Using Scala from Java: passing functions as parameters

Question

Consider the following Scala code:

package scala_java object MyScala {   def setFunc(func: Int => String) {     func(10)   } } 

Now in Java, I would have liked to use MyScala as:

package scala_java; public class MyJava {     public static void main(String [] args) {         MyScala.setFunc(myFunc);  // This line gives an error     }     public static String myFunc(int someInt) {         return String.valueOf(someInt);     } } 

However, the above does not work (as expected since Java does not allow functional programming). What is the easiest workaround to pass a function in Java? I would like a generic solution that works with functions having arbitrary number of parameters.

EDIT: Does Java 8 have any better syntax than the classic solutions discussed below?

Answer 1

In the scala.runtime package, there are abstract classes named AbstractFunction1 and so on for other arities. To use them from Java you only need to override apply, like this:

Function1<Integer, String> f = new AbstractFunction1<Integer, String>() {     public String apply(Integer someInt) {         return myFunc(someInt);     } }; 

If you're on Java 8 and want to use Java 8 lambda syntax for this, check out https://github.com/scala/scala-java8-compat.