How can I store a method in a variable in Java 8?

Question

Is it possible to store a method into a variable? Something like

 public void store() {
     SomeClass foo = ;
     //...
     String          


        

Answer 1

You can use Java 8 method references. You can use the :: 'operator' to grab a method reference from an object.

import java.util.function.IntConsumer;

class Test {
    private int i;
    public Test() { this.i = 0; }
    public void inc(int x) { this.i += x; }
    public int get() { return this.i; }

    public static void main(String[] args) {
        Test t = new Test();
        IntConsumer c = t::inc;
        c.accept(3);
        System.out.println(t.get());
        // prints 3
    }
}

You just need a @FunctionalInterface that matches the signature of the method you want to store. java.util.function contains a selection of the most commonly used ones.