IntStream generate() Method in Java

In Java, the IntStream.generate() method is part of the java.util.stream.IntStream class. This method is used to generate an infinite sequential and unordered stream of int values. This method takes IntSupplier as an argument.

Note: It is commonly used for generating random numbers, constant streams, or any kind of data where we need a sequence of numbers that follows a particular pattern.

Declaration of IntStream generate() Method

static IntStream generate(IntSupplier s)

• Parameter: This method takes a single parameter, IntSupplier, it is a functional interface that represents a supplier of int values. The getAsInt() method of this interface generates an int value when it is called.
• Return Type: This method returns a new infinite, sequential, unordered IntStream. This stream is created by repeatedly getting values from the IntSupplier.

Note: IntStream is the type of stream that will hold primitive int values.

How generate() Method Works?

The generate() method keeps on calling the IntSupplier getAsInt() method to create a new int each time. It will keep on generating values unless we set a limit. This method is useful when we need to generate random numbers and endless sequences or repeating patterns.

Now, we are going to discuss some examples, for better understanding.

Examples of Java IntStream generate() Method

Example 1: In this example, we will generate a stream of random number.

// Java program for IntStream.generate()
// to generate an infinite sequential
// unordered IntStream
import java.util.*;
import java.util.stream.IntStream;

class Geeks {

    // Driver code
    public static void main(String[] args) {
        
        // Using IntStream.generate() method 
        // to generate 7 random integers
        IntStream s = IntStream.generate(() -> (int)(Math.random() * 10000));

        // Displaying the randomly generated values
        s.limit(7).forEach(System.out::println);
    }
}

2805
4606
6570
2748
6968
2772
5052

Explanation: Here, we are using IntStream.generate(() -> (int)(Math.random() * 10000), it will create an infinite stream of random integer. Each number is generated by picking a random decimal between 0 and 1 and then multiply by 10,000, which gives a number between 0 and 999. We are using stream.limit(7) so that we can take only the 7 number as the stream is infinite that's why we are setting the limit, if we do not set the limit the program will run forever and then we are printing all the seven random number one by one.

Example 2: In this example, we will generate a stream of constant values.

// Java program for IntStream.generate()
// to generate an infinite sequential
// unordered IntStream of constant values
import java.util.*;
import java.util.stream.IntStream;

class Geeks {

    // Driver code
    public static void main(String[] args) {
        
        // Using IntStream.generate() method to 
        // generate a stream of constant values (5)
        IntStream s = IntStream.generate(() -> 5);

        // Displaying the first 10 values 
        // of the constant stream
        s.limit(10).forEach(System.out::println);
    }
}

5
5
5
5
5
5
5
5
5
5

Explanation: Here, we are using IntStream.generate(() -> 5), it will create a stream where every element is the constant value 5. The lambda expression () -> 5 will return the number 5 each time. We are using stream.limit(10), this will limits the stream just to 10 elements, if we do not set the limit then the program will keep on generating the number 5 infinitely and then we are printing the number 5, ten times.