gradle "No main class specified" even though main class exists

Question

I try to run this gradle task:

task resources_cleaner_bl(type: JavaExec) {
    classpath sourceSets.main.runtimeClasspath
    systemProperties['cleanTarget'] = 'bl'
    mainClassName = "com.w.routing.automation.runners.cleaner.ResourcesCleanerRunner"
}

with this Java code:

package com.w.routing.automation.runners.cleaner;

public class ResourcesCleanerRunner {


    private static IResourcesCleaner resourcesCleaner;
    private static Injector injector;


    public static void main(String args[]) {
        init();
        String cleanTarget = System.getProperty("cleanTarget");
        switch (cleanTarget) {

but i get this error:

15:48:06.532 [ERROR] [org.gradle.BuildExceptionReporter] FAILURE: Build failed with an exception.
15:48:06.533 [ERROR] [org.gradle.BuildExceptionReporter] 
15:48:06.549 [ERROR] [org.gradle.BuildExceptionReporter] * What went wrong:
15:48:06.549 [ERROR] [org.gradle.BuildExceptionReporter] Execution failed for task ':resources_cleaner_bl'.
15:48:06.549 [ERROR] [org.gradle.BuildExceptionReporter] > No main class specified
15:48:06.550 [ERROR] [org.gradle.BuildExceptionReporter] 
15:48:06.550 [ERROR] [org.gradle.BuildExceptionReporter] * Exception is:
15:48:06.550 [ERROR] [org.gradle.BuildExceptionReporter] org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':resources_cleaner_bl'.
15:48:06.550 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:69)
15:48:06.550 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:46)
15:48:06.551 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExecuter.execute(PostExecutionAnalysisTaskExecuter.java:35)
15:48:06.551 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:64)
15:48:06.551 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:58)
15:48:06.552 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:52)
15:48:06.552 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:52)
15:48:06.553 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:53)
15:48:06.553 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:43)
15:48:06.553 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:203)
15:48:06.577 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:185)
15:48:06.577 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.processTask(AbstractTaskPlanExecutor.java:66)
15:48:06.578 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.taskgraph.AbstractTaskPlanExecutor$TaskExecutorWorker.run(AbstractTaskPlanExecutor.java:50)
15:48:06.578 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor.process(DefaultTaskPlanExecutor.java:25)
15:48:06.578 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter.execute(DefaultTaskGraphExecuter.java:110)
15:48:06.578 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTaskExecutionAction.java:37)
15:48:06.578 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:37)
15:48:06.578 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.DefaultBuildExecuter.access$000(DefaultBuildExecuter.java:23)
15:48:06.578 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.DefaultBuildExecuter$1.proceed(DefaultBuildExecuter.java:43)
15:48:06.578 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildExecutionAction.java:32)
15:48:06.579 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:37)
15:48:06.579 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:30)
15:48:06.579 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.initialization.DefaultGradleLauncher$4.run(DefaultGradleLauncher.java:154)
15:48:06.579 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.internal.Factories$1.create(Factories.java:22)
15:48:06.579 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:90)
15:48:06.579 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:52)
15:48:06.579 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:151)
15:48:06.580 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.initialization.DefaultGradleLauncher.access$200(DefaultGradleLauncher.java:32)
15:48:06.580 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.initialization.DefaultGradleLauncher$1.create(DefaultGradleLauncher.java:99)
15:48:06.580 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.initialization.DefaultGradleLauncher$1.create(DefaultGradleLauncher.java:93)
15:48:06.580 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:90)
15:48:06.580 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:62)
15:48:06.580 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:93)
15:48:06.580 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:82)
15:48:06.580 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.exec.InProcessBuildActionExecuter$DefaultBuildController.run(InProcessBuildActionExecuter.java:94)
15:48:06.581 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.tooling.internal.provider.ExecuteBuildActionRunner.run(ExecuteBuildActionRunner.java:28)
15:48:06.581 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35)
15:48:06.581 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:43)
15:48:06.581 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:28)
15:48:06.581 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.exec.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:75)
15:48:06.581 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.exec.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:45)
15:48:06.581 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.exec.DaemonUsageSuggestingBuildActionExecuter.execute(DaemonUsageSuggestingBuildActionExecuter.java:51)
15:48:06.582 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.exec.DaemonUsageSuggestingBuildActionExecuter.execute(DaemonUsageSuggestingBuildActionExecuter.java:28)
15:48:06.582 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.launcher.cli.RunBuildAction.run(RunBuildAction.java:43)
15:48:06.582 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.internal.Actions$RunnableActionAdapter.execute(Actions.java:170)
15:48:06.584 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:127)
15:48:06.584 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:56)
15:48:06.584 [ERROR] [org.gradle.BuildExceptionReporter] Caused by: java.lang.IllegalStateException: No main class specified
15:48:06.584 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.process.internal.JavaExecHandleBuilder.build(JavaExecHandleBuilder.java:212)
15:48:06.585 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.process.internal.DefaultJavaExecAction.execute(DefaultJavaExecAction.java:28)
15:48:06.585 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.api.tasks.JavaExec.exec(JavaExec.java:74)
15:48:06.585 [ERROR] [org.gradle.BuildExceptionReporter]        at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:75)

what am i missing as i have the main class with the right namespace?

Answer 1

You need to use the main property on the JavaExec task. The mainClassName property does not exist.

task resources_cleaner_bl(type: JavaExec) {
    classpath sourceSets.main.runtimeClasspath
    systemProperties['cleanTarget'] = 'bl'
    main = "com.w.routing.automation.runners.cleaner.ResourcesCleanerRunner"
}

https://docs.gradle.org/current/dsl/org.gradle.api.tasks.JavaExec.html