Question

In Brian Goetz’s article about safe construction techniques you could read:

[…] often when an object owns a thread, either that thread is an inner class or we pass the this reference to its constructor (or the class itself extends the Thread class). If an object is going to own a thread, it is best if the object provides a start() method, just like Thread does, and starts the thread from the start() method instead of from the constructor. While this does expose some implementation details (such as the possible existence of an owned thread) of the class via the interface, which is often not desirable, in this case the risks of starting the thread from the constructor outweigh the benefit of implementation hiding.

I guess that with the following code there shouldn’t be any problem. Since it is not an inner class nor I am passing a reference of this. But I want to be sure.

private Controller controller;
private View view;

public Facade() {
    view = new View();
    controller = new Controller(view);
    controller.start();
}

I keep getting NetBeans warnings though… So is this code safe or unsafe?

Answer 1

The main reason do not start thread in constructor – do not expose “this” before “this” is created (after constructor executed). In your code I do not see such code like:

new Thread(this);

So it should be fine.