Created attachment 157695 [details]
stacktrace

Created attachment 157696 [details]
dump file mentioned in the exception dialog

Created attachment 157698 [details]
IDE log

Created attachment 157834 [details]
stacktrace

Happened during code completion

Created attachment 157845 [details]
stacktrace

Happened during code completion of JsonObject

Created attachment 158215 [details]
stacktrace

Happened during annotating an annotation (typing @)

This bug already has 5 duplicates 
see http://statistics.netbeans.org/exceptions/detail.do?id=221545

Created attachment 158296 [details]
stacktrace

I was typing inside of a newly-added JPA @Query annotation when the error message came up.

Created attachment 158411 [details]
stacktrace

Opened file in Java editor. Exception thrown.

This bug already has 20 duplicates 
see http://statistics.netbeans.org/exceptions/detail.do?id=221545

Dusan,

This exception is taking down the entire IDE. If I code-format after saving code that generates this exception, the Swing thread hangs (indefinitely) running some endless task and I am forced to kill the process. This is 100% reproducible.

Product Version: NetBeans IDE Dev (Build 201605170002)
Java: 1.8.0_92; Java HotSpot(TM) 64-Bit Server VM 25.92-b14
Runtime: Java(TM) SE Runtime Environment 1.8.0_92-b14
System: Windows 10 version 10.0 running on amd64; Cp1252; en_CA (nb)
User directory: C:\Users\Gili\AppData\Roaming\NetBeans\dev
Cache directory: C:\Users\Gili\AppData\Local\NetBeans\Cache\dev

Repro steps:

1. Create new Maven Java project
2. Create a new class and save it:

package websitemonitor.backend.entity;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonValue;
import com.google.common.collect.ImmutableList;
import com.vtlr.backend.ToJsonString;
import java.net.URI;
import java.util.List;
import org.bitbucket.cowwoc.preconditions.Preconditions;

/**
 * A collection of pages.
 * <p>
 * @author Gili Tzabari
 */
public final class PagesEntities
{
	/**
	 * The content-type of the JSON representation of this resource.
	 */
	public static final String JSON_TYPE = "application/x-websitemonitor.Pages+json; version=1; charset=utf-8";

	/**
	 * The entity returned by HTTP GET uri:pages.
	 */
	public static final class GetPages
	{
	/**
	 * The address of the page.
	 */
	private final URI uri;
	/**
	 * The canonical address of the page.
	 */
	private final URI canonicalUri;
	/**
	 * Indicates how long it took for the page to load.
	 */
	private final Duration loadTime;
	/**
	 * The HTTP status code returned when loading the page.
	 */
	private final int statusCode;
	/**
	 * Links that refer to malformed URLs.
	 */
	private final List<String> invalidLinks = new ArrayList<>();
	/**
	 * Links that refer to well-formed URLs.
	 */
	private final List<URI> validLinks = new ArrayList<>();

		/**
		 * Creates a new GetCompanies.
		 * <p>
		 * @param companies the list of companies
		 * @throws NullPointerException if companies is null
		 */
		@JsonCreator
		public GetCompanies(List<URI> companies)
			throws NullPointerException
		{
			Preconditions.requireThat(companies, "companies").isNotNull();

			this.companies = ImmutableList.copyOf(companies);
		}

		/**
		 * @return the list of companies
		 */
		@JsonValue
		@SuppressWarnings("ReturnOfCollectionOrArrayField")
		public List<URI> getCompanies()
		{
			return companies;
		}

		@Override
		public String toString()
		{
			return new ToJsonString(getClass(), this).toString();
		}
	}

	/**
	 * Prevent construction.
	 */
	private CompaniesEntities()
	{
	}
}

3. Netbeans will throw the following exception:

java.lang.NullPointerException
	at com.sun.tools.javac.code.TypeAnnotations$TypeAnnotationPositions.visitMethodDef(TypeAnnotations.java:1141)
	at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:842)
	at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
	at com.sun.tools.javac.code.TypeAnnotations$TypeAnnotationPositions.scan(TypeAnnotations.java:286)
	at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:57)
	at com.sun.tools.javac.code.TypeAnnotations$TypeAnnotationPositions.visitClassDef(TypeAnnotations.java:1120)
	at com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:748)
	at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
	at com.sun.tools.javac.code.TypeAnnotations$TypeAnnotationPositions.scan(TypeAnnotations.java:286)
	at com.sun.tools.javac.code.TypeAnnotations$1.run(TypeAnnotations.java:124)
	at com.sun.tools.javac.comp.Annotate.flush(Annotate.java:179)
	at com.sun.tools.javac.comp.Annotate.unblockAnnotations(Annotate.java:130)
	at com.sun.tools.javac.comp.Enter.complete(Enter.java:738)
	at org.netbeans.lib.nbjavac.services.NBJavadocEnter.main(NBJavadocEnter.java:84)
	at com.sun.tools.javac.main.JavaCompiler.enterTrees(JavaCompiler.java:995)
	at com.sun.tools.javac.api.JavacTaskImpl.enter(JavacTaskImpl.java:369)
	at com.sun.tools.javac.api.JavacTaskImpl.enter(JavacTaskImpl.java:311)
	at org.netbeans.modules.java.source.parsing.JavacParser.moveToPhase(JavacParser.java:630)
	at org.netbeans.modules.java.source.parsing.JavacParser.getResult(JavacParser.java:496)
	at org.netbeans.modules.java.source.parsing.JavacParser.getResult(JavacParser.java:163)
	at org.netbeans.modules.parsing.impl.TaskProcessor.callGetResult(TaskProcessor.java:631)
	at org.netbeans.modules.parsing.impl.SourceCache.getResult(SourceCache.java:262)
	at org.netbeans.modules.parsing.impl.TaskProcessor$RequestPerformer.run(TaskProcessor.java:798)
	at org.openide.util.lookup.Lookups.executeWith(Lookups.java:304)
	at org.netbeans.modules.parsing.impl.TaskProcessor$RequestPerformer.execute(TaskProcessor.java:725)
[catch] at org.netbeans.modules.parsing.impl.TaskProcessor$CompilationJob.run(TaskProcessor.java:686)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1443)
	at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:68)
	at org.openide.util.lookup.Lookups.executeWith(Lookups.java:303)
	at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2058)

4. Close the Exception Reporter dialog.
5. Invoke code-format.
6. Save the file.
7. IDE will hang indefinitely. Process must be killed.

This is 100% reproducible.

Fixed in jet-main.

http://hg.netbeans.org/jet-main/rev/5a6f2b6ec074
http://hg.netbeans.org/main/nb-javac/rev/e63522d2d8d2

Dusan,

What about the bigger bug of the IDE hanging if a parsing error occuring? Did you take a look at that?

Integrated into 'main-silver', will be available in build *201605260002* on http://bits.netbeans.org/dev/nightly/ (upload may still be in progress)

Changeset: http://hg.netbeans.org/main-silver/rev/5a6f2b6ec074
User: Dusan Balek <dbalek@netbeans.org>
Log: Issue #257020 - NullPointerException at com.sun.tools.javac.code.TypeAnnotations$TypeAnnotationPositions.visitMethodDef - fixed.

Thanks. Verified as fixed 
Product Version: NetBeans IDE Dev (Build 201606010002)