ラムダ式 ref: http://qiita.com/Yuki_312/items/d14665b53fc6dccf11f4

file0.java

// Java7 non-Lambda
Runnable r = new Runnable() {
  public void run() {
    System.out.println("Howdy, world!");
  }
};
r.run();

// Java8 Lambda
Runnable r2 = () -> System.out.println("Howdy, world!");
r2.run();

file1.java

@FunctionalInterface
interface Hoge {
  public String foo();
}

file2.java

public class Main {
    @FunctionalInterface
    interface Lambda {
        public void print();
    }

    public static void main(String... args) {
        new Main().execute();
    }

    private void execute() {
        new Hoge().foo(() -> System.out.println(this));
    }

}

class Hoge {
    public void foo(Main.Lambda lambda) {
        lambda.print();
    }
}

// 出力結果: Main@5ca881b5
// lambda.print()で得られるthisはHogeではなくMainを指す. 

file3.java

// 出力結果: Main$1@15db9742
public class Main {
    public static void main(String... args) {
        new Main().execute();
    }

    public void execute() {
        Runnable r = new Runnable() {
            public void run() {
                System.out.println(this);
           }
        };
        r.run();
    }
}

// 出力結果: Main@15db9742
public class Main {
    public static void main(String... args) {
        new Main().execute();
    }

    public void execute() {
        Runnable r = ()-> System.out.println(this);
        r.run();
    }
}