Java中的 LongStream average() 示例

Java 8 中的Java .util.stream.LongStream 处理原始 Long。它有助于以一种新的方式解决数组中的最大值，数组中的最小值，数组中所有元素的总和以及数组中所有值的平均值等旧问题。 LongStream average()返回一个 OptionalDouble 描述此流的元素的算术平均值，如果此流为空，则返回一个空的可选项。

句法 ：

OptionalDouble average()

Where, OptionalDouble is a container object 
which may or may not contain a double value.

下面给出了一些示例，以更好地理解该函数。

示例 1：

Java

// Java code for LongStream average()
import java.util.*;
import java.util.stream.LongStream;
 
class GFG {
 
    // Driver code
    public static void main(String[] args)
    {
        // creating a stream
        LongStream stream = LongStream.of(2L, 3L, 4L,
                                          5L, 6L, 7L, 8L);
 
        // OptionalDouble is a container object
        // which may or may not contain a
        // double value.
        OptionalDouble obj = stream.average();
 
        // If a value is present, isPresent() will
        // return true and getAsDouble() will
        // return the value
        if (obj.isPresent()) {
            System.out.println(obj.getAsDouble());
        }
        else {
            System.out.println("-1");
        }
    }
}

输出：

5.0

示例 2：

Java

// Implementation of LongStream average()
import java.util.*;
import java.util.stream.LongStream;
 
class GFG {
 
    // Driver code
    public static void main(String[] args)
    {
        // creating a stream
        LongStream stream = LongStream.of(2L, 3L, 3L, 4L, 6L, 8L, 8L);
 
        // OptionalDouble is a container object
        // which may or may not contain a
        // double value.
        OptionalDouble obj = stream.average();
 
        // If a value is present, isPresent() will
        // return true and getAsDouble() will
        // return the value
        if (obj.isPresent()) {
            System.out.println(obj.getAsDouble());
        }
        else {
            System.out.println("-1");
        }
    }
}

输出：

4.857142857142857