Java 中的 intstream maptodouble()
哎哎哎:# t0]https://www . geeksforgeeks . org/intstream-maptopoble-Java/
IntStream mapToDouble() 返回一个 DoubleStream，由给定函数应用于该流元素的结果组成。
注意: IntStream mapToDouble()是一个的中间操作。 这些操作总是偷懒。中间操作在流实例上被调用，在它们完成处理后，它们给出一个流实例作为输出。 语法:**
DoubleStream mapToDouble(IntToDoubleFunction mapper)
参数:
- 双流:原始双值元素的序列。这就是流的双原始特化。
- 映射器:应用于每个元素的无状态函数。
返回值:该函数返回一个双流，该双流由给定函数应用于该流元素的结果组成。
例 1 :
// 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);
}
}
输出:
2.0
4.0
6.0
8.0
10.0
例 2 :
// 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);
}
}
输出:
1.6666666666666667
2.0
2.3333333333333335
2.6666666666666665
3.0
例 3 :
// 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);
}
}
输出:
-0.9589242746631385
-0.27941549819892586
0.6569865987187891
0.9893582466233818
0.4121184852417566
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