Unknown function 'org.neo4j.examples.join' on neo4j - neo4j

Question

I am trying to creating user defined procedure.
i got the sample project from this github repository https://github.com/neo4j-examples/neo4j-procedure-template. i created the jar file and moved to /var/lib/neo4j/plugins
i am getting the unknown function error
If anyone knows about it help me please
also i restarted my neo4j also
neo4j> MATCH (p: Person) WHERE p.age = 36 RETURN org.neo4j.examples.join(collect(p.names));
Unknown function 'org.neo4j.examples.join' (line 1, column 44 (offset: 43))
"MATCH (p: Person) WHERE p.age = 36 RETURN org.neo4j.examples.join(collect(p.names));"

Answer 1

If you look at the comment on the java method for this function, you will see into the description annotation, that to call it you should do : example.join(...) and NOT org.neo4j.examples.join.
This function is under the java package example, and the name of the function is join, so it gives you example.join
You can define manually what is the way to call a function by adding a name attribut into the UserFunction annotation. Like this :
#UserFunction( "test.nodeList" )
public List<Object> nodeList()
{
Result result = db.execute( "MATCH (n) RETURN n LIMIT 1" );
Object node = result.next().get( "n" );
return Collections.singletonList( node );
}
And call it in cypher like this :
RETURN test.toSet(['a', 'b'])