) in IDEsPlugins/IntelliJ_IDEA/build.gradle.kts line 12.

PS: Please make sure to post plugin development questions to " IntelliJ IDEA Open API and Plugin Development" forum, Thanks.

Yann Cebron

Thank you for the answer. 

I checked the Preferences | Build, Execution, Deployment | Build Tools | Gradle. The Gradle JVM is pointing to Project SDK 11.

The Project SDK is currently 11 java version 11.0.3. I'll also show which other versions are available.

About plugin version: I always keep the plugins up-date and currently the Gradle plugin has build version 222.4167.29.

Please check your plugin's module in Project Settings->Modules has also proper Java 11 and language level set.

Also please keep Gradle version itself always up-to-date (7.5.1 currently), change in gradle/wrapper/gradle-wrapper.properties#L3

Yann Cebron

Report about my actions in details. I apologize in advance about long post, but please understand that I am trying to cooperate as possible.

First, I am sorry about I have missed 

update Gradle IntelliJ Plugin version to latest (1.9.0) in IDEsPlugins/IntelliJ_IDEA/build.gradle.kts 

step. I have finished this step now, and now my build.gradle.kts is:

import org.jetbrains.changelog.markdownToHTML
import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

fun properties(key: String) = project.findProperty(key).toString()

plugins {
    // Java support
    id("java")
    // Kotlin support
    id("org.jetbrains.kotlin.jvm") version "1.7.10"
    // Gradle IntelliJ Plugin
    id("org.jetbrains.intellij") version "1.9.0"
    // Gradle Changelog Plugin
    id("org.jetbrains.changelog") version "1.3.0"
    // Gradle Qodana Plugin
    id("org.jetbrains.qodana") version "0.1.12"
}

group = properties("pluginGroup")
version = properties("pluginVersion")

// Configure project's dependencies
repositories {
    mavenCentral()
}

// Configure Gradle IntelliJ Plugin - read more: https://github.com/JetBrains/gradle-intellij-plugin
intellij {
    pluginName.set(properties("pluginName"))
    version.set(properties("platformVersion"))
    type.set(properties("platformType"))
    downloadSources.set(properties("platformDownloadSources").toBoolean())
    updateSinceUntilBuild.set(true)

    // Plugin Dependencies. Uses `platformPlugins` property from the gradle.properties file.
    plugins.set(properties("platformPlugins").split(',').map(String::trim).filter(String::isNotEmpty))
}

// Configure Gradle Changelog Plugin - read more: https://github.com/JetBrains/gradle-changelog-plugin
changelog {
    version.set(properties("pluginVersion"))
    groups.set(emptyList())
}

// Configure Gradle Qodana Plugin - read more: https://github.com/JetBrains/gradle-qodana-plugin
qodana {
    cachePath.set(projectDir.resolve(".qodana").canonicalPath)
    reportPath.set(projectDir.resolve("build/reports/inspections").canonicalPath)
    saveReport.set(true)
    showReport.set(System.getenv("QODANA_SHOW_REPORT").toBoolean())
}

tasks {
    // Set the JVM compatibility versions
    properties("javaVersion").let {
        withType<JavaCompile> {
            sourceCompatibility = it
            targetCompatibility = it
        }
        withType<KotlinCompile> {
            kotlinOptions.jvmTarget = it
        }
    }

    wrapper {
        gradleVersion = properties("gradleVersion")
    }

    patchPluginXml {
        version.set(properties("pluginVersion"))
        sinceBuild.set(properties("pluginSinceBuild"))
        untilBuild.set(properties("pluginUntilBuild"))

        // Extract the <!-- Plugin description --> section from README.md and provide for the plugin's manifest
        pluginDescription.set(
            projectDir.resolve("README.md").readText().lines().run {
                val start = "<!-- Plugin description -->"
                val end = "<!-- Plugin description end -->"

                if (!containsAll(listOf(start, end))) {
                    throw GradleException("Plugin description section not found in README.md:\n$start ... $end")
                }
                subList(indexOf(start) + 1, indexOf(end))
            }.joinToString("\n").run { markdownToHTML(this) }
        )

