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Pair Class in JavaTuples

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  • Difficulty Level : Easy
  • Last Updated : 05 Aug, 2021
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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 characteristics 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

Java




// 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);
    }
}

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

Java




// 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);
    }
}

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

Java




// 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);
    }
}

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:  

Java




// Below is a Java program to get
// a Pair value
 
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.getValue0());
    }
}

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:  

Java




// Below is a Java program to set
// a Pair value
 
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");
 
        Pair<Integer, String> otherPair
            = pair.setAt1("A computer portal");
 
        System.out.println(otherPair);
    }
}

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:  

Java




// Below is a Java program to add
// a value
 
import java.util.*;
import org.javatuples.Pair;
import org.javatuples.Triplet;
 
class GfG {
    public static void main(String[] args)
    {
        Pair<Integer, String> pair
            = Pair.with(Integer.valueOf(1), "GeeksforGeeks");
 
        Triplet<Integer, String, String> triplet
            = pair.addAt2("A computer portal");
 
        System.out.println(triplet);
    }
}

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:  

Java




// Below is a Java program to search
// a value
 
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");
 
        boolean exist = pair.contains("GeeksforGeeks");
        boolean exist1 = pair.contains(4);
 
        System.out.println(exist);
        System.out.println(exist1);
    }
}

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

Java




// Below is a Java program to iterate
// a Pair
 
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");
 
        for (Object item : pair)
            System.out.println(item);
    }
}

Output: 

1
GeeksforGeeks

 


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