title: can not find the declaration of element "Android support constraint ConstraintLayout"
body: <p>I don't know what type of error is this? </p>
  
  <p>Image One</p>
  
  <p><a href="https://i.stack.imgur.com/4Mnw7.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4Mnw7.jpg" alt="enter image description here"></a></p>
  
  <p>Image Two</p>
  
  <p><a href="https://i.stack.imgur.com/awivQ.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/awivQ.jpg" alt="enter image description here"></a></p>
  
  <p>I've even noticed that layout place was in <code>res</code> folder now it's changed by itself in java folder? Why is that happening to my application? and how can I solve it?</p>