title: This view is not constrained android studio
body: <p>i'm new in android studio and just installed 3.1.3, when i create new project, there no "hello world!" text in my layout. even though, in tutorial, when we create new project, "hello world" text will appear automatically. then, i try to follow instruction in this link</p>
  
  <p><a href="https://stackoverflow.com/questions/37817537/this-view-is-not-constrained#comment80440773_42835746">This view is not constrained</a></p>
  
  <p>i have tried to use "infer constraints" and it doesnt work, how can i fix this??</p>
  
  <p><img src="https://i.stack.imgur.com/rtKpF.png" alt="erorr picture"></p>