Type mismatch for java files

[kiril-akshonau]

Hi guys.

I've faced with strange issue in my java class: eclipse can't compile code

    public static void main(String[] args) {
        List<Foo> foos = null;
        Optional.ofNullable(foos)
            .map(list -> list.stream().collect(Collectors.toMap(foo -> foo.getFoo(), foo -> foo)))
            .orElse(Collections.emptyMap());
    }
    private static class Foo {
        private String foo;
        public String getFoo() {
            return foo;
        }
    }

Compilation error: Type mismatch: cannot convert from Optional<Object> to <unknown>

Without groovy plugin everything compiles fine

As workaround I can define type of foo variable explicitly and everything compiles fine

.map(list -> list.stream().collect(Collectors.toMap((Foo foo) -> foo.getFoo(), foo -> foo)))

My system("fresh" eclipse installation from official site and groovy plugin):

eclipse.buildId=4.6.1.M20160907-1200
java.version=1.8.0_111
java.vendor=Oracle Corporation
Windows7 x64

[kiril-akshonau]

I have some errors in error log, but I'm not sure that they was cause of this issue

eclipse.buildId=4.6.1.M20160907-1200
java.version=1.8.0_111
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=en_US
Framework arguments:  -product org.eclipse.epp.package.jee.product -product org.eclipse.epp.package.jee.product -product org.eclipse.epp.package.jee.product
Command-line arguments:  -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.jee.product -product org.eclipse.epp.package.jee.product -data file:/C:/Users/Kiril_Akshonau/workspace/ -product org.eclipse.epp.package.jee.product

org.codehaus.groovy.eclipse.ui
Error
Thu Dec 01 17:08:49 MSK 2016
Error installing JUnit monospace font listener

java.lang.NullPointerException
	at org.codehaus.groovy.eclipse.GroovyPlugin.addMonospaceFontListener(GroovyPlugin.java:141)
	at org.codehaus.groovy.eclipse.GroovyPlugin.start(GroovyPlugin.java:114)
	at org.eclipse.osgi.internal.framework.BundleContextImpl$3.run(BundleContextImpl.java:774)
	at org.eclipse.osgi.internal.framework.BundleContextImpl$3.run(BundleContextImpl.java:1)
	at java.security.AccessController.doPrivileged(Native Method)
	at org.eclipse.osgi.internal.framework.BundleContextImpl.startActivator(BundleContextImpl.java:767)
	at org.eclipse.osgi.internal.framework.BundleContextImpl.start(BundleContextImpl.java:724)
	at org.eclipse.osgi.internal.framework.EquinoxBundle.startWorker0(EquinoxBundle.java:932)
	at org.eclipse.osgi.internal.framework.EquinoxBundle$EquinoxModule.startWorker(EquinoxBundle.java:309)
	at org.eclipse.osgi.container.Module.doStart(Module.java:581)
	at org.eclipse.osgi.container.Module.start(Module.java:449)
	at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:470)
	at org.eclipse.osgi.internal.hooks.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:107)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClass(ClasspathManager.java:529)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.findLocalClass(ModuleClassLoader.java:325)
	at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:345)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:423)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:372)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:364)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:161)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at org.eclipse.osgi.internal.framework.EquinoxBundle.loadClass(EquinoxBundle.java:564)
	at org.eclipse.core.internal.registry.osgi.RegistryStrategyOSGI.createExecutableExtension(RegistryStrategyOSGI.java:174)
	at org.eclipse.core.internal.registry.ExtensionRegistry.createExecutableExtension(ExtensionRegistry.java:905)
	at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:243)
	at org.eclipse.core.internal.registry.ConfigurationElementHandle.createExecutableExtension(ConfigurationElementHandle.java:55)
	at org.eclipse.jdt.internal.ui.text.java.hover.JavaEditorTextHoverDescriptor.createTextHover(JavaEditorTextHoverDescriptor.java:120)
	at org.eclipse.jdt.internal.ui.text.java.hover.BestMatchHover.checkTextHovers(BestMatchHover.java:83)
	at org.eclipse.jdt.internal.ui.text.java.hover.BestMatchHover.getHoverInfo2(BestMatchHover.java:152)
	at org.eclipse.jdt.internal.ui.text.java.hover.BestMatchHover.getHoverInfo2(BestMatchHover.java:130)
	at org.eclipse.jdt.internal.ui.text.java.hover.JavaEditorTextHoverProxy.getHoverInfo2(JavaEditorTextHoverProxy.java:86)
	at org.eclipse.jface.text.TextViewerHoverManager$4.run(TextViewerHoverManager.java:165)

