Resumindo os comentários acima, a solução avançada é usar um wrapper especial para funções não verificadas com o construtor como API, que fornece recuperação, nova exibição e supressão.
Stream.of("java.lang.Object", "java.lang.Integer", "java.lang.String")
.map(Try.<String, Class<?>>safe(Class::forName)
.handle(System.out::println)
.unsafe())
.collect(toList());
O código abaixo demonstra para interfaces de consumidor, fornecedor e função. Pode ser facilmente expandido. Algumas palavras-chave públicas foram removidas para este exemplo.
Classe Try é o ponto final para o código do cliente. Métodos seguros podem ter um nome exclusivo para cada tipo de função.
CheckedConsumer , CheckedSupplier e CheckedFunction são análogos verificados das funções lib que podem ser usadas independentemente do Try
CheckedBuilder é a interface para lidar com exceções em alguma função marcada. ouTry permite executar outra função do mesmo tipo, se houver falha anterior. handle fornece tratamento de exceção, incluindo filtragem de tipo de exceção. A ordem dos manipuladores é importante. Reduzir métodos inseguros e relançar relança última exceção na cadeia de execução. Reduza os métodos orElse e orElseGet retornam valores alternativos, como opcionais, se todas as funções falharem. Também existe o método suprimir . CheckedWrapper é a implementação comum do CheckedBuilder.
final class Try {
public static <T> CheckedBuilder<Supplier<T>, CheckedSupplier<T>, T>
safe(CheckedSupplier<T> supplier) {
return new CheckedWrapper<>(supplier,
(current, next, handler, orResult) -> () -> {
try { return current.get(); } catch (Exception ex) {
handler.accept(ex);
return next.isPresent() ? next.get().get() : orResult.apply(ex);
}
});
}
public static <T> Supplier<T> unsafe(CheckedSupplier<T> supplier) {
return supplier;
}
public static <T> CheckedBuilder<Consumer<T>, CheckedConsumer<T>, Void>
safe(CheckedConsumer<T> consumer) {
return new CheckedWrapper<>(consumer,
(current, next, handler, orResult) -> t -> {
try { current.accept(t); } catch (Exception ex) {
handler.accept(ex);
if (next.isPresent()) {
next.get().accept(t);
} else {
orResult.apply(ex);
}
}
});
}
public static <T> Consumer<T> unsafe(CheckedConsumer<T> consumer) {
return consumer;
}
public static <T, R> CheckedBuilder<Function<T, R>, CheckedFunction<T, R>, R>
safe(CheckedFunction<T, R> function) {
return new CheckedWrapper<>(function,
(current, next, handler, orResult) -> t -> {
try { return current.applyUnsafe(t); } catch (Exception ex) {
handler.accept(ex);
return next.isPresent() ? next.get().apply(t) : orResult.apply(ex);
}
});
}
public static <T, R> Function<T, R> unsafe(CheckedFunction<T, R> function) {
return function;
}
@SuppressWarnings ("unchecked")
static <T, E extends Throwable> T throwAsUnchecked(Throwable exception) throws E {
throw (E) exception;
}
}
@FunctionalInterface interface CheckedConsumer<T> extends Consumer<T> {
void acceptUnsafe(T t) throws Exception;
@Override default void accept(T t) {
try { acceptUnsafe(t); } catch (Exception ex) {
Try.throwAsUnchecked(ex);
}
}
}
@FunctionalInterface interface CheckedFunction<T, R> extends Function<T, R> {
R applyUnsafe(T t) throws Exception;
@Override default R apply(T t) {
try { return applyUnsafe(t); } catch (Exception ex) {
return Try.throwAsUnchecked(ex);
}
}
}
@FunctionalInterface interface CheckedSupplier<T> extends Supplier<T> {
T getUnsafe() throws Exception;
@Override default T get() {
try { return getUnsafe(); } catch (Exception ex) {
