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Pair Class in Java

Last Updated : 25 Apr, 2023
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In C++, we have std::pair in the utility library which is of immense use if we want to keep a pair of values together. We were looking for an equivalent class for pair in Java but Pair class did not come into existence till Java 7. JavaFX 2.2 has the javafx.util.Pair class which can be used to store a pair. We need to store the values into Pair using the parameterized constructor provided by the javafx.util.Pair class.  

Note: Note that the <Key, Value> pair is used in HashMap/TreeMap. Here, <Key, Value> simply refers to a pair of values that are stored together.   

Methods provided by the javafx.util.Pair class

Syntax: The pair class in the Java method

Pair<Key Type, Value Type> var_name = new Pair<>(key, value);
  • Pair (K key, V value): Creates a new pair.
  • boolean equals(): It is used to compare two pairs of objects. It does a deep comparison, i.e., it compares on the basis of the values (<Key, Value>) which are stored in the pair objects.   



Pair p1 = new Pair(3, 4);
Pair p2 = new Pair(3, 4);
Pair p3 = new Pair(4, 4);
System.out.println(p1.equals(p2) + “ ” + p2.equals(p3));


true false
  • String toString(): This method will return the String representation of the Pair.
  • K getKey(): It returns the key for the pair.
  • V getValue(): It returns a value for the pair.
  • int hashCode(): Generate a hash code for the Pair.

Accessing values: Using getKey() and getValue() methods we can access a Pair object’s values.

   1. getKey(): gets the first value.
   2. getValue(): gets the second value

Note: Here, <Key, Value> refers to a pair of values that are stored together. It is not like <Key, Value> pair which is used in Map.



// Java program to implement in-built pair classes
import javafx.util.Pair;
class GFG {
    // Main driver method
    public static void main(String[] args)
        Pair<Integer, String> p
            = new Pair<Integer, String>(10, "Hello Geeks!");
        // printing the values of key and value pair
        // separately
        System.out.println("The First value is :"
                           + p.getKey());
        System.out.println("The Second value is :"
                           + p.getValue());

Let us have a look at the following problem.

Problem Statement: We are given the names of n students with their corresponding scores obtained in a quiz. We need to find the student with the maximum score in the class.

Note: You need to have Java 8 installed on your machine in order to run the below program.


// Java program to find a Pair which has maximum score
// Importing required classes
import java.util.ArrayList;
import javafx.util.Pair;
// class
class Test {
    // This method returns a Pair which hasmaximum score
    public static Pair<String, Integer>
    getMaximum(ArrayList<Pair<String, Integer> > l)
        // Assign minimum value initially
        int max = Integer.MIN_VALUE;
        // Pair to store the maximum marks of a
        // student with its name
        Pair<String, Integer> ans
            = new Pair<String, Integer>("", 0);
        // Using for each loop to iterate array of
        // Pair Objects
        for (Pair<String, Integer> temp : l) {
            // Get the score of Student
            int val = temp.getValue();
            // Check if it is greater than the previous
            // maximum marks
            if (val > max) {
                max = val; // update maximum
                ans = temp; // update the Pair
        return ans;
    // Driver method to test above method
    public static void main(String[] args)
        int n = 5; // Number of Students
        // Create an Array List
        ArrayList<Pair<String, Integer> > l
            = new ArrayList<Pair<String, Integer> >();
        /* Create pair of name of student with their
            corresponding score and insert into the
            Arraylist */
        l.add(new Pair<String, Integer>("Student A", 90));
        l.add(new Pair<String, Integer>("Student B", 54));
        l.add(new Pair<String, Integer>("Student C", 99));
        l.add(new Pair<String, Integer>("Student D", 88));
        l.add(new Pair<String, Integer>("Student E", 89));
        // get the Pair which has maximum value
        Pair<String, Integer> ans = getMaximum(l);
        System.out.println(ans.getKey() + " is top scorer "
                           + "with score of "
                           + ans.getValue());


Student C is top scorer with score of 99

Note: The above program might not run in an online IDE, please use an offline compiler.

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