title: Define a multi interface Variable
body: <p>I want to define a variable that implement 2 interface.
  Imove and Ijump are 2 interface.</p>
  <pre><code>class b implements Imove,Ijump {...}
  class a implements Imove,Ijump {...}
  Imove,Ijump player = new a();
  Imove,Ijump player = new b();
  player.Jump();
  player.Move();
  </code></pre>