Lambda can only be used with functional interface?

Question

I did this:

public class LambdaConflict
{
    public static void main(String args[]){
        //*
        System.out.println(LambdaConflict.get(
                     


        

Answer 1

No. There is no way to "overcome" this. A functional interface must have only one abstract method. Your interface has two:

interface Intf {
    public T get1(T arg1);
    public T get2(T arg1);
}

Note: You don't need to annotate your interface as mentioned in comments. But you can use the @FunctionalInterface annotation to get compile time errors if your interface is not a valid functional interface. So it brings you a little bit more security in your code.

For more see e.g. http://java.dzone.com/articles/introduction-functional-1