Shawn, Thanks for the response! Yes, that was it, an older version unexpectedly in the classpath.
And for the benefit of anyone who searches the list archive with a similar debugging need, it's pretty easy to print out the classpath from ant's build.xml: <path id="classpath"> <pathelement location="${builddir}/common"/> <fileset dir="${builddir}/deps/"><include name="**/*.jar"/></fileset> <fileset dir="libs"><include name="**/*.jar"/></fileset> <fileset erroronmissingdir="false" dir="${solr.dir}"><include name="**/*.jar"/></fileset> <fileset erroronmissingdir="false" dir="${vufind.dir}/solr/vendor/dist"><include name="**/*.jar"/></fileset> <fileset erroronmissingdir="false" dir="${vufind.dir}/solr/vendor/server/solr-webapp/webapp/WEB-INF/lib"><include name="**/*.jar"/></fileset> </path> <!-- Can be useful for debugging --> <pathconvert property="classpathProp" refid="classpath"/> <echo>Classpath: ${classpathProp}</echo> -Tod On Nov 29, 2017, at 6:00 PM, Shawn Heisey <apa...@elyograg.org<mailto:apa...@elyograg.org>> wrote: On 11/29/2017 2:27 PM, Tod Olson wrote: I'm modifying a existing custom request handler for an open source project, and am looking for some help with a compile error around an anonymous SimpleCollector. The build failure message from ant and the source of the specific method are below. I am compiling on a Mac with Java 1.8 and Solr 6.4.2. There are two things I do not understand. First: [javac] /Users/tod/src/vufind-browse-handler/browse-handler/java/org/vufind/solr/handler/BrowseRequestHandler.java:445: error: <anonymous org.vufind.solr.handler.BibDB$1> is not abstract and does not override abstract method setNextReader(AtomicReaderContext) in Collector [javac] db.search(q, new SimpleCollector() { Based on the javadoc, neither SimpleCollector nor Collector define a setNextReader(AtomicReaderContext) method. Grepping through the Lucene 6.4.2 source reveals neither a setNextReader method (though maybe a couple archaic comments), nor an AtomicReaderContext class or interface. <snip> Second: [javac] method IndexSearcher.search(Query,Collector) is not applicable [javac] (argument mismatch; <anonymous SimpleCollector> cannot be converted to Collector) How is it that SimpleCollector cannot be converted to Collector? Perhaps this is just a consequence of the first error. For the first error: What version of Solr/Lucene are you compiling against? I have found that Collector *did* have a setNextReader method up through Lucene 4.10.4, but in 5.0, that method was gone. I suspect that what's causing your first problem is that you have older Lucene jars (4.x or earlier) on your classpath, in addition to a newer version that you actually want to use for the compile. I think that can also explain the second problem. It looks like SimpleCollector didn't exist in Lucene 4.10, which is the last version where Collector had setNextReader. SimpleCollector is mentioned in the javadoc for Collector as of 5.0, though. Thanks, Shawn