        // Get the latest available change notes from the changelog file
        changeNotes.set(provider {
            changelog.run {
                getOrNull(properties("pluginVersion")) ?: getLatest()
            }.toHTML()
        })
    }

    runPluginVerifier {
        ideVersions.set(properties("pluginVerifierIdeVersions").split(',').map(String::trim).filter(String::isNotEmpty))
    }

    // Configure UI tests plugin
    // Read more: https://github.com/JetBrains/intellij-ui-test-robot
    runIdeForUiTests {
        systemProperty("robot-server.port", "8082")
        systemProperty("ide.mac.message.dialogs.as.sheets", "false")
        systemProperty("jb.privacy.policy.text", "<!--999.999-->")
        systemProperty("jb.consents.confirmation.enabled", "false")
    }

    signPlugin {
        certificateChain.set(System.getenv("CERTIFICATE_CHAIN"))
        privateKey.set(System.getenv("PRIVATE_KEY"))
        password.set(System.getenv("PRIVATE_KEY_PASSWORD"))
    }

    publishPlugin {
        dependsOn("patchChangelog")
        token.set(System.getenv("PUBLISH_TOKEN"))
        // pluginVersion is based on the SemVer (https://semver.org) and supports pre-release labels, like 2.1.7-alpha.3
        // Specify pre-release label to publish the plugin in a custom Release Channel automatically. Read more:
        // https://plugins.jetbrains.com/docs/intellij/deployment.html#specifying-a-release-channel
        channels.set(listOf(properties("pluginVersion").split('-').getOrElse(1) { "default" }.split('.').first()))
    }
}

Unfortunately, I still have a lot of errors messages:

The Run IDE for UI Tests task is being executed now, but only until try to open some project:

Following your instructions, I have checked the Project Settings->Modules. The Language level is 11:

Finally, I have update the the line 3 in gradle/wrapper/gradle-wrapper.properties. Now it is:

distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
distributionUrl=https\://services.gradle.org/distributions/gradle-7.5.1-bin.zip
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists

Nothing changes even after the background tasks has finished.

In this Youtrack issue, the removing of .idea and .gradle directories has been advised. I have done this, and above errors has been disappeared, however the main error - java.lang.NullPointerException: getService(T::class.java) is still occurs if to run Run IDE for UI Tests.

When I reopened the project after deleting of .idea and .gradle, the Project settings has been updated to:

and Modules settings has been updated to:

The newest output:

2022-10-11 12:40:48,687 [   2800]   WARN - #c.i.n.i.NotificationGroupManagerImpl - Notification group CodeWithMe is already registered (group=com.intellij.notification.NotificationGroup@3738a395). Plugin descriptor: PluginDescriptor(name=Code With Me, id=com.jetbrains.codeWithMe, descriptorPath=plugin.xml, path=~\.gradle\caches\modules-2\files-2.1\com.jetbrains.intellij.idea\ideaIC\2022.2\42c296374014a649785bb84aa6d8dc2d18f2ca0e\ideaIC-2022.2\plugins\cwm-plugin, version=222.3345.118, package=null, isBundled=true)
Info  | RdCoroutineScope          | 45:JobScheduler FJ pool 13/15 | RdCoroutineHost overridden 
2022-10-11 12:41:07,199 [  21312] SEVERE - #c.i.o.p.i.ProjectFrameAllocator - java.lang.NullPointerException: getService(T::class.java) must not be null
java.lang.RuntimeException: java.lang.NullPointerException: getService(T::class.java) must not be null
    at com.intellij.openapi.application.impl.LaterInvocator.invokeAndWait(LaterInvocator.java:118)
    at com.intellij.openapi.application.impl.ApplicationImpl.invokeAndWait(ApplicationImpl.java:505)
    at com.intellij.openapi.application.impl.ApplicationImpl.invokeAndWait(ApplicationImpl.java:525)
    at com.intellij.openapi.project.impl.ProjectManagerExImplKt.openProject(ProjectManagerExImpl.kt:618)
    at com.intellij.openapi.project.impl.ProjectManagerExImplKt.access$openProject(ProjectManagerExImpl.kt:1)
    at com.intellij.openapi.project.impl.ProjectManagerExImpl$doOpenAsync$1.invoke(ProjectManagerExImpl.kt:149)
    at com.intellij.openapi.project.impl.ProjectManagerExImpl$doOpenAsync$1.invoke(ProjectManagerExImpl.kt:60)
    at com.intellij.openapi.project.impl.ProjectUiFrameAllocator$run$progressRunner$1.apply(ProjectFrameAllocator.kt:95)
    at com.intellij.openapi.project.impl.ProjectUiFrameAllocator$run$progressRunner$1.apply(ProjectFrameAllocator.kt:71)
    at com.intellij.openapi.progress.impl.ProgressRunner.lambda$submit$3(ProgressRunner.java:252)
    at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$2(CoreProgressManager.java:188)
    at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$executeProcessUnderProgress$12(CoreProgressManager.java:608)
    at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:683)
    at com.intellij.openapi.progress.impl.CoreProgressManager.computeUnderProgress(CoreProgressManager.java:639)
    at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:607)
    at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:60)
    at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:175)
    at com.intellij.openapi.progress.impl.ProgressRunner.lambda$submit$4(ProgressRunner.java:252)
    at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1768)
    at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1760)
    at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:373)
    at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1182)
    at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1655)
    at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1622)
    at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:165)
Caused by: java.lang.NullPointerException: getService(T::class.java) must not be null
    at com.github.tokugawatakeshi.temp.listeners.MyProjectManagerListener.projectOpened(MyProjectManagerListener.kt:15)

