Methods · Scala Universe

Lookup

Public in the hierarchy, or anything on the class

findMethod matches public methods like Class.getMethod, inherited ones included. findDeclaredMethod finds any method of the class itself, private ones included. Parameters are given as erased classes.

class User(val name: String) { def greeting(prefix: String): String = s"$prefix $name" private def secret(): String = "hidden" } val user = TypeResolver.resolve(classOf[User]) println(user.findMethod("greeting", classOf[String]).returnType.name) // String println(user.findMethod("secret")) // null println(user.findDeclaredMethod("secret").name) // secret

Overrides

One entry per signature

overrides lists the methods of supertypes with the same name and parameter types. methods leaves every one of them out, so iterating methods never sees a signature twice.

trait Greeter { def greet(name: String): String } class Polite extends Greeter { def greet(name: String) = s"Good day, $name" } val greet = TypeResolver.resolve(classOf[Polite]).findMethod("greet", classOf[String]) println(greet.owner.name) // Polite println(greet.overrides.map(_.owner.name).mkString(", ")) // Greeter

Annotations from the interface

annotations of a method includes the declared annotations of everything it overrides. An annotation on the trait's method is found on the implementation.

Invocation

invoke

invoke makes the method accessible and calls it with the given arguments. Exceptions thrown by the method arrive wrapped in InvocationTargetException, as with plain reflection.

val ada = new User("Ada") println(user.findMethod("greeting", classOf[String]).invoke(ada, "Hello")) // Hello Ada println(user.findDeclaredMethod("secret").invoke(ada)) // hidden

Scala

What methods a Scala class has

Accessors, setters and compiler-generated members are ordinary methods to the JVM and appear in methods.

val name: Method name().
var name: Methods name() and name_$eq(value).
case class: copy, productArity, productElement, equals, hashCode, toString and _1, _2 …
default arguments: Methods like greeting$default$1 for each default.