Java 等待集合中新对象的线程

Question

I have one thread which should execute some action when new object is added to collection. This collection is modified by several Callables. Thread which waits for new elements should be easy stopped after some time by boolean flag 'stopped'.

What are the possible ways for implementing that? I didn't find good examples of implementing that.

Answer 1

Well, you could wrap your collection in a custom one and register a listener. Example with LinkedBlockingQueue :

public class MyCollection<T> extends LinkedBlockingQueue<T> {
    
    private final MyListener<T> listener;

    public MyCollection(MyListener<T> listener) {
        this.listener = listener;
    }

    @Override
    public void put(T t) throws InterruptedException {
        super.put(t);
        listener.onPut(t);
    }
    
}

public class MyListener<T> {
    
    private final ExecutorService executorService = Executors.newSingleThreadExecutor();
    
    public void onPut(T t) {
            executorService.submit(() -> doSomething(t));
    }
    
    public void stop() {
        executorService.shutdown();
        // optional call to awaitTermination() here..
    }
    
}