Menu items doesn't show up on the actionbar [duplicate]

Answer 1

Try in your activity onCreate() :

ActionBar bar = getSupportActionBar();
bar.setTitle(R.string.app_name);

and then :

    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {    
        menu.clear();
        getSupportMenuInflater().inflate(R.menu.menu_activity, menu);
        return super.onPrepareOptionsMenu(menu);
    }