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

Taking Miguel Gamboa’s solution and trying to minimize the per-field code without sacrificing its elegance, I came to the following solution:

interface Lazy extends Supplier {
    Supplier init();
    public default T get() { return init().get(); }
}
static  Supplier lazily(Lazy lazy) { return lazy; }
static  Supplier value(T value) { return ()->value; }

Supplier fieldBaz = lazily(() -> fieldBaz=value(expensiveInitBaz()));
Supplier fieldGoo = lazily(() -> fieldGoo=value(expensiveInitGoo()));
Supplier fieldEep = lazily(() -> fieldEep=value(expensiveInitEep()));

The per-field code only slightly bigger than in Stuart Marks’s solution but it retains the nice property of the original solution that after the first query, there will be only a lightweight Supplier which unconditionally returns the already computed value.