title: Property must be initialized or be abstract
body: <p>How to declare class field? Like we can have it in java:</p>
  <pre><code>protected SharedPreferences mSharedPreferences;
  </code></pre>
  <p>And later in <code>onCreate()</code>:</p>
  <pre><code>mSharedPreferences = PreferenceManager.getDefaultSharedPreferences(this)
  </code></pre>
  <p>Now I can use it anywhere I want (in subclasses of this base activity).</p>
  <p>I try to do same in Kotlin:</p>
  <pre><code>protected var sharedPreferences : SharedPreferences
  </code></pre>
  <p>And in <code>onCreate()</code>:</p>
  <pre><code>sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this)
  </code></pre>
  <p>But I get a warning: &quot;Property must be initialized or be abstract&quot;</p>