[#GRADLE-2187] Error : compileJava -> java.lang.NullPointerException (no error message)

[GRADLE-2187] Error : compileJava -> java.lang.NullPointerException (no error message) Created: 20/Mar/12 Updated: 04/Jan/13 Resolved: 23/Apr/12
Status:	Resolved
Project:	Gradle
Affects Version/s:	1.0-milestone-9
Fix Version/s:	1.0-rc-1

Type:

Bug

Reporter:

Gradle Forums

Assignee:

Unassigned

Resolution:

Fixed

Votes:

Description

Hello, I just installed Gradle and I'm trying to understand it but I encounter a problem when trying to build a project with the plugin 'java'.

Just to rule out somes things, I was able to :

1- Install Gradle and run the following script

task hello {
doLast

{ println 'Hello world!' }

}

2- I could compile my Java class using javac and run it using java in the command prompt. Here is the file

public class Hello {

public String execute()

{ return "Hello world!"; }

public static void main(String [] args)

{ Hello hello = new Hello(); System.out.println(hello.execute()); }

}

3- The file is located in the source folder : src/main/java
4- My build.gradle file look like that :
apply plugin: 'java'

5- I use windows 7 (if it's important)

6- If I run the command, gradle build on a folder that doesn't exist (for example src/main/java doesn't exist), everything work. Here is the result :

C:\Users\Denis\Documents\Temp>gradle build
:compileJava UP-TO-DATE
:processResources UP-TO-DATE
:classes UP-TO-DATE
:jar
:assemble
:compileTestJava UP-TO-DATE
:processTestResources UP-TO-DATE
:testClasses UP-TO-DATE
:test
:check
:build

BUILD SUCCESSFUL

7- I have no idea what to do now. Help appreciated

So now here is what I get when I run the command gradle build --stacktrace on an existing folder. In this case the folder where my Hello.java file is located. (src/main/java)

C:\Users\Denis\Documents\Temp>gradle build --stacktrace
:compileJava

FAILURE: Build failed with an exception.

What went wrong:
Execution failed for task ':compileJava'.
> java.lang.NullPointerException (no error message)

Try:
Run with --info or --debug option to get more log output.

