IntStream mapToLong() in Java

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

Note : IntStream mapToLong() 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 mapToLong(IntToLongFunction 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 a LongStream 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 mapToLong
// (IntToLongFunction 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 an IntStream
        IntStream stream = IntStream.of(2, 4, 6, 8, 10);
  
        // Using LongStream mapToLong(IntToLongFunction mapper)
        // to return a LongStream consisting of the
        // results of applying the given function to
        // the elements of this stream.
        LongStream stream1 = stream.mapToLong(num -> (long)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 mapToLong
// (IntToLongFunction 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 an IntStream
        IntStream stream = IntStream.of(2, 4, 6, 8, 10);
  
        // Using LongStream mapToLong(IntToLongFunction mapper)
        // to return a LongStream consisting of the
        // results of applying the given function to
        // the elements of this stream.
        LongStream stream1 = stream.mapToLong(num -> (long)num + Integer.MAX_VALUE);
  
        // Displaying the elements in stream1
        stream1.forEach(System.out::println);
    }
}

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Output :

2147483649
2147483651
2147483653
2147483655
2147483657

Example 3 :

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// Java code for LongStream mapToLong
// (IntToLongFunction 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 an IntStream
        IntStream stream = IntStream.range(5, 10);
  
        // Using LongStream mapToLong(IntToLongFunction mapper)
        // to return a LongStream consisting of the
        // results of applying the given function to
        // the elements of this stream.
        LongStream stream1 = stream.mapToLong(num -> (long)num - 20);
  
        // Displaying the elements in stream1
        stream1.forEach(System.out::println);
    }
}

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Output :

-15
-14
-13
-12
-11


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

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