[FIXED] Can't use List in spring boot

Issue

I would like to share my problem with you. I can't use two List in a function but when a remove a List the program success. My Code :

    com.poly.dao.ProductDao dao;
    com.poly.dao.CategoryDAO dao2;
    ServletContext app;
    @RequestMapping("/product/index")
    public String index(Model model) {
        com.poly.entity.Product item = new Product();
        model.addAttribute("item",item);
        List<Category> cate = dao2.findAll();
        List<Product> items = dao.findAll();
        model.addAttribute("items",items);
        model.addAttribute("cate",cate);
        
        return("admin/product/admin-add-product");
    }

When I remove a List<Category> cate = dao2.findAll(); the program run but when I add this the program notices erro : java.lang.NullPointerException: Cannot invoke "com.poly.dao.CategoryDAO.findAll()" because "this.dao2" is null

I don't understand this erro. Anyone help my pls thanksss

Solution

Oh i found a solution for my code I forgot write @Autowired above dao and dao2. This is a solution for code.

Answered By - sunsynd