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Java LongStream mapToInt()用法及代码示例


LongStream mapToInt()返回一个IntStream，其中包括将给定函数应用于此流的元素的结果。

注意：LongStream mapToInt()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 mapToInt(LongToIntFunction mapper)

参数：


  1. LongStream : 一系列原始long值元素。这是Stream的长期原始专业化。
  2. mapper : 适用于每个元素的无状态函数。

返回值：该函数返回一个IntStream，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 mapToInt 
// (LongToIntFunction mapper) 
import java.util.*; 
import java.util.stream.IntStream; 
import java.util.stream.LongStream; 
  
class GFG { 
  
    // Driver code 
    public static void main(String[] args) 
    { 
        // Creating a LongStream 
        LongStream stream = LongStream.of(2L, 4L, 6L, 8L, 10L); 
          
        // Using LongStream mapToInt(LongToIntFunction mapper) 
        // to return an IntStream consisting of the 
        // results of applying the given function to  
        // the elements of this stream. 
        IntStream stream1 = stream.mapToInt(num -> (int) num);  
  
        // Displaying the elements in stream1 
        stream1.forEach(System.out::println); 
    } 
}

输出：

2
4
6
8
10

示例2:

// Java code for LongStream mapToInt 
// (LongToIntFunction mapper) 
import java.util.*; 
import java.util.stream.IntStream; 
import java.util.stream.LongStream; 
  
class GFG { 
  
    // Driver code 
    public static void main(String[] args) 
    { 
        // Creating a LongStream 
        LongStream stream = LongStream.of(1L, 2L, 3L, 4L, 5L); 
          
        // Using LongStream mapToInt(LongToIntFunction mapper) 
        // to return an IntStream consisting of the 
        // results of applying the given function to  
        // the elements of this stream. 
        IntStream stream1 = stream.mapToInt(num -> 
                                   (int) num + Integer.MAX_VALUE);  
  
        // Displaying the elements in stream1 
        stream1.forEach(System.out::println); 
    } 
}

输出：

-2147483648
-2147483647
-2147483646
-2147483645
-2147483644

示例3:

// Java code for LongStream mapToInt 
// (LongToIntFunction mapper) 
import java.util.*; 
import java.util.stream.IntStream; 
import java.util.stream.LongStream; 
  
class GFG { 
  
    // Driver code 
    public static void main(String[] args) 
    { 
        // Creating a LongStream 
        LongStream stream = LongStream.range(2L, 7L); 
          
        // Using LongStream mapToInt(LongToIntFunction mapper) 
        // to return an IntStream consisting of the 
        // results of applying the given function to  
        // the elements of this stream. 
        IntStream stream1 = stream.mapToInt(num -> 
                                    (int) num - 2);  
  
        // Displaying the elements in stream1 
        stream1.forEach(System.out::println); 
    } 
}

输出：

0
1
2
3
4


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注：本文由纯净天空筛选整理自Sahil_Bansall大神的英文原创作品 LongStream mapToInt() in Java with Examples。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。