LongStream mapToInt() in Java with Examples

LongStream mapToInt() returns an IntStream consisting of the results of applying the given function to the elements of this stream.

Note : LongStream mapToInt() is a intermediate operation. These operations are always lazy. Intermediate operations are invoked on a Stream instance and after they finish their processing, they give a Stream instance as output.
Syntax :

LongStream mapToInt(LongToIntFunction mapper)

Parameters :

1. LongStream : A sequence of primitive long-valued elements. This is the long primitive specialization of Stream.
2. mapper : A stateless function to apply to each element.

Return Value : The function returns an IntStream consisting of the results of applying the given function to the elements of this stream.

Example 1 :

// Java code for LongStream mapToInt
// (LongToIntFunction mapper)
import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.LongStream;

class GFG {

    // Driver code
    public static void main(String[] args)
    {
        // Creating a LongStream
        LongStream stream = LongStream.of(2L, 4L, 6L, 8L, 10L);

        // Using LongStream mapToInt(LongToIntFunction mapper)
        // to return an IntStream consisting of the
        // results of applying the given function to
        // the elements of this stream.
        IntStream stream1 = stream.mapToInt(num -> (int) num);

        // Displaying the elements in stream1
        stream1.forEach(System.out::println);
    }
}

Output :

2
4
6
8
10

Example 2 :

// Java code for LongStream mapToInt
// (LongToIntFunction mapper)
import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.LongStream;

class GFG {

    // Driver code
    public static void main(String[] args)
    {
        // Creating a LongStream
        LongStream stream = LongStream.of(1L, 2L, 3L, 4L, 5L);

        // Using LongStream mapToInt(LongToIntFunction mapper)
        // to return an IntStream consisting of the
        // results of applying the given function to
        // the elements of this stream.
        IntStream stream1 = stream.mapToInt(num ->
                                   (int) num + Integer.MAX_VALUE);

        // Displaying the elements in stream1
        stream1.forEach(System.out::println);
    }
}

Output :

-2147483648
-2147483647
-2147483646
-2147483645
-2147483644

Example 3 :

// Java code for LongStream mapToInt
// (LongToIntFunction mapper)
import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.LongStream;

class GFG {

    // Driver code
    public static void main(String[] args)
    {
        // Creating a LongStream
        LongStream stream = LongStream.range(2L, 7L);

        // Using LongStream mapToInt(LongToIntFunction mapper)
        // to return an IntStream consisting of the
        // results of applying the given function to
        // the elements of this stream.
        IntStream stream1 = stream.mapToInt(num ->
                                    (int) num - 2);

        // Displaying the elements in stream1
        stream1.forEach(System.out::println);
    }
}

Output :

0
1
2
3
4