How to find functional interface candidates in IntelliJ - intellij-idea

Question

I'm trying to use search structurally to find interfaces that could be annotated with #FunctionalInterface since they only contain a single abstract method but aren't annotated yet.
My current structural search template looks like this:
#$TheAnnotation$
interface $Interface$ {
$ReturnType$ $Method$ ($ParameterType$ $Parameter$);
}
I've added the following filters
Parameters: count -> [0, ∞]
TheAnnotation: script -> TheAnnotation.getClass() != FunctionalInterface.class
but that does not seem to work as the result will contain classes annotated with #FunctionalInterface nevertheless.

Answer 1

IntelliJ IDEA has a "Interface may be annotated #FunctionalInterface" inspection, you may want to use instead. It has a quick fix to add the #FunctionalInteface annotation.
But if you insist on using Structural Search, here's a template that should work:
<searchConfiguration name="Unnamed" text="#$TheAnnotation$
interface $Interface$ {
abstract $ReturnType$ $Method$ ($ParameterType$ $Parameter$);
abstract $ReturnType2$ $Method2$ ($ParameterType2$ $Parameter2$);
}" recursive="false" caseInsensitive="false" type="JAVA" pattern_context="default">
<constraint name="__context__" within="" contains="" />
<constraint name="TheAnnotation" regexp="FunctionalInterface" minCount="0" maxCount="0" within="" contains="" />
<constraint name="Method" within="" contains="" />
<constraint name="Interface" within="" contains="" />
<constraint name="ReturnType" within="" contains="" />
<constraint name="ReturnType2" within="" contains="" />
<constraint name="ParameterType" within="" contains="" />
<constraint name="ParameterType2" within="" contains="" />
<constraint name="Parameter" minCount="0" maxCount="2147483647" within="" contains="" />
<constraint name="Parameter2" minCount="0" maxCount="2147483647" within="" contains="" />
<constraint name="Method2" minCount="0" maxCount="0" within="" contains="" />
</searchConfiguration>
(copy the xml and using the "Import Template from Clipboard" action under the tool button in the Structural Search dialog)