MethodReference.java

import java.util.function.BiConsumer;
import java.util.Arrays;
import java.util.List;

class SimpleClass {
    void methodA(String a, String b) {
        System.out.printf("%s %s%n", a, b);
    }
}

class B {
    void different(String x, String y) {
        System.out.println( 
            new StringBuilder(y).append(x).reverse().toString() 
        );
    }
}
class Service {

    void doService(List<BiConsumer<String,String>> methods ) {
        // this is equivalent to the 'for' below
        methods.forEach( item -> item.accept("hello", "world"));
        //for( BiConsumer<String,String> item : methods ) {
        //    item.accept("Hello", "world");
        //}
    }
}

class Main {

    public static void main( String ... args ) { 
        SimpleClass sc = new SimpleClass();
        B b = new B();

        Service s = new Service();

        List<BiConsumer<String,String>> collection = Arrays.asList(
                sc::methodA, 
                b::different
        );

        s.doService( collection ); 
    }
}