README.md

Lightweight-Stream-API

Stream API from Java 8 rewrited on iterators for Java 7 and below.

Includes

• Functional interfaces (Supplier, Function, Consumer etc);
• Stream (without parallel processing but with custom operators);
• Optional class;
• Exceptional class - functional way to deal with exceptions;
• Objects from Java 7.

Usage

Stream.of(/* array | list | set | map | anything based on Iterator/Iterable interface */)
    .filter(..)
    .map(..)
    ...
    .sorted()
    .forEach(..);
Stream.of(value1, value2, value3)...
Stream.range(0, 10)...

Example project: https://github.com/aNNiMON/Android-Java-8-Stream-Example

Custom operators

Unlike Java 8 streams, Lightweight-Stream-API provides an ability to apply custom operators.

Stream.of(...)
    .custom(new Reverse<>())
    .forEach(...);

public final class Reverse<T> implements UnaryOperator<Stream<T>> {

    @Override
    public Stream<T> apply(Stream<T> stream) {
        final Iterator<? extends T> iterator = stream.getIterator();
        final ArrayDeque<T> deque = new ArrayDeque<T>();
        while (iterator.hasNext()) {
            deque.addFirst(iterator.next());
        }
        return Stream.of(deque.iterator());
    }
}

More examples you can find here.

Download

Download latest release or grab via Maven:

<dependency>
  <groupId>com.annimon</groupId>
  <artifactId>stream</artifactId>
  <version>1.0.7</version>
</dependency>

or Gradle:

dependencies {
  ...
  compile 'com.annimon:stream:1.0.7'
  ...
}

Also included version for Java ME. Checkout javame branch.

For use lambda expressions in Java 6, Java 7 or Android, take look at Retrolambda repository.