IntStream findFirst()返回描述此流的第一个元素的OptionalInt(一个可能包含也可能不包含非null值的容器对象),或者返回空的OptionalInt(如果该流为空)
用法:
OptionalInt findFirst() Where, OptionalInt is a container object which may or may not contain a non-null value and the function returns an OptionalInt describing the first element of this stream, or an empty OptionalInt if the stream is empty.
注意:findFirst()是流接口的terminal-short-circuiting操作。此方法返回满足中间操作的任何第一个元素。
示例1:整数流上的findFirst()方法。
// Java code for IntStream findFirst()
// which returns an OptionalInt describing
// first element of the stream, or an
// empty OptionalInt if the stream is empty.
import java.util.*;
import java.util.stream.IntStream;
class GFG {
// Driver code
public static void main(String[] args)
{
// Creating an IntStream
IntStream stream = IntStream.of(6, 7, 8, 9);
// Using IntStream findFirst() to return
// an OptionalInt describing first element
// of the stream
OptionalInt answer = stream.findFirst();
// if the stream is empty, an empty
// OptionalInt is returned.
if (answer.isPresent())
System.out.println(answer.getAsInt());
else
System.out.println("no value");
}
}
输出:
6
注意:如果流没有遇到顺序,则可以返回任何元素。
示例2:findFirst()方法返回第一个可被4整除的元素。
// Java code for IntStream findFirst()
// which returns an OptionalInt describing
// first element of the stream, or an
// empty OptionalInt if the stream is empty.
import java.util.OptionalInt;
import java.util.stream.IntStream;
class GFG {
// Driver code
public static void main(String[] args)
{
// Creating an IntStream
IntStream stream = IntStream.of(4, 5, 8, 10, 12, 16)
.parallel();
// Using IntStream findFirst().
// Executing the source code multiple times
// must return the same result.
// Every time you will get the same
// Integer which is divisible by 4.
stream = stream.filter(num -> num % 4 == 0);
OptionalInt answer = stream.findFirst();
if (answer.isPresent())
System.out.println(answer.getAsInt());
}
}
输出:
4
相关用法
- Java LongStream findFirst()用法及代码示例
- Java Stream findFirst()用法及代码示例
- Java IntStream of()用法及代码示例
- Java IntStream sum()用法及代码示例
- Java IntStream min()用法及代码示例
- Java IntStream builder()用法及代码示例
- Java IntStream max()用法及代码示例
- Java IntStream summaryStatistics()用法及代码示例
- Java IntStream limit()用法及代码示例
- Java IntStream asLongStream()用法及代码示例
- Java IntStream asDoubleStream()用法及代码示例
- Java IntStream boxed()用法及代码示例
- Java IntStream mapToObj()用法及代码示例
- Java IntStream mapToLong()用法及代码示例
- Java IntStream skip()用法及代码示例
注:本文由纯净天空筛选整理自Sahil_Bansall大神的英文原创作品 IntStream findFirst() in Java。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。