README quickstart `Filtered<>` snippet compares `String.equals(long)` and ignores `Wallet.id() throws IOException`

[edmoffo]

The "All you need is this" snippet at README.md lines 38-44 builds a Filtered<> predicate that calls w.id() and asks it to equal the literal string "9999888877776666". Wallet.id() is declared in src/main/java/io/zold/api/Wallet.java line 45 as long id() throws IOException, so the example has two defects.

First, the predicate body never matches. "9999888877776666".equals(w.id()) autoboxes the primitive long to a Long, and String.equals(Long) returns false for every wallet in the directory. The iterator's next() call therefore throws NoSuchElementException instead of returning a wallet.

Second, the snippet does not compile as written. Wallet.id() declares throws IOException, but org.cactoos.iterable.Filtered takes a plain Func<X, Boolean>. A lambda that calls a method throwing a checked exception needs IoCheckedFunc or a wrapper, neither of which the example uses.

Smallest fix: drop the quotes, parse the id as hex, and either use IoCheckedFunc or replace Filtered with the cactoos iterable that tolerates IOException. For example:

final long target = Long.parseUnsignedLong("9999888877776666", 16);
final Wallet wallet = new Filtered<>(
    new IoCheckedFunc<>(w -> w.id() == target),
    wallets
).iterator().next();

That keeps the README example honest about both the id type and the checked exception surface.

[edmoffo]

@yegor256 happy to clarify the example or expand on the proposed fix.