Gradle - Building Java Web Applications

Question

I try to do this tutorial since several days. I have installed Jetty and launch with java -jar start.jar.

But there is a problem and I can't run on http://localhost:8080/webdemo.

On Gradle https://guides.gradle.org/building-java-web-applications/?_ga=2.70016208.115474122.1530432194-1213495054.1529791313

When we do this command bash gradlew appRun, that's the result:

$ ./gradlew appRun
:prepareInplaceWebAppFolder
:createInplaceWebAppFolder UP-TO-DATE
:compileJava
:processResources UP-TO-DATE
:classes
:prepareInplaceWebAppClasses
:prepareInplaceWebApp
:appRun
12:25:13 INFO  Jetty 9.2.15.v20160210 started and listening on port 8080
12:25:13 INFO  webdemo runs at:
12:25:13 INFO    http://localhost:8080/webdemo
Press any key to stop the server.
> Building 87% > :appRun

But this is my result:

Starting a Gradle Daemon, 1 busy Daemon could not be reused, use --status for details
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.codehaus.groovy.reflection.CachedClass (file:/home/koala/.gradle/caches/modules-2/files-2.1/org.codehaus.groovy/groovy/2.4.11/52a60df8b4cbfe39469171a42ca77a3e4eb4e737/groovy-2.4.11.jar) to method java.lang.Object.finalize()
WARNING: Please consider reporting this to the maintainers of org.codehaus.groovy.reflection.CachedClass
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
Exception in thread "main" java.lang.NullPointerException: Cannot invoke method getText() on null object
        at org.codehaus.groovy.runtime.NullObject.invokeMethod(NullObject.java:91)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:48)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
        at org.codehaus.groovy.runtime.callsite.NullCallSite.call(NullCallSite.java:35)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)
        at org.akhikhl.gretty.Runner.initLogback(Runner.groovy:65)
        at org.akhikhl.gretty.Runner$initLogback.callStatic(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallStatic(CallSiteArray.java:56)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callStatic(AbstractCallSite.java:194)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callStatic(AbstractCallSite.java:206)
        at org.akhikhl.gretty.Runner.run(Runner.groovy:115)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:564)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoCachedMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:210)
        at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.call(PogoMetaMethodSite.java:71)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:117)
        at org.akhikhl.gretty.Runner.main(Runner.groovy:44)
Exception in thread "Thread-23" org.gradle.process.internal.ExecException: Process 'command '/usr/lib/jvm/java-10-oracle/bin/java'' finished with non-zero exit value 1
        at org.gradle.process.internal.DefaultExecHandle$ExecResultImpl.assertNormalExitValue(DefaultExecHandle.java:395)
        at org.gradle.process.internal.DefaultJavaExecAction.execute(DefaultJavaExecAction.java:37)
        at org.gradle.api.internal.file.DefaultFileOperations.javaexec(DefaultFileOperations.java:192)
        at org.gradle.api.internal.project.DefaultProject.javaexec(DefaultProject.java:1087)
        at org.gradle.api.internal.project.DefaultProject.javaexec(DefaultProject.java:1082)
        at org.gradle.api.Project$javaexec$6.call(Unknown Source)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)
        at org.akhikhl.gretty.DefaultLauncher.javaExec(DefaultLauncher.groovy:89)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:564)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)
        at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:384)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1022)
        at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.callCurrent(PogoMetaClassSite.java:69)
        at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:52)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:154)
        at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:166)
        at org.akhikhl.gretty.LauncherBase$_launchThread_closure4.doCall(LauncherBase.groovy:256)
        at org.akhikhl.gretty.LauncherBase$_launchThread_closure4.doCall(LauncherBase.groovy)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:564)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)
        at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:294)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1022)
        at groovy.lang.Closure.call(Closure.java:414)
        at groovy.lang.Closure.call(Closure.java:408)
        at groovy.lang.Closure.run(Closure.java:495)
        at java.base/java.lang.Thread.run(Thread.java:844)
<===========--> 87% EXECUTING [10m 47s]
> :appRun
> IDLE

Many thanks for unblock my problem

Answer 1

The guide is out of date, sorry. Replace the block:

plugins {
    id 'war'
    id 'org.akhikhl.gretty' version '1.4.2' 
}

with

plugins {
    id 'war'
    id 'org.gretty' version '2.2.0' 
}

I'll schedule the guide for an update.

The warning is not critical and is the result of changes to the JVM between major versions. You can learn more about it in the Gradle issue tracker.