Java IntStream mapToDouble()用法及代碼示例

IntStream mapToDouble()返回DoubleStream，該DoubleStream包含將給定函數應用於此流的元素的結果。

注意：IntStream mapToDouble()是中間操作。這些操作總是很懶。在Stream實例上調用中間操作，並在完成處理後將中間實例作為輸出提供。
用法:

DoubleStream mapToDouble(IntToDoubleFunction mapper)

參數：

DoubleStream : 一係列原始雙值元素。這是Stream的雙重原始專業化。
mapper : 適用於每個元素的無狀態函數。

返回值：該函數返回一個DoubleStream，其中包括將給定函數應用於此流的元素的結果。

示例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); 
    } 
}

輸出：

2.0
4.0
6.0
8.0
10.0

示例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); 
    } 
}

輸出：

1.6666666666666667
2.0
2.3333333333333335
2.6666666666666665
3.0

示例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); 
    } 
}

輸出：

-0.9589242746631385
-0.27941549819892586
0.6569865987187891
0.9893582466233818
0.4121184852417566

相關用法

注：本文由純淨天空篩選整理自Sahil_Bansall大神的英文原創作品 IntStream mapToDouble() in Java。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。