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submitted 1 year ago by Threen@aussie.zone to c/java@lemmy.ml

I am wondering if anyone can help me.

I have an issue with compiling some code in Eclipse but not with IntelliJ or javac.

I am using sneakyThrow to bubble a checked exception up through 2 streams.

Here is the smallest reproducible code I can make:

import java.io.IOException;
import java.util.List;
import java.util.function.Predicate;
import java.util.stream.Collectors;

public class Example {
	public static void main(String[] args)
	throws IOException {
		List<List<Integer>> input = List.of(List.of(1, 2), List.of(2, 4));

		// Should return any List whose elements are all even.
		List<List<Integer>> output = input.stream()
			.filter(bubblePredicate(o -> o.stream()
				.allMatch(bubblePredicate(i -> {
					if (i > 10) {
						throw new IOException("Number too large.");
					}
					return i % 2 == 0;
				}))))
			.collect(Collectors.toList());

		System.out.println(output);
	}

	private interface ThrowingPredicate<S, E extends Exception> {
		boolean test(S s) throws E;
	}

	private static <S, E extends Exception> Predicate<S> bubblePredicate(ThrowingPredicate<S, E> callable)
	throws E {
		return s -> {
			try {
				return callable.test(s);
			}
			catch (Exception e) {
				sneakyThrow(e);
				return false;
			}
		};
	}

	private static <E extends Throwable> void sneakyThrow(Exception exception)
	throws E {
		throw (E)exception;
	}
}

Compiles and runs completely fine with javac 11.0.12, but doesn't on Eclipse 4.21.0.I20210906-0500 nor Eclipse 4.27.0.20230309-1200.

Has anyone encountered this before, or have any idea what I am misunderstanding?

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[-] LarsTragerl@feddit.de 0 points 1 year ago

Can you share the actual error message that you get in Eclipse?

[-] Threen@aussie.zone 0 points 1 year ago

Oh yes, sorry

The error it gives is that the inner bubblePredicate has an Unhandled exception type IOException.

[-] LarsTragerl@feddit.de 1 points 1 year ago

Hm, that's really interesting. I downloaded Eclipse (haven't used it in years, IDEA ftw) and yes I can reproduce it. To me it looks like a compiler bug. From what I understand E should be inferred to RuntimeException, but it obviously is not. Maybe you could try to file a bug report on https://bugs.eclipse.org/

this post was submitted on 12 Jun 2023
2 points (100.0% liked)

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