title: Cannot resolve method 'findViewById(int)' in Fragment of ViewPager
body: <p>Hello, I have a Fragment for a ViewPager:</p>
  
  <pre><code>package my.test.myapplication;
  
  import android.os.Bundle;
  import android.support.annotation.Nullable;
  import android.support.v4.app.Fragment;
  import android.view.LayoutInflater;
  import android.view.View;
  import android.view.ViewGroup;
  import android.widget.Button;
  
  public class Fragment1 extends Fragment {
  
      private Button btn;
      @Nullable
      @Override
      public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
          // point A
          return  inflater.inflate(R.layout.frag1,container,false);
      }
  }
  </code></pre>
  
  <p>When I would add this under point A, it comes a error message:</p>
  
  <pre><code>public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
      // point A
      btn = (Button) findViewById(R.id.button);
      return  inflater.inflate(R.layout.frag1,container,false);
  }
  </code></pre>
  
  <p>The error message:</p>
  
  <pre><code>Cannot resolve method 'findViewById(int)'
  </code></pre>
  
  <p>What can I do?</p>