Exception is:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':compile
Java'.
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.ex
ecuteActions(ExecuteActionsTaskExecuter.java:68)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.ex
ecute(ExecuteActionsTaskExecuter.java:46)
at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExec
uter.execute(PostExecutionAnalysisTaskExecuter.java:34)
at org.gradle.api.internal.changedetection.CacheLockHandlingTaskExecuter
$1.run(CacheLockHandlingTaskExecuter.java:34)
at org.gradle.cache.internal.DefaultCacheAccess$2.create(DefaultCacheAcc
ess.java:200)
at org.gradle.cache.internal.DefaultCacheAccess.longRunningOperation(Def
aultCacheAccess.java:172)
at org.gradle.cache.internal.DefaultCacheAccess.longRunningOperation(Def
aultCacheAccess.java:198)
at org.gradle.cache.internal.DefaultPersistentDirectoryStore.longRunning
Operation(DefaultPersistentDirectoryStore.java:111)
at org.gradle.api.internal.changedetection.DefaultTaskArtifactStateCache
Access.longRunningOperation(DefaultTaskArtifactStateCacheAccess.java:83)
at org.gradle.api.internal.changedetection.CacheLockHandlingTaskExecuter
.execute(CacheLockHandlingTaskExecuter.java:32)
at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.exec
ute(SkipUpToDateTaskExecuter.java:55)
at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execut
e(ValidatingTaskExecuter.java:57)
at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecu
ter.execute(SkipEmptySourceFilesTaskExecuter.java:41)
at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter
.execute(SkipTaskWithNoActionsExecuter.java:51)
at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execut
e(SkipOnlyIfTaskExecuter.java:52)
at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter
.execute(ExecuteAtMostOnceTaskExecuter.java:42)
at org.gradle.api.internal.AbstractTask.executeWithoutThrowingTaskFailur
e(AbstractTask.java:247)
at org.gradle.execution.DefaultTaskGraphExecuter.executeTask(DefaultTask
GraphExecuter.java:192)
at org.gradle.execution.DefaultTaskGraphExecuter.doExecute(DefaultTaskGr
aphExecuter.java:177)
at org.gradle.execution.DefaultTaskGraphExecuter.execute(DefaultTaskGrap
hExecuter.java:83)
at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTask
ExecutionAction.java:36)
at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecute
r.java:61)
at org.gradle.execution.DefaultBuildExecuter.access$200(DefaultBuildExec
uter.java:23)
at org.gradle.execution.DefaultBuildExecuter$2.proceed(DefaultBuildExecu
ter.java:67)
at org.gradle.api.internal.changedetection.TaskCacheLockHandlingBuildExe
cuter$1.run(TaskCacheLockHandlingBuildExecuter.java:31)
at org.gradle.cache.internal.DefaultCacheAccess$1.create(DefaultCacheAcc
ess.java:111)
at org.gradle.cache.internal.DefaultCacheAccess.useCache(DefaultCacheAcc
ess.java:126)
at org.gradle.cache.internal.DefaultCacheAccess.useCache(DefaultCacheAcc
ess.java:109)
at org.gradle.cache.internal.DefaultPersistentDirectoryStore.useCache(De
faultPersistentDirectoryStore.java:103)
at org.gradle.api.internal.changedetection.DefaultTaskArtifactStateCache
Access.useCache(DefaultTaskArtifactStateCacheAccess.java:79)
at org.gradle.api.internal.changedetection.TaskCacheLockHandlingBuildExe
cuter.execute(TaskCacheLockHandlingBuildExecuter.java:29)
at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecute
r.java:61)
at org.gradle.execution.DefaultBuildExecuter.access$200(DefaultBuildExec
uter.java:23)
at org.gradle.execution.DefaultBuildExecuter$2.proceed(DefaultBuildExecu
ter.java:67)
at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildEx
ecutionAction.java:32)
at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecute
r.java:61)
at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecute
r.java:54)
at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(Default
GradleLauncher.java:155)
at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradle
Launcher.java:110)
at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLaun
cher.java:78)
at org.gradle.launcher.cli.RunBuildAction.execute(RunBuildAction.java:42
)
at org.gradle.launcher.cli.RunBuildAction.execute(RunBuildAction.java:28
)
at org.gradle.launcher.exec.ExceptionReportingAction.execute(ExceptionRe
portingAction.java:32)
at org.gradle.launcher.exec.ExceptionReportingAction.execute(ExceptionRe
portingAction.java:21)
at org.gradle.launcher.cli.CommandLineActionFactory$WithLoggingAction.ex
ecute(CommandLineActionFactory.java:302)
at org.gradle.launcher.cli.CommandLineActionFactory$WithLoggingAction.ex
ecute(CommandLineActionFactory.java:286)
at org.gradle.launcher.Main.doAction(Main.java:48)
at org.gradle.launcher.exec.EntryPoint$1.execute(EntryPoint.java:53)
at org.gradle.launcher.exec.EntryPoint$1.execute(EntryPoint.java:51)
at org.gradle.launcher.exec.Execution.execute(Execution.java:28)
at org.gradle.launcher.exec.EntryPoint.run(EntryPoint.java:39)
at org.gradle.launcher.Main.main(Main.java:39)
at org.gradle.launcher.ProcessBootstrap.runNoExit(ProcessBootstrap.java:
51)
at org.gradle.launcher.ProcessBootstrap.run(ProcessBootstrap.java:33)
at org.gradle.launcher.GradleMain.main(GradleMain.java:24)
Caused by: java.lang.NullPointerException
at org.gradle.api.internal.tasks.compile.jdk6.Jdk6JavaCompiler.createCom
pileTask(Jdk6JavaCompiler.java:52)
at org.gradle.api.internal.tasks.compile.jdk6.Jdk6JavaCompiler.execute(J
dk6JavaCompiler.java:39)
at org.gradle.api.internal.tasks.compile.jdk6.Jdk6JavaCompiler.execute(J
dk6JavaCompiler.java:33)
at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.delegat
eAndHandleErrors(NormalizingJavaCompiler.java:95)
at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.execute
(NormalizingJavaCompiler.java:48)
at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.execute
(NormalizingJavaCompiler.java:34)
at org.gradle.api.internal.tasks.compile.DelegatingJavaCompiler.execute(
DelegatingJavaCompiler.java:29)
at org.gradle.api.internal.tasks.compile.DelegatingJavaCompiler.execute(
DelegatingJavaCompiler.java:20)
at org.gradle.api.internal.tasks.compile.IncrementalJavaCompilerSupport.
execute(IncrementalJavaCompilerSupport.java:33)
at org.gradle.api.internal.tasks.compile.IncrementalJavaCompilerSupport.
execute(IncrementalJavaCompilerSupport.java:23)
at org.gradle.api.tasks.compile.Compile.compile(Compile.java:60)
at org.gradle.api.internal.BeanDynamicObject$MetaClassAdapter.invokeMeth
od(BeanDynamicObject.java:196)
at org.gradle.api.internal.BeanDynamicObject.invokeMethod(BeanDynamicObj
ect.java:102)
at org.gradle.api.internal.CompositeDynamicObject.invokeMethod(Composite
DynamicObject.java:99)
at org.gradle.api.tasks.compile.Compile_Decorated.invokeMethod(Unknown S
ource)
at org.gradle.util.ReflectionUtil.invoke(ReflectionUtil.groovy:23)
at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskF
actory$4.execute(AnnotationProcessingTaskFactory.java:150)
at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskF
actory$4.execute(AnnotationProcessingTaskFactory.java:145)
at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(Abstra
ctTask.java:477)
at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(Abstra
ctTask.java:466)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.ex
ecuteActions(ExecuteActionsTaskExecuter.java:60)
... 54 more

