title: activity_main error
body: <p><code>Activity_main.xml</code> is present but still its giving a error in <code>MainActivity.java</code>
  Can anyone tell me what is the error here?</p>
  
  <pre><code>package com.example.hellotabwidget;
  
  import android.R;
  import android.app.Activity;
  import android.os.Bundle;
  import android.view.Menu;
  
  public class MainActivity extends Activity {
  
      @Override
      public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
      }
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
          getMenuInflater().inflate(R.menu.activity_main, menu);
          return true;
      }
  }
  </code></pre>
  
  <blockquote>
    <p>activity_main cannot be resolved or is not a field</p>
  </blockquote>