Foo.java

/**
 * http://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.13.1
 */


import java.util.ArrayList;
import java.util.List;

public class Foo {

    public static void main(String[] args) {


        List<Bar> l = new ArrayList<>();

        l.add(new Bar());
        l.add(new Bar());
        l.add(new Bar());

        l.stream()
                .peek(Bar::print)  // error: invalid method reference
                                   // non-static method print() cannot be referenced from a static context
                .forEach(Bar::print);  // error: invalid method reference
                                       // non-static method print() cannot be referenced from a static context


        Bar b = new Bar();
        b.print();
        Bar.print(b);

    }

}

class Bar {

    public void print() {
        System.out.println("this: " + this);
    }

    public static void print(Bar b) {
        System.out.println("bar: " + b);
    }

}