[英]How to create an infinite stream with Java 8
Yes, there is an easy way:是的,有一个简单的方法:
IntStream.iterate(0, i -> i + 2);
With as usecase:作为用例:
IntStream.iterate(0, i -> i + 2)
.limit(100)
.forEach(System.out::println);
Which prints out 0 to 198 increasing in steps of 2.它打印出 0 到 198,以 2 的步长递增。
The generic method is:通用方法是:
Stream.iterate(T seed, UnaryOperator<T> f);
The latter may be more uncommon in usage.后者在使用中可能更不常见。
Here is an example:下面是一个例子:
PrimitiveIterator.OfInt it = new PrimitiveIterator.OfInt() {
private int value = 0;
@Override
public int nextInt() {
return value++;
}
@Override
public boolean hasNext() {
return true;
}
};
Spliterator.OfInt spliterator = Spliterators.spliteratorUnknownSize(it,
Spliterator.DISTINCT | Spliterator.IMMUTABLE |
Spliterator.ORDERED | Spliterator.SORTED);
IntStream stream = StreamSupport.intStream(spliterator, false);
It's a bit verbose, as you see.如您所见,这有点冗长。 To print the first 10 elements of this stream:
要打印此流的前 10 个元素:
stream.limit(10).forEach(System.out::println);
You can ofcourse also transform the elements, like you do in your Scala example:您当然也可以转换元素,就像您在 Scala 示例中所做的那样:
IntStream plusTwoStream = stream.map(n -> n + 2);
Note that there are built-in infinite streams such as java.util.Random.ints()
which gives you an infinite stream of random integers.请注意,有内置的无限流,例如
java.util.Random.ints()
,它为您提供无限的随机整数流。
There is another possible solution in Java 8 : Java 8 中有另一种可能的解决方案:
AtomicInteger adder = new AtomicInteger();
IntStream stream = IntStream.generate(() -> adder.getAndAdd(2));
Important: an order of numbers is preserved only if the stream is sequential.重要提示:仅当流是顺序的时才会保留数字顺序。
It's also worth noting that a new version of the IntStream.iterate
has been added since Java 9 :还值得注意的是,自Java 9以来添加了新版本的
IntStream.iterate
:
static IntStream iterate(int seed,
IntPredicate hasNext,
IntUnaryOperator next);
Examples:例子:
IntStream stream = IntStream.iterate(0, i -> i >= 0, i -> i + 2);
IntStream.iterate(0, i -> i < 10, i -> i + 2).forEach(System.out::println);
You can build your own InfiniteStream by implementing stream and consumer and compose both and may will need queue to queueing your data as :您可以通过实现流和消费者来构建自己的 InfiniteStream 并组合两者,并且可能需要队列将您的数据排队为:
public class InfiniteStream<T> implements Consumer<T>, Stream<T> {
private final Stream<T> stream;
private final Queueing q;
...
public InfiniteStream(int length) {
this.q = new Queueing(this.length);
this.stream = Stream.generate(q);
...
}
//implement stream methods
//implement accept
}
check full code here https://gist.github.com/bassemZohdy/e5fdd56de44cea3cd8ff在此处查看完整代码https://gist.github.com/bassemZohdy/e5fdd56de44cea3cd8ff
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