Lazy field initialization with lambdas

Question

I would like to implement lazy field initialization (or deferred initialization) without an if statement and taking advantage of lambdas. So, I would like to have the same b

Answer 1

Here's a way that also works if you want to pass arguments (which you dont have when initializing the functional interface) to your expensiveInit method.

public final class Cache {
    private Function, T> supplier;

    private Cache(){
        supplier = s -> {
            T value = s.get();
            supplier = n -> value;
            return value;
        };
    }   
    public static  Supplier of(Supplier creater){
        Cache c = new Cache<>();
        return () -> c.supplier.apply(creater);
    }
    public static  Function of(Function creater){
        Cache c = new Cache<>();
        return u -> c.supplier.apply(() -> creater.apply(u));
    }
    public static  BiFunction of(BiFunction creater){
        Cache c = new Cache<>();
        return (u, v) -> c.supplier.apply(() -> creater.apply(u, v));
    }
}

Usage is the same as Stuart Marks' answer:

private final Function lazyBar = Cache.of(this::expensiveBarForFoo);