activity_main cannot be resolved or is not a field

Question

i am a new android developer stucked in this error, I've read other threads, following the instructions but there is no way to solve it. This is the file res/layout/activity_main.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >


    <Button
        android:id="@+id/button1"
        android:layout_width="300dp"
        android:layout_height="225dp"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true" 
        android:textSize="30sp"
        android:textColor="#613def"
        android:textStyle="bold"
        android:background="@drawable/microphonegrey"/>

</RelativeLayout>

in the class MainActivity.java:

 @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

with the Error "activity_main cannot be resolved or is not a field"

I choose Create field 'activity_main' in type 'menu'

The field is created, but then I see this message in the console:

[2014-07-27 23:11:30 - TestProject] R.java was modified manually! Reverting to generated version!

over and over again..., cleaning the project, saving...With the same result, the import clause is the correct in the file:

import mypackage.R, not android.R

Answer 1

If it is in your res/layout folder your code should look like this:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
  }

Answer 2

Clean project then try to run it. I faced the same problem. You can also do this:

Remove from your code following imports import android.R; or import your.application.packagename.R;

Now clean the project and run it.