jTuples

Java gets a pair.

Have you ever wanted a pair? Do you end up writing C-like structs every other project? Fear not.

The jTuples project provides tuple implementations for the Java platform. With jTuples, you can group up to ten (!) objects at once (although not recommended).

If you are into functional programming, know that jTuples treats functions as first-class citizens. It provides some utilities to combine functions too!

Requires JDK 8 or higher.

Installation

You can use Maven to build jTuples and install it into your Maven repository with the following command:

mvn install

If you do not use Maven to manage your project build, you can build a .jar file with the following command:

mvn package

The .jar will be placed in the "target" directory.

Usage

You can create a Pair in one of two ways:

1. With the constructor:

Pair<String, String> pair = new Pair<>("hello", "world");

2. With Tuples.with factory method:

Pair<String, String> pair = Tuples.with("hello", "world");

The Tuples class also has factory methods for other tuples.

All tuples are immutable. To easily change a member of a tuple, you can use one of the apply* methods to create a new tuple by applying a function:

Pair<String, String> pair = new Pair<>("hello", "world");
Pair<String, String> other = pair.applySecond(s -> s.toUpperCase());
// => ("hello", "WORLD")

You can also change the order of the elements of the tuples. You can flip it around:

Pair<String, String> pair = new Pair<>("hello", "world");
Pair<String, String> other = pair.invert();
// => ("world", "hello")

If the types do not match, shift the elements to the left, or to the right:

Triple<String, Integer, Double> triple = new Triple<>("one", 1, 1.0);
Triple<Integer, Double, String> toTheLeft = triple.shiftLeft();
// => (1, 1.0, "one")
Triple<Double, String, Integer> toTheRight = triple.shiftRight();
// => (1.0, "one", 1)

Integrate with existing code, converting to lists or arrays:

Pair<String, String> pair = new Pair<>("hello", "world");
Object[] array = pair.toArray();
// => ["hello", "world"]
List<?> list = pair.asList();
// => ["hello", "world"]

Speaking of lists, zip two lists together:

List<Integer> integers = Arrays.asList(1, 2, 3);
List<String> strings = Arrays.asList("one", "two", "three");
List<Pair<Integer, String>> pairs = Tuples.zip(integers, strings);
// => [(1, "one"), (2, "two"), (3, "three")]

Documentation

The javadocs can be seen here.