Test.java

import java.lang.Math;
import java.util.function.BinaryOperator;
import java.io.*;

// one class needs to have a main() method
public class Test
{
  // arguments are passed using the text field below this editor
  
  
  public static void main(String[] args) throws IOException
  {
    BinaryOperator<String> adder1 = (n1, n2) -> n1 + n2;
    BinaryOperator<String> adder2 = (BinaryOperator<String> & Serializable)((n1, n2) -> n1 + n2);
    System.out.println(adder1.getClass().getInterfaces());
    System.out.println(adder2.getClass().getInterfaces());
    ObjectOutputStream output = new ObjectOutputStream(new FileOutputStream(new File("lambdas")));
    try {
        output.writeObject(adder1);
    } catch (java.io.NotSerializableException e){
        System.out.println("As expected");
    }
    output.writeObject(adder2);
    output.close();
  }
}