Java DoubleStream mapToLong()用法及代碼示例

DoubleStream mapToLong()返回LongStream，該LongStream包括將給定函數應用於此流的元素的結果。

注意：DoubleStream mapToLong()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:

LongStream mapToLong(DoubleToLongFunction 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LongStream，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 LongStream mapToLong 
// (DoubleToLongFunction 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 a DoubleStream 
        DoubleStream stream = DoubleStream.of(3.3, 6.5, 16.4, 
                                              8.7, 10.4); 
  
        // Using LongStream mapToLong(DoubleToLongFunction mapper) 
        // to return a LongStream consisting of the 
        // results of applying the given function to 
        // the elements of this stream. 
        LongStream stream1 = stream.mapToLong(num -> (long)num); 
  
        // Displaying the elements in stream1 
        stream1.forEach(System.out::println); 
    } 
}

輸出：

示例2:

// Java code for LongStream mapToLong 
// (DoubleToLongFunction 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 a DoubleStream 
        DoubleStream stream = DoubleStream.of(3.3, 6.5, 16.4, 
                                              8.7, 10.4); 
  
        // Using LongStream mapToLong(DoubleToLongFunction mapper) 
        // to return a LongStream consisting of the 
        // results of applying the given function to 
        // the elements of this stream. 
        LongStream stream1 = stream.mapToLong(num -> (long)num - 10); 
  
        // Displaying the elements in stream1 
        stream1.forEach(System.out::println); 
    } 
}

輸出：

-7
-4
6
-2
0

示例3:

// Java code for LongStream mapToLong 
// (DoubleToLongFunction 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 a DoubleStream 
        DoubleStream stream = DoubleStream.of(3.3, 6.5, 16.4, 
                                              8.7, 10.4); 
  
        // Using LongStream mapToLong(DoubleToLongFunction mapper) 
        // to return a LongStream consisting of the 
        // results of applying the given function to 
        // the elements of this stream. 
        LongStream stream1 = stream.mapToLong(num -> (long)(2 * num * num)); 
  
        // Displaying the elements in stream1 
        stream1.forEach(System.out::println); 
    } 
}

輸出：

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 DoubleStream mapToLong() 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。