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

Includes:

• Functional interfaces;
• Stream (without parallel processing);
• Optional class;
• Objects from Java 7.

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

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

Download latest release or grab via Maven:

<dependency>
  <groupId>com.annimon</groupId>
  <artifactId>stream</artifactId>
  <version>1.0.2</version>
</dependency>`

or Gradle:

dependencies {
  ...
  compile 'com.annimon:stream:1.0.2'
  ...
}

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.