What are some examples of first-class functions in Java?

What are some examples of first-class functions in Java?

In Java, first-class functions can be represented using functional interfaces and lambda expressions. For example, you can use the Function<T, R> interface to create a function that takes an argument of type T and returns a value of type R.

Can you show me a code example?

Sure! Here's a simple example:

import java.util.function.Function;

public class Main {
    public static void main(String[] args) {
        Function<Integer, Integer> square = x -> x * x;
        System.out.println(square.apply(5)); // Output: 25
    }
}

What about using method references?

Great question! You can use method references to refer to existing methods as functions. For example:

import java.util.function.Function;

public class Main {
    public static void main(String[] args) {
        Function<String, Integer> stringLength = String::length;
        System.out.println(stringLength.apply("Hello")); // Output: 5
    }
}