Checked-Exceptions-enabled Java 8+ Functional Interfaces

Overview

Java’s standard java.util.function interfaces are not compatible with checked exceptions. This leads to verbose and cluttered code, requiring manual try-catch blocks for exception handling, 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);
    }
}

This library introduces checked-exception-enabled functional interfaces, like ThrowingFunction, allowing cleaner, more concise code. You can now handle exceptions in functional pipelines without sacrificing readability:

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

Using the ThrowingFunction#unchecked adapter, this can be seamlessly integrated into standard streams:

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

This eliminates the need for bulky try-catch blocks within stream operations:

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

Key Features

• Functional Interfaces: Supports various functional types with checked exceptions.
• Adapters: Provides utility methods to convert Throwing* types into standard Java functional interfaces.
• Lightweight: No external dependencies, implemented using core Java libraries.

Core 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>1.6.1</version>
</dependency>

Gradle

compile 'com.pivovarit:throwing-function:1.6.1'

Dependencies

None - the library is implemented using core Java libraries.

Version history

1.6.1 (25-09-2024)

• Explicit module configuration via a multi-release jar
• Improved Javadoc

1.6.0 (24-09-2024)

• Added Automatic-Module-Name to MANIFEST

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