Java DoubleStream mapToLong()用法及代码示例

DoubleStream mapToLong()返回LongStream，该LongStream包括将给定函数应用于此流的元素的结果。

注意：DoubleStream mapToLong()是中间操作。这些操作总是很懒。在Stream实例上调用中间操作，并在完成处理后将中间实例作为输出提供。
用法:

LongStream mapToLong(DoubleToLongFunction mapper)

参数：

DoubleStream : 一系列原始双值元素。这是Stream的双重原始专业化。
mapper : 适用于每个元素的无状态函数。

返回值：该函数返回LongStream，其中包括将给定函数应用于此流的元素的结果。

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); 
    } 
}

输出：

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); 
    } 
}

输出：

-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); 
    } 
}

输出：

相关用法

注：本文由纯净天空筛选整理自Sahil_Bansall大神的英文原创作品 DoubleStream mapToLong() in Java。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。