The pair class in the C++ standard library is used more. We can implement our own user-defined pair class in Java, and its object can be used anywhere like any other parameter.

Note : This class is equivalent to pair<int,int> class in java. You can create your own template or classes for other data types.

Syntax For defining the pair class can be:

class pair{
   int first,second;
   
   // constructor for assigning values
   pair(int first,int second){
       this.first = first;
       this.second = second;
   }
   
   // function which returns a pair
   pair values(){
       return new pair(first,second);
   }
   
   // printing the pair class
   @Override
   public String toString(){
       return "("+first+","+second+")";
   }
}

// Java program to create a pair class
// and initialize an array of that
// pair class object

public class pair_example {
	public static void main(String[] args)
	{
		pair[] arr = new pair[5];
		for (int i = 0; i < 5; i++) {
			arr[i] = new pair(i + 1, i + 2);
		}
	
		// printing an array of pairs easily
		for (pair i : arr) {
			System.out.println(i);
		}
	
		// to extract particular values
		int value = arr[3].second;
		System.out.println("Required Value = " + value);
	}
}

// user defined pair class of integer type
class pair {
	int first, second;

	// constructor for assigning values
	pair(int first, int second)
	{
		this.first = first;
		this.second = second;
	}

	// function which returns a pair
	pair values() { return new pair(first, second); }

	// printing the pair class
	@Override public String toString()
	{
		return first + "," + second;
	}
}

Output

1,2
2,3
3,4
4,5
5,6
Required Value = 5

Implementation Example:

Suppose we'd like to store the ith prime and its index together during a structure.

// Java program to create a struct/pair class
// for storing a prime number with its index

class GFG {
	public static void main(String[] args)
	{
		// first N prime numbers
		int N = 30;

		// creating list of pairs
		java.util.ArrayList p = new java.util.ArrayList<>();
	
		int index = 1;
		for (int i = 1; i <= N; i++) {
			if (isPrime(i)) {
			
				// creating new pair object and appending to
				// list
				p.add(new pair(index++, i));
			}
		}
	
		System.out.println("i and the ith prime numbers are :");
		System.out.println(p);
	}

	// function to check prime
	static boolean isPrime(int n)
	{
		if (n < 2)
			return false;
		for (int i = 2; i * i <= n; i++) {
			if (n % i == 0)
				return false;
		}
		return true;
	}
}

// user defined pair class of integer type
class pair {
	int first, second;

	// constructor for assigning values
	pair(int first, int second)
	{
		this.first = first;
		this.second = second;
	}

	// function which returns a pair
	pair values() { return new pair(first, second); }

	// printing the pair class
	@Override public String toString()
	{
		return "(" + first + "," + second + ")";
	}
}

Output

i and the ith prime numbers are :
[(1,2), (2,3), (3,5), (4,7), (5,11), (6,13), (7,17), (8,19), (9,23), (10,29)]