Question

我有一个列表，我试图在其中添加另一个列表，但它总是抛出错误

List Products;

for(final i productsFromApi){
      var tmpArray = [];

      tmpArray['name'] = i['name'];
      tmpArray['price'] = i['price'];
      tmpArray['quantity'] = i['quantity'];

      Products.add(tmpArray);
 }

 print('final list of products');
 print(products); // throws an error: add called on null

Answer 1

您需要初始化列表

List products = [];

for(final i in productsFromApi){
      var productMap = {
          'name': i['name'],
          'price': i['price'],
          'quantity': i['quantity'],
      }

      products.add(productMap);
 }

 print('final list of products');
 print(products);

您应该考虑键入列表，因为如果不够小心，当前代码可能会导致错误。像这样：

List<Product> products = [];
Product myProduct = Product(name: "Product 1", price: 2.0, quantity: 3);
products.add(myProduct);

如何将键值对列表推入/插入到dart / flutter中的列表中？

1 个答案: