Java LongStream peek()用法及代码示例

LongStream peek()是java.util.stream.LongStream中的方法。该函数返回由该流的元素组成的流，并在从结果流中消耗元素时对每个元素另外执行提供的操作。

用法:

LongStream peek(LongConsumer action)

Where, LongStream is a sequence of primitive
long-valued elements and the function returns 
a parallel LongStream and LongConsumer represents 
an operation that accepts a single long-valued argument.

示例1:在给定范围的流上执行求和。

// Java code for LongStream peek() 
// where the action performed is to get 
// sum of all elements in given range 
import java.util.*; 
import java.util.stream.LongStream; 
  
class GFG { 
  
    // Driver code 
    public static void main(String[] args) 
    { 
  
        // Creating a stream of longs 
        LongStream stream = LongStream.range(2L, 10L); 
  
        // performing action sum on elements of 
        // given range and storing the result in sum 
        long sum = stream.peek(System.out::println).sum(); 
  
        // Displaying the result of action performed 
        System.out.println("sum is : " + sum); 
    } 
}

输出：

2
3
4
5
6
7
8
9
sum is : 44

示例2:在给定范围的流上执行计数操作。

// Java code for LongStream peek() 
// where the action performed is to get 
// count of all elements in given range 
import java.util.*; 
import java.util.stream.LongStream; 
  
class GFG { 
  
    // Driver code 
    public static void main(String[] args) 
    { 
  
        // Creating a stream of longs 
        LongStream stream = LongStream.range(2L, 10L); 
  
        // performing action count on elements of 
        // given range and storing the result in Count 
        long Count = stream.peek(System.out::println).count(); 
  
        // Displaying the result of action performed 
        System.out.println("count : " + Count); 
    } 
}

输出：

2
3
4
5
6
7
8
9
count : 8

示例3:在给定范围的流上执行平均操作。

// Java code for LongStream peek() 
// where the action performed is to get 
// average of all elements in given range 
import java.util.*; 
import java.util.OptionalDouble; 
import java.util.stream.LongStream; 
  
class GFG { 
  
    // Driver code 
    public static void main(String[] args) 
    { 
  
        // Creating a stream of longs 
        LongStream stream = LongStream.range(2L, 10L); 
  
        // performing action average on elements of 
        // given range and storing the result in avg 
        OptionalDouble avg = stream.peek(System.out::println) 
                                 .average(); 
  
        // If a value is present, isPresent() 
        // will return true, else -1 is displayed. 
        if (avg.isPresent()) { 
            System.out.println("Average is : " + avg.getAsDouble()); 
        } 
        else { 
            System.out.println("-1"); 
        } 
    } 
}

输出：

2
3
4
5
6
7
8
9
Average is : 5.5

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 LongStream peek() 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。