return Try.throwAsUnchecked(ex);
}
}
}
interface ReduceFunction<TSafe, TUnsafe, R> {
TSafe wrap(TUnsafe current, Optional<TSafe> next,
Consumer<Throwable> handler, Function<Throwable, R> orResult);
}
interface CheckedBuilder<TSafe, TUnsafe, R> {
CheckedBuilder<TSafe, TUnsafe, R> orTry(TUnsafe next);
CheckedBuilder<TSafe, TUnsafe, R> handle(Consumer<Throwable> handler);
<E extends Throwable> CheckedBuilder<TSafe, TUnsafe, R> handle(
Class<E> exceptionType, Consumer<E> handler);
CheckedBuilder<TSafe, TUnsafe, R> handleLast(Consumer<Throwable> handler);
<E extends Throwable> CheckedBuilder<TSafe, TUnsafe, R> handleLast(
Class<E> exceptionType, Consumer<? super E> handler);
TSafe unsafe();
TSafe rethrow(Function<Throwable, Exception> transformer);
TSafe suppress();
TSafe orElse(R value);
TSafe orElseGet(Supplier<R> valueProvider);
}
final class CheckedWrapper<TSafe, TUnsafe, R>
implements CheckedBuilder<TSafe, TUnsafe, R> {
private final TUnsafe function;
private final ReduceFunction<TSafe, TUnsafe, R> reduceFunction;
private final CheckedWrapper<TSafe, TUnsafe, R> root;
private CheckedWrapper<TSafe, TUnsafe, R> next;
private Consumer<Throwable> handlers = ex -> { };
private Consumer<Throwable> lastHandlers = ex -> { };
CheckedWrapper(TUnsafe function,
ReduceFunction<TSafe, TUnsafe, R> reduceFunction) {
this.function = function;
this.reduceFunction = reduceFunction;
this.root = this;
}
private CheckedWrapper(TUnsafe function,
CheckedWrapper<TSafe, TUnsafe, R> prev) {
this.function = function;
this.reduceFunction = prev.reduceFunction;
this.root = prev.root;
prev.next = this;
}
@Override public CheckedBuilder<TSafe, TUnsafe, R> orTry(TUnsafe next) {
return new CheckedWrapper<>(next, this);
}
@Override public CheckedBuilder<TSafe, TUnsafe, R> handle(
Consumer<Throwable> handler) {
handlers = handlers.andThen(handler);
return this;
}
@Override public <E extends Throwable> CheckedBuilder<TSafe, TUnsafe, R>
handle(Class<E> exceptionType, Consumer<E> handler) {
handlers = handlers.andThen(ex -> {
if (exceptionType.isInstance(ex)) {
handler.accept(exceptionType.cast(ex));
}
});
return this;
}
@Override public CheckedBuilder<TSafe, TUnsafe, R> handleLast(
Consumer<Throwable> handler) {
lastHandlers = lastHandlers.andThen(handler);
return this;
}
@Override public <E extends Throwable> CheckedBuilder<TSafe, TUnsafe, R>
handleLast(Class<E> exceptionType, Consumer<? super E> handler) {
lastHandlers = lastHandlers.andThen(ex -> {
if (exceptionType.isInstance(ex)) {
handler.accept(exceptionType.cast(ex));
}
});
return this;
}
@Override public TSafe unsafe() {
return root.reduce(ex -> Try.throwAsUnchecked(ex));
}
@Override
public TSafe rethrow(Function<Throwable, Exception> transformer) {
return root.reduce(ex -> Try.throwAsUnchecked(transformer.apply(ex)));
}
@Override public TSafe suppress() {
return root.reduce(ex -> null);
}
@Override public TSafe orElse(R value) {
return root.reduce(ex -> value);
}
@Override public TSafe orElseGet(Supplier<R> valueProvider) {
Objects.requireNonNull(valueProvider);
return root.reduce(ex -> valueProvider.get());
}
private TSafe reduce(Function<Throwable, R> orResult) {
return reduceFunction.wrap(function,
Optional.ofNullable(next).map(p -> p.reduce(orResult)),
this::handle, orResult);
}
private void handle(Throwable ex) {
for (CheckedWrapper<TSafe, TUnsafe, R> current = this;
current != null;
current = current.next) {
current.handlers.accept(ex);
}
lastHandlers.accept(ex);
}
}