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Project architect: @victornoel

ATTENTION: We're still in a very early alpha version, the API may and will change frequently. Please, use it at your own risk, until we release version 1.0. You can view our progress towards this release here.

Cactoos is a collection of object-oriented Java primitives.

Motivation. We are not happy with JDK, Guava, and Apache Commons because they are procedural and not object-oriented. They do their job, but mostly through static methods. Cactoos is suggesting to do almost exactly the same, but through objects.

Principles. These are the design principles behind Cactoos.

How to use. The library has no dependencies. All you need is this (get the latest version here):




dependencies {
  compile 'org.cactoos:cactoos::0.55.0

Java version required: 1.8+.

StackOverflow tag is cactoos.


More about it here: Object-Oriented Declarative Input/Output in Cactoos.

To read a text file in UTF-8:

String text = new TextOf(
  new File("/code/a.txt")

To write a text into a file:

new LengthOf(
  new TeeInput(
    "Hello, world!",
    new File("/code/a.txt")

To read a binary file from classpath:

byte[] data = new BytesOf(
  new ResourceOf("foo/img.jpg")


To format a text:

String text = new FormattedText(
  "How are you, %s?",

To manipulate with a text:

// To lower case
new Lowered(
	new TextOf("Hello")
// To upper case
new Upper(
	new TextOf("Hello")


More about it here: Lazy Loading and Caching via Sticky Cactoos Primitives.

To filter a collection:

Collection<String> filtered = new ListOf<>(
  new Filtered<>(
    s -> s.length() > 4,
    new IterableOf<>("hello", "world", "dude")

To flatten one iterable:

new Joined<>(
  new Mapped<IterableOf>(
    iter -> new IterableOf<>(
      new ListOf<>(iter).toArray(new Integer[]{})
    new IterableOf<>(1, 2, 3, 4, 5, 6)
);    // Iterable<Integer>

To flatten and join several iterables:

new Joined<>(
  new Mapped<IterableOf>(
    iter -> new IterableOf<>(
      new Joined<>(iter)
    new Joined<>(
      new IterableOf<>(new IterableOf<>(1, 2, 3)),
      new IterableOf<>(new IterableOf<>(4, 5, 6))
);    // Iterable<Integer>

To iterate a collection:

new And(
  new Mapped<>(
    new FuncOf<>(
      input -> {
        System.out.printf("Item: %s\n", input);
      new True()
    new IterableOf<>("how", "are", "you", "?")

Or even more compact:

new ForEach<String>(
    input -> System.out.printf(
        "Item: %s\n", input
).exec(new IterableOf("how", "are", "you", "?"));

To sort a list of words in the file:

List<Text> sorted = new ListOf<>(
  new Sorted<>(
    new Mapped<>(
      text -> new ComparableText(text),
      new Split(
        new TextOf(
          new File("/tmp/names.txt")
        new TextOf("\\s+")

To count elements in an iterable:

int total = new LengthOf(
  new IterableOf<>("how", "are", "you")

To create a set of elements by providing variable arguments:

final Set<String> unique = new SetOf<String>(

To create a set of elements from existing iterable:

final Set<String> words = new SetOf<>(
    new IterableOf<>("abc", "bcd", "abc", "ccc")

To create a sorted iterable with unique elements from existing iterable:

final Iterable<String> sorted = new Sorted<>(
    new SetOf<>(
        new IterableOf<>("abc", "bcd", "abc", "ccc")

To create a sorted set from existing vararg elements using comparator:

final Set<String> sorted = new org.cactoos.set.Sorted<>(
    (first, second) -> first.compareTo(second),
    "abc", "bcd", "abc", "ccc", "acd"

To create a sorted set from existing iterable using comparator:

final Set<String> sorted = new org.cactoos.set.Sorted<>(
    (first, second) -> first.compareTo(second),
    new IterableOf<>("abc", "bcd", "abc", "ccc", "acd")

Funcs and Procs

This is a traditional foreach loop:

for (String name : names) {
  System.out.printf("Hello, %s!\n", name);

This is its object-oriented alternative (no streams!):

new And(
  n -> {
    System.out.printf("Hello, %s!\n", n);
    return new True().value();

This is an endless while/do loop:

while (!ready) {
  System.out.println("Still waiting...");

Here is its object-oriented alternative:

new And(
  ready -> {
    System.out.println("Still waiting...");
    return !ready;
  new Endless<>(booleanParameter)

Dates and Times

From our org.cactoos.time package.

Our classes are divided in two groups: those that parse strings into date/time objects, and those that format those objects into strings.

For example, this is the traditional way of parsing a string into an OffsetDateTime:

final OffsetDateTime date = OffsetDateTime.parse("2007-12-03T10:15:30+01:00");

Here is its object-oriented alternative (no static method calls!) using OffsetDateTimeOf, which is a Scalar:

final OffsetDateTime date = new OffsetDateTimeOf("2007-12-03T10:15:30+01:00").value();

To format an OffsetDateTime into a Text:

final OffsetDateTime date = ...;
final String text = new TextOfDateTime(date).asString();

Our objects vs. their static methods

Cactoos Guava Apache Commons JDK 8
And Iterables.all() - -
Filtered Iterables.filter() ? -
FormattedText - - String.format()
IsBlank - StringUtils.isBlank() -
Joined - - String.join()
LengthOf - - String#length()
Lowered - - String#toLowerCase()
Normalized - StringUtils.normalize() -
Or Iterables.any() - -
Repeated - StringUtils.repeat() -
Replaced - - String#replace()
Reversed - - StringBuilder#reverse()
Rotated - StringUtils.rotate() -
Split - - String#split()
StickyList Lists.newArrayList() ? Arrays.asList()
Sub - - String#substring()
SwappedCase - StringUtils.swapCase() -
TextOf ? IOUtils.toString() -
TrimmedLeft - StringUtils.stripStart() -
TrimmedRight - StringUtils.stripEnd() -
Trimmed - StringUtils.stripAll() String#trim()
Upper - - String#toUpperCase()


Ask your questions related to cactoos library on Stackoverflow with cactoos tag.

How to contribute?

Just fork the repo and send us a pull request.

Make sure your branch builds without any warnings/issues:

mvn clean verify -Pqulice

To run a build similar to the CI with Docker only, use:

docker run \
	--tty \
	--interactive \
	--workdir=/main \
	--volume=${PWD}:/main \
	--volume=cactoos-mvn-cache:/root/.m2 \
	--rm \
	maven:3-jdk-8 \
	bash -c "mvn clean install site -Pqulice -Psite --errors; chown -R $(id -u):$(id -g) target/"

To remove the cache used by Docker-based build:

docker volume rm cactoos-mvn-cache

Note: Checkstyle is used as a static code analyze tool with checks list in GitHub precommits.