A Pair is a Tuple from JavaTuples library that deals with 2 elements. Since this Pair is a generic class, it can hold any type of value in it.

Since Pair is a Tuple, hence it also has all the characterstics of JavaTuples:

• They are Typesafe
• They are Immutable
• They are Iterable
• They are Serializable
• They are Comparable (implements Comparable<Tuple>)
• They implement equals() and hashCode()
• They also implement toString()

Class Declaration

public final class Pair<A, B> extends Tuple 
           implements IValue0<A>, IValue1<B;>

Class hierarchy

Object
  ↳ org.javatuples.Tuple
      ↳ org.javatuples.Pair<A, B>

Creating Pair Tuple

• From Constructor:

  Syntax:

  Pair<A, B> pair = new Pair<A, B>(value1, value2);
  

  Example:

  filter_none

  edit
  close

  play_arrow

  link
  brightness_4
  code

  // Below is a Java program to create // a Pair tuple from Constructor    import java.util.*; import org.javatuples.Pair;    class GfG {     public static void main(String[] args)     {         Pair<Integer, String> pair             = new Pair<Integer, String>(Integer.valueOf(1), "GeeksforGeeks");            System.out.println(pair);     } }

  chevron_right

  filter_none

  Output:

  
  
  
  

  [1, GeeksforGeeks]
  

• Using with() method: The with() method is a function provided by the JavaTuples library, to instantiate the object with such values.

  Syntax:

  Pair<type1, type2> pair = Pair.with(value1, value2);
  

  Example:

  filter_none

  edit
  close

  play_arrow

  link
  brightness_4
  code

  // Below is a Java program to create // a Pair tuple from with() method    import java.util.*; import org.javatuples.Pair;    class GfG {     public static void main(String[] args)     {         Pair<Integer, String> pair             = Pair.with(Integer.valueOf(1), "GeeksforGeeks");            System.out.println(pair);     } }

  chevron_right

  filter_none

  Output:

  [1, GeeksforGeeks]
  

• From other collections: The fromCollection() method is used to create a Tuple from a collection, and fromArray() method is used to create from an array. The collection/array must have the same type as of the Tuple and the number of values in the collection/array must match the Tuple class.

  Syntax:

  Pair<type1, type2> pair = Pair.fromCollection(collectionWith_2_value);
  Pair<type1, type2> pair = Pair.fromArray(arrayWith_2_value);
  

  Example:

  filter_none

  edit
  close

  play_arrow

  link
  brightness_4
  code

  // Below is a Java program to create // a Pair tuple from Collection    import java.util.*; import org.javatuples.Pair;    class GfG {     public static void main(String[] args)     {         // Creating Pair from List         List<String> list = new ArrayList<String>();         list.add("GeeksforGeeks");         list.add("A computer portal");         Pair<Strin, String> pair             = Pair.fromCollection(list);            // Creating Pair from Array         String[] arr = { "GeeksforGeeks", "A computer portal" };         Pair<String, String> otherPair             = Pair.fromArray(arr);            System.out.println(pair);         System.out.println(otherPair);     } }

  chevron_right

  filter_none

  Output:

  [GeeksforGeeks, A computer portal]
  [GeeksforGeeks, A computer portal]
  

Getting Value

The getValueX() method can be used to fetch the value in a Tuple at index X. The indexing in Tuples start with 0. Hence the value at index X represents the value at position X+1.

Syntax:

Pair<type1, type2> pair = 
    new Pair<type1, type2>(value1, value2);

type1 val1 = pair.getValue0();

Example:

Output:

1

Setting Pair Value

Since the Tuples are immutable, it means that modifying a value at an index is not possible. Hence, JavaTuples offer setAtX(value) which creates a copy of the Tuple with a new value at index X, and returns that Tuple.

Syntax:

Pair<type1, type2> pair = 
    new Pair<type1, type2>(value1, value2);

type1 val1 = pair.getValue0();

Example:

Output:

[1, A computer portal]

Adding a Value

Adding a value can be done with the help of addAtX() method, where X represents the index at which the value is to be added. This method returns a Tuple of element one more than the called Tuple.

Syntax:

Pair<type1, type2> pair = 
    new Pair<type1, type2>(value1, value2);

Triplet<type 1, type 2, type 3> pair = 
    pair.addAt2(value 2);

Example:

Output:

[1, GeeksforGeeks, A computer portal]

Searching in Pair

An element can be searched in a tuple with the pre-defined method contains(). It returns a boolean value whether the value is present or not.

Syntax:

Pair<type1, type2> pair = 
    new Pair<type1, type2>(value1, value2);

boolean res = pair.contains(value2);

Example:

Output:

true
false

Iterating through Pair

Since Pair implement the Iterable<Object> interface. It means that they can be iterated in the same way as collections or arrays.

Syntax:

Pair<type1, type2> pair = 
    new Pair<type1, type2>(value1, value2);

for (Object item : pair) {
        ...
}

Example:

Output:

1
GeeksforGeeks

Attention reader! Don’t stop learning now. Get hold of all the important Java Foundation and Collections concepts with the Fundamentals of Java and Java Collections Course at a student-friendly price and become industry ready.