title: How to use Guice's Injector?
body: <p>I'm in process of learning Guice and I don't clearly understand how to use <code>Injector</code> instance. It's better to create <code>Injector</code> instance once on application bootstrap, and make it public singleton?</p>
  
  <p>And is it true that we always must use <code>Injector#getInstance(SomeClass.class)</code> to get classes where we putted Guice's <code>@Inject</code> annotations? </p>