Iterators

Iterators framework is the implementation of lazy collections functional based on Iterator and Iterable interfaces. Requires Java 1.5 +

How do I use it?

You can download the latest build at: https://github.com/Megaprog/Iterators/releases

Or use it as a maven dependency:

<dependency>
    <groupId>org.jmmo</groupId>
    <artifactId>iterators</artifactId>
    <version>2.0</version>
</dependency>

What can I do with Iterators?

• Create Empty, Singleton or Optional Iterable
• Merge two or more iterators into one
• Filter iterator values
• Map iterator values
• Reduce iterator values to produce a single result
• Repeat a value by creation iterator contains this value some number of times
• Produce ranges contains the sequence of integer or double values
• Create Java Collection, List or Set from any Iterable

Examples

Obtain empty Iterable:

Iterable<String> empty = Iterators.<String>empty();

Obtain Iterable contains a single element:

Iterable<String> singleton = Iterators.singleton("jmmo");

Create iterator contains repeated value some number of times (will contains 1, 1, 1, 1, 1):

Iterable<Integer> repeat = Iterators.repeat(1, 5);

Create iterator contains the range of integer or double values (will contains 1, 2, 3):

Iterable<Integer> range = Iterators.range(1, 3);

Merge two Iterable's in one (will contains 1, 2, 4, 5):

Iterable<Integer> merged = Iterators.merge(Arrays.asList(1, 2), Arrays.asList(4, 5));

Make the flat Iterable from an Iterable of Iterable's (will contains 1, 2, 0, 3, 4):

Iterable<Integer> flat = Iterators.flat(Arrays.asList(Iterators.range(1, 2), Iterators.singleton(0), Iterators.range(3, 4)));

Filter the Iterable (will contains even numbers from 2 to 100):

Iterable<Integer> even = Iterators.filter(Iterators.range(1, 100), new Filter<Integer>() {
    @Override
    public boolean test(Integer integer) {
        return integer % 2 == 0;
    }
});

Map the Iterable (will contains "1", "2", "3"):

Iterable<String> int2String = Iterators.map(Iterators.range(1, 3), new Mapper<Integer, String>() {
    @Override
    public String mapper(Integer integer) {
        return Integer.toString(integer);
    }
});

Reduce Iterable to produce a single result (will be 6):

Reducer<Integer> reducer = new Reducer<Integer>() {
    @Override
    public Integer accumulate(Integer previous, Integer current) {
        return previous + current;
    }
};

Mapper<String, Integer> mapper = new Mapper<String, Integer>() {
    @Override
    public Integer mapper(String s) {
        return s.length();
    }
};

int length = reducer.reduce(0, mapper.map("AB", "C", "DEF", ""));

Create Collection, List or Set from any Iterable:

Collection<Integer> rangeCollection = Iterators.toCollection(Iterators.range(1, 3), new Vector<Integer>());
List<Integer> rangeList = Iterators.toList(Iterators.range(1, 3));
Set<Integer> rangeSet = Iterators.toSet(Iterators.range(1, 3));