Java 中的 IntStream peek()，带示例
原文:https://www . geesforgeks . org/int stream-peek-in-Java-with-examples/
IntStream peek() 是 java.util.stream.IntStream 中的一个方法，该函数返回一个由这个流的元素组成的流，当元素从结果流中被消耗掉时，还会对每个元素执行提供的操作。
语法:
IntStream peek(IntConsumer action)
Where, IntStream is a sequence of primitive
int-valued elements and the function returns
a parallel IntStream and IntConsumer represents
an operation that accepts a single int-valued argument.
示例 1 : 对给定范围的流执行求和。
// Java code for IntStream peek()
// where the action performed is to get
// sum of all elements in given range
import java.util.*;
import java.util.stream.IntStream;
class GFG {
// Driver code
public static void main(String[] args) {
// Creating a stream of integers
IntStream stream = IntStream.range(2, 10);
// performing action sum on elements of
// given range and storing the result in sum
int 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 : 对给定范围的流执行计数操作。
// Java code for IntStream peek()
// where the action performed is to get
// count of all elements in given range
import java.util.*;
import java.util.stream.IntStream;
class GFG {
// Driver code
public static void main(String[] args) {
// Creating a stream of integers
IntStream stream = IntStream.range(2, 10);
// 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 : 对给定范围的流执行平均运算。
// Java code for IntStream 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.IntStream;
class GFG {
// Driver code
public static void main(String[] args) {
// Creating a stream of integers
IntStream stream = IntStream.range(2, 10);
// 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
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