如何用拉姆达表达式进行筛选

如何用拉姆达表达式代替foreach进行结果筛选

ProductModel productmodel = new ProductModel();
 int? prostate_0 = 0;
        int? prostate_1 = 0;
        int? prostate_2 = 0;
        productmodel.Shop = _Shop;
        List<ProductModel> listcount = productmodel.Listcount();
        foreach (ProductModel item in listcount)
        {
            if (item.Pro_stateNum != null)
            {
                switch (item.Pro_state)
                {
                    case 0:{
                            prostate_0 = item.Pro_stateNum;
                        } break;
                    case 1:{
                            prostate_1 = item.Pro_stateNum;
                        } break;
                    case 2:{
                            prostate_2 = item.Pro_stateNum;
                        } break;
                }
            }
        }

 还可以简化下
List<ProductModel> listcount = productmodel.Listcount();
->
List<ProductModel> listcount = productmodel.Where(x => x.Pro_stateNum != null).Listcount();

productmodel.ForEach((item) => {
                switch (item.Pro_state)
                {
                    case 0:{
                            prostate_0 = item.Pro_stateNum;
                        } break;
                    case 1:{
                            prostate_1 = item.Pro_stateNum;
                        } break;
                    case 2:{
                            prostate_2 = item.Pro_stateNum;
                        } break;
                }
});

 productmodel.Foreach((item) => {
if (item.Pro_stateNum != null)
            {
                switch (item.Pro_state)
                {
                    case 0:{
                            prostate_0 = item.Pro_stateNum;
                        } break;
                    case 1:{
                            prostate_1 = item.Pro_stateNum;
                        } break;
                    case 2:{
                            prostate_2 = item.Pro_stateNum;
                        } break;
                }
            }
});