BUILD FAILED

Total time: 2.948 secs

Thx for help!

Comments

Comment by Gradle Forums [ 20/Mar/12 ]

Not sure if I understand you correctly. You have one source file in src/main/java and as soon as you run "gradle build" from the root project you get the Nullpointer exception? Unfortunately I cannot yet reproduce your bug.

regards,
René

Comment by Gradle Forums [ 20/Mar/12 ]

Can you post the output of `gradle -v`, please? Also, what is your JAVA_HOME environment variable set to, if anything?

Comment by Gradle Forums [ 20/Mar/12 ]

Thx for reply.

Here is the output of gradle -v

C:\Users\Denis\Documents\Temp>gradle -v

------------------------------------------------------------
Gradle 1.0-milestone-9
------------------------------------------------------------

Gradle build time: mardi 13 mars 2012 16 h 10 UTC
Groovy: 1.8.6
Ant: Apache Ant(TM) version 1.8.2 compiled on December 20 2010
Ivy: 2.2.0
JVM: 1.6.0_23 (Sun Microsystems Inc. 19.0-b09)
OS: Windows 7 6.1 amd64

C:\Users\Denis\Documents\Temp>

I didn't had a variable JAVA_HOME but the path for the JDK was in my PATH variable.

I tried creating a variable JAVA_HOME with the path to the JDK but it didn't seems to change anything, still get the same error.

Comment by Gradle Forums [ 20/Mar/12 ]

@Rene Yes, I'm in a folder containaing the folder src/main/java/Hello.java. When I run the command "gradle build" it give me the NullPointerException.

I tried changing the sourceSet like it was explain in the documentation and it crash too. In fact as soon as I referenced an existing folder it crash but if I referenced a folder that doesn't exist it print that the build is a success with the usual message :

BUILD SUCCESSFUL

Comment by Gradle Forums [ 20/Mar/12 ]

I was able to reproduce this error by:
1. point the JAVA_HOME to a JRE installation instead of a JDK
2. remove the JAVA_HOME variable at all.

Can you please double check that your JAVA_HOME variable points to a valid JDK installation (by calling "set JAVA_HOME" directly before running the gradle command)? Nevertheless, Gradle should be more gracefully here and not fail with a NullpointerException.

regards,
René

Comment by Gradle Forums [ 20/Mar/12 ]

Thx for the help!!

It work. This morning when I restart my comp it gave me an error about an invalid JAVA_HOME variable instead of the NullPointerException.

Then instead of putting the bin folder of the JDK as my path I just put the path to the JDK and now it works

Any way to mark this issue as fixed?

Generated at Wed Jun 30 12:15:05 CDT 2021 using Jira 8.4.2#804003-sha1:d21414fc212e3af190e92c2d2ac41299b89402cf.

[GRADLE-2187] Error : compileJava -> java.lang.NullPointerException (no error message) Created: 20/Mar/12 Updated: 04/Jan/13 Resolved: 23/Apr/12