JavaLambdaAsParameterExample.java

class Programmer {
    private String name;
    
    public Programmer(String name) {
        this.name = name;
    }

    public String getName() {
        return this.name;
    }

    public void announce() {
        System.out.println("I am a Programmer and my name is " + name);
    }
}

class Pair {
    private Programmer leftPerson;
    private Programmer rightPerson;

    public Pair(Programmer leftPerson, Programmer rightPerson) {
        this.leftPerson = leftPerson;
        this.rightPerson = rightPerson;
    }

    public void announce() {
        System.out.println("We are pair-programming and our names are " +
                           this.leftPerson.getName() +
                           " and " +
                           this.rightPerson.getName());
    }        
}

interface MockPopulator {
    public void createMocksForPair(Programmer one, Programmer two);
}

public class JavaLambdaAsParameterExample {

    private Pair createSamplePair(MockPopulator populator) {
        Programmer mike = new Programmer("Mike");
        Programmer giules = new Programmer("Giules");
        Pair pair = new Pair(mike, giules);

        populator.createMocksForPair(mike, giules);

        return pair;
    }

    public void doTheThing() {
        Pair pair = createSamplePair((left, right) -> {
            left.announce();
            right.announce();
        });

        pair.announce();
    }
    
    public static void main(String[] args) {
        JavaLambdaAsParameterExample sample = new JavaLambdaAsParameterExample();
        sample.doTheThing();
    }
}

Output:

[rmrogers@Cobbler]~/Documents/Projects$ java JavaLambdaAsParameterExample 
I am a Programmer and my name is Mike
I am a Programmer and my name is Giules
We are pair-programming and our names are Mike and Giules