eclipse.buildId=4.6.1.M20160907-1200
java.version=1.8.0_111
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=en_US
Framework arguments:  -product org.eclipse.epp.package.jee.product -product org.eclipse.epp.package.jee.product -product org.eclipse.epp.package.jee.product
Command-line arguments:  -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.jee.product -product org.eclipse.epp.package.jee.product -data file:/C:/Users/Kiril_Akshonau/workspace/ -product org.eclipse.epp.package.jee.product

org.eclipse.osgi
Warning
Thu Dec 01 17:07:56 MSK 2016
While loading class "org.eclipse.egit.ui.internal.ConfigurationChecker$1$1", thread "Thread[Worker-2,5,main]" timed out waiting (5625ms) for thread "Thread[main,6,main]" to finish starting bundle "org.eclipse.egit.ui_4.5.0.201609210915-r [350]". To avoid deadlock, thread "Thread[Worker-2,5,main]" is proceeding but "org.eclipse.egit.ui.internal.ConfigurationChecker$1$1" may not be fully initialized.

org.osgi.framework.BundleException: Unable to acquire the state change lock for the module: osgi.identity; type="osgi.bundle"; version:Version="4.5.0.201609210915-r"; osgi.identity="org.eclipse.egit.ui"; singleton:="true" [id=350] STARTED [STARTED]
	at org.eclipse.osgi.container.Module.lockStateChange(Module.java:337)
	at org.eclipse.osgi.container.Module.start(Module.java:401)
	at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:470)
	at org.eclipse.osgi.internal.hooks.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:107)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClass(ClasspathManager.java:529)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.findLocalClass(ModuleClassLoader.java:325)
	at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:345)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:423)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:372)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:364)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:161)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at org.eclipse.egit.ui.internal.ConfigurationChecker$1.run(ConfigurationChecker.java:45)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)
Caused by: java.util.concurrent.TimeoutException: Timeout after waiting 5 seconds to acquire the lock.
	at org.eclipse.osgi.container.Module.lockStateChange(Module.java:334)
	... 13 more
Root exception:
java.util.concurrent.TimeoutException: Timeout after waiting 5 seconds to acquire the lock.
	at org.eclipse.osgi.container.Module.lockStateChange(Module.java:334)
	at org.eclipse.osgi.container.Module.start(Module.java:401)
	at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:470)
	at org.eclipse.osgi.internal.hooks.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:107)
	at org.eclipse.osgi.internal.loader.classpath.ClasspathManager.findLocalClass(ClasspathManager.java:529)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.findLocalClass(ModuleClassLoader.java:325)
	at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:345)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:423)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:372)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:364)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:161)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at org.eclipse.egit.ui.internal.ConfigurationChecker$1.run(ConfigurationChecker.java:45)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)

eclipse.buildId=4.6.1.M20160907-1200
java.version=1.8.0_111
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=en_US
Framework arguments:  -product org.eclipse.epp.package.jee.product -product org.eclipse.epp.package.jee.product
Command-line arguments:  -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.jee.product -data file:/C:/Users/Kiril_Akshonau/workspace/ -product org.eclipse.epp.package.jee.product

org.eclipse.e4.ui.workbench
Warning
Thu Dec 01 17:04:22 MSK 2016
Removing part descriptor with the 'org.codehaus.groovy.eclipse.astviews.ASTView' id and the 'Groovy AST Viewer' description. Points to the invalid 'bundleclass://org.eclipse.ui.workbench/org.eclipse.ui.internal.e4.compatibility.CompatibilityView' class.

[eric-milles]

Can you retest with the latest snapshot?

[kiril-akshonau]

Still Type mismatch: cannot convert from Optional<Object> to <unknown>

[eric-milles]

Thanks for checking. I do not get the error on my Oxygen build. I'll push for Neon.2 JDT core patch this week.

[eric-milles]

Can you retest with the latest snapshot?

[kiril-akshonau]

Thanks a lot @eric-milles. That was really annoying issue. It's fixed and can be closed now