Stuff4J is whatever code I currently find most useful for building Java apps, that is not already available without fuss in Commons Lang, Guava, JOOL, et cetera.

Most of it is geared toward reducing the awful boilerplate that arises from checked exceptions. The latter are now more or less regarded as a failure. With proper use of generics and lambdas we can eliminate most of them from an application, without providing an extensive library to mirror every method that throws.

Merge lines from multiple files:

paths.stream()
        .flatMap(path -> Unchecked.apply(Files::readAllLines, path).stream())
        .collect(toList());

Adapt a ResultSet to consumers that don't handle SQLException:

Function<String,Object> columnGetter = Unchecked.function(col -> resultSet.getObject(col));

Monadic exception handling a la Fugue, Vavr:

Try.to(() -> someThrowingFunction())
    .map(result -> anotherThrowingFunction(result))
    .onFailure(e -> myLog.error("Operation failed", e))
    .orElse(() -> alternateResult);

Stuff4J also has some helpful utility types like tuples. Specify multi-valued function outputs without custom classes:

return Pair.of("foo", 2);
return Trio.of("foo", 2, 1.0);

Feel free to use. MIT-licensed, no runtime dependencies apart from Java 9.

Classes in the .tbd package are prototypes and subject to rapid, non-backward-compatible change.