Updated be the compiler, includes book version

public class BeTheCompiler {

  public static void main(String[] args) {

    Runnable runnable = () -> System.out.println("Hi!");

//    Runnable runnable2 = (String str) -> System.out.println(str);

    Consumer<String> consumer = s -> System.out.println(s);

//    Consumer<String> consumer2 = (str1, str2) -> System.out.println(str1 + ", " + str2);

//    Consumer<String> consumer3 = s -> "String" + s;

//    Supplier<String> supplier3 = () -> System.out.println("Some string");

//    Consumer<String> consumer2 = (s1, s2) -> System.out.println(s1 + s2);

//    Runnable runnable2 = (String str) -> System.out.println(str);

    Function<String, Integer> function = s -> s.length();

    Function<String, Integer> function2 = (String s) -> s.length();

//    Function<String, Integer> function3 = (int i) -> "i = " + i;

    Supplier<String> supplier = () -> "Some string";

//    Consumer<String> consumer3 = s -> "String" + s;

//    Function<String, Integer> function3 = (Integer i) -> "i = " + i;

//    Supplier<String> supplier2 = s -> "Some string: " + s;

//    Supplier<String> supplier3 = () -> System.out.println("Some string");

//    Function<String, Integer> function2 = () -> System.out.println("Some string");

  }

  void book() {

//    ❑Runnable r = () -> System.out.println("Hi!");

//❑Consumer<String> c = s -> System.out.println(s);

//❑Supplier<String> s = () -> System.out.println("Some string");

//❑Consumer<String> c = (s1, s2) -> System.out.println(s1 + s2);

//❑Runnable r = (String str) -> System.out.println(str);

//❑Function<String, Integer> f = s -> s.length();

//❑Supplier<String> s = () -> "Some string";

//❑Consumer<String> c = s -> "String" + s;

//❑Function<String, Integer> f = (int i) -> "i = " + i;

//❑Supplier<String> s = s -> "Some string: " + s;

//❑Function<String, Integer> f = () -> System.out.println("Some string");

  }

}