Yann Cebron

Thank you for the investigations.

First: why these listeners/services are need to be specified in plugin.xml even for live templates-only plugin?
Currently my plugin includes live templates only, and there is no instructions about
listeners and services in the official guide.

Well, I need to finish with plugin realize.

Following your instructions, I have replaced applicationListeners with projectListeners.

<projectListeners>
  <listener class="com.github.tokugawatakeshi.temp.listeners.MyProjectManagerListener"
                    topic="com.intellij.openapi.project.ProjectManagerListener"/>
</projectListeners>

About service, according the documentation, the interface and implementation must be species:

<applicationService
    serviceInterface="mypackage.MyApplicationService"
    serviceImplementation="mypackage.MyApplicationServiceImpl"/>

<projectService
  serviceInterface="mypackage.MyProjectService"
    serviceImplementation="mypackage.MyProjectServiceImpl"/>

Currently, I have no any interfaces and I have not touched the Listeners after retrieved the project template.

internal class MyProjectManagerListener : ProjectManagerListener {

    override fun projectOpened(project: Project) {
        project.service<MyProjectService>()
    }
}


class MyApplicationService {

    init {
        println(MyBundle.message("applicationService"))
    }
}


class MyProjectService(project: Project) {

    init {
        println(MyBundle.message("projectService", project.name))
    }
}
```

How I should fill the serviceInterface attribute?

Currently, my plugin.xml is

<idea-plugin>

    <name>Yamato-Daiwa Frontend</name>
    <vendor url="https://github.com/TokugawaTakeshi" email="tokugawa.takesi@gmail.com">Takeshi Tokugawa</vendor>

    <depends>com.intellij.modules.platform</depends>

    <extensions defaultExtensionNs="com.intellij">

        <defaultLiveTemplates file="liveTemplates/Yamato Daiwa Frontend - Pug.xml"/>
        <defaultLiveTemplates file="liveTemplates/Yamato Daiwa Frontend - Stylus.xml"/>
        <defaultLiveTemplates file="liveTemplates/Yamato Daiwa Frontend - Vue_TypeScript.xml"/>

        <projectService
            serviceInterface="com.github.tokugawatakeshi.temp.services.MyApplicationService"
            serviceImplementation="com.github.tokugawatakeshi.temp.services ???"/>

        <projectService
            serviceInterface="com.github.tokugawatakeshi.temp.services.MyProjectService"
            serviceImplementation="com.github.tokugawatakeshi.temp.services ???"/>

    </extensions>


    <projectListeners>
        <listener class="com.github.tokugawatakeshi.temp.listeners.MyProjectManagerListener"
                  topic="com.intellij.openapi.project.ProjectManagerListener"/>
    </projectListeners>

</idea-plugin>

Yann Cebron

Thank you for the support!

Thanks to your help, I finally have published my plugin!