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 :

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// 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);
    }
}

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Output :

2
4
6
8
10

Example 2 :

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// 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);
    }
}

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Output :

-2147483648
-2147483647
-2147483646
-2147483645
-2147483644

Example 3 :

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// 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);
    }
}

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Output :

0
1
2
3
4


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In love with a semicolon because sometimes i miss it so badly)

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