LongStream mapToDouble() in Java
LongStream mapToDouble() returns a DoubleStream consisting of the results of applying the given function to the elements of this stream.
Note : LongStream 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(LongToDoubleFunction mapper)
Parameters :
- DoubleStream : A sequence of primitive double-valued elements. This is the double primitive specialization of Stream.
- 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 :
// Java code for DoubleStream mapToDouble// (LongToDoubleFunction mapper)import java.util.*;import java.util.stream.LongStream;import java.util.stream.DoubleStream;  class GFG {      // Driver code    public static void main(String[] args)    {        // Creating an LongStream        LongStream stream = LongStream.of(2L, 4L, 6L, 8L, 10L);          // Using DoubleStream mapToLong(LongToDoubleFunction 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);    }} |
Output :
2.0 4.0 6.0 8.0 10.0
Example 2 :
// Java code for DoubleStream mapToDouble// (LongToDoubleFunction mapper)import java.util.*;import java.util.stream.LongStream;import java.util.stream.DoubleStream;  class GFG {      // Driver code    public static void main(String[] args)    {        // Creating an LongStream        LongStream stream = LongStream.range(5L, 10L);          // Using DoubleStream mapToLong(LongToDoubleFunction 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 / 5);          // Displaying the elements in stream1        stream1.forEach(System.out::println);    }} |
Output :
1.0 1.2 1.4 1.6 1.8
Example 3 :
// Java code for DoubleStream mapToDouble// (LongToDoubleFunction mapper)import java.util.*;import java.util.stream.LongStream;import java.util.stream.DoubleStream;  class GFG {      // Driver code    public static void main(String[] args)    {        // Creating an LongStream        LongStream stream = LongStream.range(5L, 10L);          // Using DoubleStream mapToLong(LongToDoubleFunction 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::cos);          // Displaying the elements in stream1        stream1.forEach(System.out::println);    }} |
Output :
0.28366218546322625 0.9601702866503661 0.7539022543433046 -0.14550003380861354 -0.9111302618846769
