Question

What is the equivalent in Java for this C# declaration ?

public class AsyncThreadPool<T, K> where T : IAsyncThread<K> {

and IAsyncThread is an interface

public interface IAsyncThread<T> 
{
    T GetAsyncUsedObject(); 
    void StartAsyncRequest();    
}

I have tried :

public class AsyncThreadPool<T extends IAsyncThread<K>, K  >

But is not correct, as T implements IAsyncThread<K> not extends it.

And I need in this class to use T.StartAsyncRequest() or similar

In C# it is:

T asyncThread = default(T);
asyncThread.StartAsyncRequest()

Answer 1

Your <T extends IAsyncThread<K>> is correct. Even though the class itself implements, not extends, the terminology for the generic definition is extends. If you wanted, you could use <T extends Object & IAsyncThread<K>> or <T extends Object, IAsyncThread<K>> but would be unnecessary.

For creating a member of type T, the only thing you really have at your disposal is to use a factory object.

public class AsyncThreadPool<T extends IAsyncThread<K>, K> {
    private final AsyncThreadFactory<T> factory;
    public ASyncThreadPool(AsyncThreadFactory<T> factory) {
        this.factory = factory;
    }
    public void foo() {
        T t = factory.createDefault();
        t.startAsyncRequest();
    }
}