Is there a Java equivalent to C#'s 'yield' keyword?

Question

I know there is no direct equivalent in Java itself, but perhaps a third party?

It is really convenient. Currently I\'d like to implement an iterator that yields all

Answer 1

I just published another (MIT-licensed) solution here, which launches the producer in a separate thread, and sets up a bounded queue between the producer and the consumer, allowing for buffering, flow control, and parallel pipelining between producer and consumer (so that the consumer can be working on consuming the previous item while the producer is working on producing the next item).

You can use this anonymous inner class form:

Iterable iterable = new Producer(queueSize) {
    @Override
    public void producer() {
        produce(someT);
    }
};

for example:

for (Integer item : new Producer(/* queueSize = */ 5) {
    @Override
    public void producer() {
        for (int i = 0; i < 20; i++) {
            System.out.println("Producing " + i);
            produce(i);
        }
        System.out.println("Producer exiting");
    }
}) {
    System.out.println("  Consuming " + item);
    Thread.sleep(200);
}

Or you can use lambda notation to cut down on boilerplate:

for (Integer item : new Producer(/* queueSize = */ 5, producer -> {
    for (int i = 0; i < 20; i++) {
        System.out.println("Producing " + i);
        producer.produce(i);
    }
    System.out.println("Producer exiting");
})) {
    System.out.println("  Consuming " + item);
    Thread.sleep(200);
}