title: why there are two way of using thread in java?
body: <p>I know there are two ways to use a thread in java:</p>
  
  <ol>
  <li>implement Runable</li>
  <li>extend Thread</li>
  </ol>
  
  <p>I also know implementing  <em>Runable</em> is better than extending  <em>Thread</em>. </p>
  
  <p>But why there are two ways - why not only one?</p>
  
  <p>If implementing <em>Runnable</em> is a better approach, why is there another option? </p>
  
  <p>What would be wrong with having only one option ?</p>