What is the IntStream.mapToObj method in Java?

Overview

In Java, the mapToObj() method of the IntStream interface is used to return an object-valued stream. This stream has the results obtained by applying the implementation of the IntFunction functional interface.

Note: mapToObj() is an intermediate operation. This operation is performed on a stream instance and results in a stream instance.

Syntax

<U> Stream<U> mapToObj(IntFunction<? extends U> mapper);

Parameters

  • IntFunction<? extends U> mapper: This is the implementation of the IntFunction interface.

Return value

This method returns a new object-valued stream.

Example

import java.util.stream.Stream;
import java.util.stream.IntStream;
class Main {
    public static void main(String[] args)
    {
        IntStream stream = IntStream.rangeClosed(2, 7);
        Stream<Integer> integerStream = stream.mapToObj(Integer::bitCount);
        integerStream.forEach(System.out::println);
    }
}

Explanation

  • Lines 1–2: We import the relevant packages.
  • Line 7: We use the rangeClosed() method to create an IntStream.
  • Line 9: We use the mapToObj(IntFunction mapper) of the IntStream interface to create a new stream called integerStream, which stores the number of set bits of each integer in the stream.
  • Line 11: We print integerStream.
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