赋值一个list和创建一个list有什么区别

TeaDao teaDao = new TeaDao(getContext(), "tea.db");
List TeaBeanlists = new ArrayList();
TeaBeanlists = teaDao.showAllTea();
for(TeaBean teabean:TeaBeanlists ){
Log.e("............name", teabean.getName());
Log.e("............id", teabean.getId()+"");
Log.e("............acount", teabean.getAcount()+"");
Log.e("............content", teabean.getContent());
}
与
TeaDao teaDao = new TeaDao(getContext(), "tea.db");
List TeaBeanlists = teaDao.showAllTea();

    for(TeaBean teabean:TeaBeanlists ){
        Log.e("............name", teabean.getName());
        Log.e("............id", teabean.getId()+"");
        Log.e("............acount", teabean.getAcount()+"");
        Log.e("............content", teabean.getContent());

    }为什么第二个直接赋值的可以显示，而第一个先创建在赋值确无法显示日志内容？