Add this to your mainactivity:

@Override
public boolean onCreateOptionsMenu(Menu menu){
    // Create menu
    // See onOptionItemSelected for actions when clicked

    Menu settingsMenu = menu;
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.optionmenu, menu);

    MenuItem settingsMenuLogin = settingsMenu.findItem(R.id.settingsMenuExport);

return true;
}

and

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();


    if (id == R.id.settingsMenuExport) {
        // add additional check
        Intent i = new Intent(getApplicationContext(), export.class);
        startActivity(i);
    }
    return super.onOptionsItemSelected(item);
}

and create an xml in res\menu like this:

optionmenu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/settingsMenuExport"
        android:orderInCategory="100"
        android:title="Export"
        app:showAsAction="never" />
</menu>