I'm not sure if you're wanting to pass in a class or a function, but here goes both:

In Kotlin you would do something like this (I'm just adding it here for reference, I'm translating backwards from Kotlin to Java since my Java is a bit rusty):

fun foo(m: String, bar: (m: String) -> Unit) {
    bar(m)
}

fun buz1(m: String) {
    println("message1: $m")
}

fun buz2(m: String) {
    println("message2: $m")
}

fun something() {
    foo("hi", this::buz1)
    foo("hi", this::buz2)
}

In Java8+ you would use Lambdas:

public void foo(String m, Function<String, Void> bar) {
    bar.apply(m);
}

// this should be defined somewhere in a class
Function<String, Void> buz1 = (String m) -> {
    System.out.println("message1: " + m);
    return null;
};

// this should be defined somewhere in a class
Function<String, Void> buz2 = (String m) -> {
    System.out.println("message2: " + m);
    return null;
};

void something() {
    foo("test", buz1);
    foo("test", buz2);
}

For passing a class in instead of a function, you'd do something like this in Java

foo("Hello", String.class);

public void foo(String m, Class clazz) {
    System.out.println("Hello " + clazz.getName());
}

From that clazz variable, you can now get all the methods, getters and setters, constructors, etc and then call it dynamically. Do a search for Java Reflection to learn more about how to dynamically call methods in Java given only a method name.

Hope it answers your question.