Checked-Exceptions-enabled Java 8+ Functional Interfaces

and adapters

Rationale

Standard java.util.function Functional Interfaces aren't checked-exception-friendly due to the absence of throws ... clause which results in tedious and verbose necessity of handling them by adding try-catch boilerplate.

Which makes one-liners like this:

path -> new URI(path)

become as verbose as:

path -> {
    try {
        return new URI(path);
    } catch (URISyntaxException e) {
        throw new RuntimeException(e);
    }
}

By applying com.pivovarit.function functional interfaces, it's possible to regain clarity and readability:

ThrowingFunction<String, URI, URISyntaxException> toUri = URI::new;

and use them seamlessly with native java.util.function classes by using custom ThrowingFunction#unchecked adapters:

...stream()
  .map(unchecked(URI::new)) // static import of ThrowingFunction#unchecked
  .forEach(System.out::println);

which avoids ending up with:

 ...stream().map(path -> {
     try {
         return new URI(path);
     } catch (URISyntaxException e) {
         throw new RuntimeException(e);
     }}).forEach(System.out::println);

Basic API

Functional Interfaces

• ThrowingFunction
• ThrowingIntFunction
• ThrowingToLongFunction
• ThrowingBiConsumer
• ThrowingBiFunction
• ThrowingBiPredicate
• ThrowingBinaryOperator
• ThrowingConsumer
• ThrowingPredicate
• ThrowingRunnable
• ThrowingSupplier
• ThrowingUnaryOperator

Adapters

• static Function<T, R> unchecked(ThrowingFunction<> f) {...}

Transforms a ThrowingFunction instance into a standard java.util.function.Function by wrapping checked exceptions in a RuntimeException and rethrowing them.

• static Function<T, Optional<R>> lifted() {...}

Transforms a ThrowingFunction instance into a regular Function returning result wrapped in an Optional instance.

• default ThrowingFunction<T, Void, E> asFunction() {...}

Returns Throwing(Predicate|Supplier|Consumer) instance as a new ThrowingFunction instance.

Maven Central

<dependency>
    <groupId>com.pivovarit</groupId>
    <artifactId>throwing-function</artifactId>
    <version>1.5.1</version>
</dependency>

Gradle

compile 'com.pivovarit:throwing-function:1.5.1'

Dependencies

None - the library is implemented using core Java libraries.

Version history

1.5.1 (06-05-2020)

• Fixed visibility issues with ThrowingIntFunction

1.5.0 (26-01-2019)

• Introduced proper Semantic Versioning
• Introduced ThrowingIntFunction
• Moved interfaces to com.pivovarit.function
• Removed controversial unwrap() functionality