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DoubleStream mapToInt() in Java

  • Last Updated : 06 Dec, 2018

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

Note : DoubleStream 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 :

IntStream mapToInt(DoubleToIntFunction mapper)

Parameters :

  1. IntStream : A sequence of primitive int-valued elements. This is the int 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 IntStream mapToInt
// (DoubleToIntFunction mapper)
import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.DoubleStream;
  
class GFG {
  
    // Driver code
    public static void main(String[] args)
    {
        // Creating a DoubleStream
        DoubleStream stream = DoubleStream.of(2.3, 4.5, 6.4,
                                              8.7, 10.4);
  
        // Using IntStream mapToInt(DoubleToIntFunction 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 IntStream mapToInt
// (DoubleToIntFunction mapper)
import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.DoubleStream;
  
class GFG {
  
    // Driver code
    public static void main(String[] args)
    {
        // Creating a DoubleStream
        DoubleStream stream = DoubleStream.of(2.3, 4.5, 6.4,
                                              8.7, 10.4);
  
        // Using IntStream mapToInt(DoubleToIntFunction 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 - 10000);
  
        // Displaying the elements in stream1
        stream1.forEach(System.out::println);
    }
}

Output :

-9998
-9996
-9994
-9992
-9990

Example 3 :




// Java code for IntStream mapToInt
// (DoubleToIntFunction mapper)
import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.DoubleStream;
  
class GFG {
  
    // Driver code
    public static void main(String[] args)
    {
        // Creating a DoubleStream
        DoubleStream stream = DoubleStream.of(1.3, 2.4, 3.4,
                                              4.5, 5.7);
  
        // Using IntStream mapToInt(DoubleToIntFunction 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 * num * num));
  
        // Displaying the elements in stream1
        stream1.forEach(System.out::println);
    }
}

Output :

2
13
39
91
185

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