activity_main error
<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>
