title: getFilesDir() android function is undefined if i dont extend my class with activity
body: <p>If i have my class as </p>
  
  <pre><code>import java.io.File;
  
  import java.io.FileOutputStream;
  
  //Extends Activity
  
  public class MyClass extends Activity
  {
  
  File fileDir = getFilesDir(); //no error
  
     . ....    
  }
  </code></pre>
  
  <p>But if i don't extend MyClass , i get an error saying "getFilesDir()" undefined.</p>
  
  <p>some thing like </p>
  
  <pre><code>   public class MyClass2
      {
  
      ....
  
      File fileDir = getFilesDir(); //error
  
      }
  </code></pre>