IntStream mapToDouble() in Java

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

Note : IntStream mapToDouble() 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 :

DoubleStream mapToDouble(IntToDoubleFunction mapper)

Parameters :

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

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

Example 1 :

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// Java code for DoubleStream mapToDouble
// (IntToDoubleFunction 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 an IntStream
        IntStream stream = IntStream.of(2, 4, 6, 8, 10);
  
        // Using DoubleStream mapToLong(IntToDoubleFunction mapper)
        // to return a DoubleStream consisting of the
        // results of applying the given function to
        // the elements of this stream.
        DoubleStream stream1 = stream.mapToDouble(num -> (double)num);
  
        // Displaying the elements in stream1
        stream1.forEach(System.out::println);
    }
}

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Output :


2.0
4.0
6.0
8.0
10.0



Example 2 :











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// Java code for DoubleStream mapToDouble 


// (IntToDoubleFunction 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 an IntStream 


        IntStream stream = IntStream.range(5, 10); 


  


        // Using DoubleStream mapToLong(IntToDoubleFunction mapper) 


        // to return a DoubleStream consisting of the 


        // results of applying the given function to 


        // the elements of this stream. 


        DoubleStream stream1 = stream.mapToDouble(num -> (double)num / 3); 


  


        // Displaying the elements in stream1 


        stream1.forEach(System.out::println); 


    } 


} 



















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Output :


1.6666666666666667
2.0
2.3333333333333335
2.6666666666666665
3.0



Example 3 :











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// Java code for DoubleStream mapToDouble 


// (IntToDoubleFunction 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 an IntStream 


        IntStream stream = IntStream.range(5, 10); 


  


        // Using DoubleStream mapToLong(IntToDoubleFunction mapper) 


        // to return a DoubleStream consisting of the 


        // results of applying the given function to 


        // the elements of this stream. 


        DoubleStream stream1 = stream.mapToDouble(Math::sin); 


  


        // Displaying the elements in stream1 


        stream1.forEach(System.out::println); 


    } 


} 



















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Output :


-0.9589242746631385
-0.27941549819892586
0.6569865987187891
0.9893582466233818
0.4121184852417566




          
          
          
          

            

    

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