Rename Android project package issue in Eclipse - R cannot be resolved to a variable

	public void callFc() 
	throws IndexOutOfBoundsException, ArithmeticException
	{
         // my code for example:
         String[] sArray = {"aa","bb"};
         String str = sArray[5]; // IndexOutOfBoundsException

         int n = 5 / 0; // ArithmeticException
        }

public void someFC (){
try{
     callFc();
    }
 catch(IndexOutOfBoundsException e){
      Log.e("TAG", e.toString());
  }
 catch(ArithmeticException e2){ 
      Log.e2("TAG",e2.toString()); 
  }
}

// image from res/drawable
	int resID = getResources().getIdentifier("my_image", 
			"drawable", getPackageName());
// view
	int resID = getResources().getIdentifier("my_resource", 
			"id", getPackageName());

// string
	int resID = getResources().getIdentifier("my_string", 
			"string", getPackageName());

static boolean mbThemeLight = false;

 @Override
    public void onCreate(Bundle savedInstanceState) {
         if(mbThemeLight)
        setTheme(android.R.style.Theme_Light);
        super.onCreate(savedInstanceState);
        // bla bla bla..........
    }

private void switchTheme(){
 mbThemeLight = true;
 this.recreate();
}

public class HoriziontalScrollActivity extends Activity {
	TextView txtV;
	Context cntx;
	
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        txtV = (TextView)findViewById(R.id.idLabel);
        cntx = this;
        StringBuilder strBuild = new StringBuilder();

        // enter your date of birth
        Calendar dateOfYourBirth = new GregorianCalendar(1998, Calendar.SEPTEMBER, 17);
        Calendar today = Calendar.getInstance();
        int yourAge = today.get(Calendar.YEAR) - dateOfYourBirth.get(Calendar.YEAR);
        dateOfYourBirth.add(Calendar.YEAR, yourAge);
        if (today.before(dateOfYourBirth)) {
            yourAge--;
        }  
        strBuild.append("You are " + yourAge + " old!");
         txtV.setText(strBuild);
    }
}

<manifest xmlns:android="//schemas.android.com/apk/res/android"
    package="com.myweb.mypackage"
    android:installLocation="preferExternal"