import java.util.ArrayList; import java.util.Collection; import java.util.List; /** * Tuple is a readonly data structure. Just after initialization, it * remains in the same state after initialization and so no value can be added, * removed or changed. Quite useful to use when you require * methods that return multiple values since Tuple provides a trivial constructor * for variable argument initialization. For example, if i have three Es * E1, E2 and E3 and you need to return them once, you will just * do: * return new Tuple(E1, E2, E3) . */ public class Tuple{ private List values = new ArrayList<>(); /** * Initialize an empty Tuple of E. * Note: It will remain in this state till it is garbage collected. */ public Tuple() { } /** * Initialize tuple of a single E. * @param value E. Value to initialize a Tuple E. */ public Tuple(E value) { values.add(value); } /** * Initialize tuple with variable amount f arguments. * @param values Tuple values. */ public Tuple(E... values) { for (E val : values) { this.values.add(val); } } public Tuple(List values){ this.values.addAll(values); } /** * Get a copy of this Tuple E. * @return Tuple */ public Tuple copy() { return new Tuple(values); } public static void main(String [] args){ Tuple tuple = new Tuple<>(3.6, 5.6, 2.1, 3.9, 7.1); System.out.println("See the power of our Tuple object. You can use it to return multiple values since it's trivial to initialize with values.\n"); System.out.println(tuple); System.out.println(new Tuple("E1", "E2", "E3")); System.out.println(new Tuple(new Tuple("E1", "E2", "E3"), tuple)); System.out.println(new Tuple(new Tuple("E1", "E2", "E3").asList(), tuple.asList())); } /** * Get values of this Tuple E as a List. * @return List */ public List asList() { List values = new ArrayList<>(); values.addAll(this.values); return values; } /** * Get values of this Tuple in an array E. * @return Array */ public Object[] toArray() { return values.toArray(); } /** * Get number of elements of this Tuple E.. * @return int */ public int size() { return values.size(); } /** * Get an item from the specified index in this Tuple E. * @param index int starting at 0. * @return E */ public E getItem(int index) { return values.get(index); } @Override public String toString() { return "Tuple" + values.toString().replace("[", "(").replace("]", ")"); } @Override /** * Checks whether the argument Tuple E has exactly the same values * at the same position with this Tuple E. */ public boolean equals(Object other) { try { Tuple tup = (Tuple) other; return tup.values.equals(values); } catch (ClassCastException e) { return false; } } @Override public int hashCode() { return values.hashCode(); } }

Tuple in Java