title: Incompatible types: getFragmentManager not working
body: <p>After importing android.support.v4.app.FragmentManager it still shows an error concerning getFragmentManager. It says <code>Required: android.support.v4.app.Fragmentmanager, but Found: android.app.FragmentManager.</code> </p>
  
  <p>Which is weird because the latter isn't even imported into the library. I'am working in API 15 therefore I read in other topics the reason could be that I have to use getSupportFragmentManager.</p>
  
  <p>Unfortunately, I can't reach SupportFragmentManager what is going wrong? Might be a problem with the import library?</p>
  
  <pre><code>package com.example.slidenerdinterfrag;
  
  import android.app.Activity;
  import android.support.v4.app.FragmentManager;
  import android.support.v7.app.AppCompatActivity;
  import android.os.Bundle;
  
  public class MainActivity extends Activity implements Communicator{
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
      }
  
      @Override
      public void respond(String data) {
          FragmentManager manager=getFragmentManager();
          FragmentB f2= (FragmentB) manager.findFragmentById(R.id.fragment2);
          f2.changeText(data);
      }
  }
  </code></pre>