Java 中的流映射(带示例)
原文:https://www . geesforgeks . org/stream-maptoint-Java-examples/
流映射函数映射器(ToIntFunction mapper) 返回一个包含给定函数应用于该流元素的结果的输入流。
流映射是一个的中间操作。这些操作总是偷懒。中间操作在流实例上被调用，在它们完成处理后，它们给出一个流实例作为输出。
*语法:*
**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()具有打印流元素的操作，如果可被 3 整除。
// 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
*例 2 :* mapToInt()执行映射字符串及其长度的操作后返回 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:
5
3
3
13
9
版权属于：月萌API www.moonapi.com，转载请注明出处
