Java Pass Method as Parameter

Question

I am looking for a way to pass a method by reference. I understand that Java does not pass methods as parameters, however, I would like to get an alternative.

I\'ve

Answer 1

I didn't find any example explicit enough for me on how to use java.util.function.Function for simple method as parameter function. Here is a simple example:

import java.util.function.Function;

public class Foo {

  private Foo(String parameter) {
    System.out.println("I'm a Foo " + parameter);
  }

  public static Foo method(final String parameter) {
    return new Foo(parameter);
  }

  private static Function parametrisedMethod(Function function) {
    return function;
  }

  public static void main(String[] args) {
    parametrisedMethod(Foo::method).apply("from a method");
  }
}

Basically you have a Foo object with a default constructor. A method that will be called as a parameter from the parametrisedMethod which is of type Function.

• Function means that the function takes a String as parameter and return a Foo.
• The Foo::Method correspond to a lambda like x -> Foo.method(x);
• parametrisedMethod(Foo::method) could be seen as x -> parametrisedMethod(Foo.method(x))
• The .apply("from a method") is basically to do parametrisedMethod(Foo.method("from a method"))

Which will then return in the output:

>> I'm a Foo from a method

The example should be running as is, you can then try more complicated stuff from the above answers with different classes and interfaces.