安卓购物车功能的实现代码

实现一个安卓购物车功能的代码可以分为以下几个步骤：

1. 创建一个商品类，包含商品名称、价格和数量等属性。

public class Product {
    private String name;
    private double price;
    private int quantity;

    public Product(String name, double price, int quantity) {
        this.name = name;
        this.price = price;
        this.quantity = quantity;
    }

    // getter and setter methods
}

2. 创建一个购物车类，包含添加商品、移除商品、获取购物车总价等方法。

public class ShoppingCart {
    private List<Product> productList = new ArrayList<>();

    public void addProduct(Product product) {
        productList.add(product);
    }

    public void removeProduct(Product product) {
        productList.remove(product);
    }

    public double getTotalPrice() {
        double totalPrice = 0;
        for (Product product : productList) {
            totalPrice += product.getPrice() * product.getQuantity();
        }
        return totalPrice;
    }

    // getter and setter methods
}

3. 在界面中添加一个列表用于显示购物车中的商品，并提供添加商品和移除商品的按钮。

public class MainActivity extends AppCompatActivity {
    private List<Product> productList = new ArrayList<>();
    private ShoppingCart shoppingCart = new ShoppingCart();
    private ProductAdapter productAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // 初始化商品列表
        productList.add(new Product("商品1", 10.0, 1));
        productList.add(new Product("商品2", 20.0, 1));
        productList.add(new Product("商品3", 30.0, 1));

        // 初始化购物车
        shoppingCart.addProduct(productList.get(0));

        // 设置商品列表适配器
        productAdapter = new ProductAdapter(this, productList);
        ListView listView = findViewById(R.id.list_view);
        listView.setAdapter(productAdapter);

        // 设置添加商品按钮的点击事件
        Button addButton = findViewById(R.id.add_button);
        addButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int position = (int) v.getTag();
                Product product = productList.get(position);
                shoppingCart.addProduct(product);
                productAdapter.notifyDataSetChanged();
            }
        });

        // 设置移除商品按钮的点击事件
        Button removeButton = findViewById(R.id.remove_button);
        removeButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int position = (int) v.getTag();
                Product product = productList.get(position);
                shoppingCart.removeProduct(product);
                productAdapter.notifyDataSetChanged();
            }
        });
    }

    // 商品列表适配器
    private class ProductAdapter extends BaseAdapter {
        private Context context;
        private List<Product> productList;

        public ProductAdapter(Context context, List<Product> productList) {
            this.context = context;
            this.productList = productList;
        }

        @Override
        public int getCount() {
            return productList.size();
        }

        @Override
        public Object getItem(int position) {
            return productList.get(position);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            if (convertView == null) {
                convertView = LayoutInflater.from(context).inflate(R.layout.product_item, parent, false);
            }

            Product product = productList.get(position);

            TextView nameTextView = convertView.findViewById(R.id.name_text_view);
            nameTextView.setText(product.getName());

            TextView priceTextView = convertView.findViewById(R.id.price_text_view);
            priceTextView.setText(String.format(Locale.getDefault(), "￥%.2f", product.getPrice()));

            TextView quantityTextView = convertView.findViewById(R.id.quantity_text_view);
            quantityTextView.setText(String.valueOf(product.getQuantity()));

            Button addButton = convertView.findViewById(R.id.add_button);
            addButton.setTag(position);

            Button removeButton = convertView.findViewById(R.id.remove_button);
            removeButton.setTag(position);

            return convertView;
        }
    }
}

4. 在购物车界面中显示购物车中的商品和总价。

public class ShoppingCartActivity extends AppCompatActivity {
    private ShoppingCart shoppingCart;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_shopping_cart);

        // 获取购物车对象
        shoppingCart = ((MyApplication) getApplication()).getShoppingCart();

        // 设置购物车列表适配器
        ListView listView = findViewById(R.id.list_view);
        listView.setAdapter(new ProductAdapter(shoppingCart.getProductList()));

        // 设置总价文本框
        TextView totalPriceTextView = findViewById(R.id.total_price_text_view);
        totalPriceTextView.setText(String.format(Locale.getDefault(), "总价：￥%.2f", shoppingCart.getTotalPrice()));
    }

    // 商品列表适配器
    private class ProductAdapter extends BaseAdapter {
        private List<Product> productList;

        public ProductAdapter(List<Product> productList) {
            this.productList = productList;
        }

        @Override
        public int getCount() {
            return productList.size();
        }

        @Override
        public Object getItem(int position) {
            return productList.get(position);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            if (convertView == null) {
                convertView = LayoutInflater.from(ShoppingCartActivity.this).inflate(R.layout.product_item, parent, false);
            }

            Product product = productList.get(position);

            TextView nameTextView = convertView.findViewById(R.id.name_text_view);
            nameTextView.setText(product.getName());

            TextView priceTextView = convertView.findViewById(R.id.price_text_view);
            priceTextView.setText(String.format(Locale.getDefault(), "￥%.2f", product.getPrice()));

            TextView quantityTextView = convertView.findViewById(R.id.quantity_text_view);
            quantityTextView.setText(String.valueOf(product.getQuantity()));

            return convertView;
        }
    }
}