Java Stream mapToInt()用法及代码示例

Stream mapToInt(ToIntFunction mapper)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。

流mapToInt(ToIntFunction mapper)是一个中间操作。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:

IntStream mapToInt(ToIntFunction<? super T> mapper)

Where, IntStream is a sequence of primitive 
int-valued elements and T is the type 
of stream elements. mapper is a stateless function 
which is applied to each element and the function
returns the new stream.

示例1:mapToInt()具有将流元素除以3的函数。

// Java code for Stream mapToInt 
// (ToIntFunction mapper) to get a 
// IntStream by applying the given function 
// to the elements of this stream. 
import java.util.*; 
  
class GFG { 
  
    // Driver code 
    public static void main(String[] args) 
    { 
  
        // Creating a list of Strings 
        List<String> list = Arrays.asList("3", "6", "8",  
                                            "14", "15"); 
  
        // Using Stream mapToInt(ToIntFunction mapper) 
        // and displaying the corresponding IntStream 
        list.stream().mapToInt(num -> Integer.parseInt(num)) 
                     .filter(num -> num % 3 == 0) 
                     .forEach(System.out::println); 
    } 
}

输出：

3
6
15

示例2:mapToInt()在执行具有其长度的映射字符串的操作后返回IntStream。

// Java code for Stream mapToInt 
// (ToIntFunction mapper) to get a 
// IntStream by applying the given function 
// to the elements of this stream. 
import java.util.*; 
  
class GFG { 
  
    // Driver code 
    public static void main(String[] args) 
    { 
  
        // Creating a list of Strings 
        List<String> list = Arrays.asList("Geeks", "for", "gfg", 
                                          "GeeksforGeeks", "GeeksQuiz"); 
  
        // Using Stream mapToInt(ToIntFunction mapper) 
        // and displaying the corresponding IntStream 
        // which contains length of each element in 
        // given Stream 
        list.stream().mapToInt(str -> str.length()).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 Stream 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。