. 购物车页面可实现商品数量的增减、商品的删除以及总价格计算功能。用Android实现写出代码

好的，以下是一个简单的购物车页面的实现代码：

布局文件 cart_layout.xml：

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ListView
        android:id="@+id/cart_list"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

    <TextView
        android:id="@+id/total_price"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="总价格：0元" />

    <Button
        android:id="@+id/checkout_btn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="结算" />

</LinearLayout>

Java代码：

public class CartActivity extends AppCompatActivity {

    private ListView cartList;
    private TextView totalPrice;
    private Button checkoutBtn;

    private List<CartItem> itemList = new ArrayList<>();
    private CartAdapter adapter;

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

        cartList = findViewById(R.id.cart_list);
        totalPrice = findViewById(R.id.total_price);
        checkoutBtn = findViewById(R.id.checkout_btn);

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

        adapter = new CartAdapter(this, itemList);
        cartList.setAdapter(adapter);

        // 计算总价格
        double total = 0.0;
        for (CartItem item : itemList) {
            total += item.getPrice() * item.getNum();
        }
        totalPrice.setText("总价格：" + total + "元");

        // 增减商品数量
        adapter.setOnNumChangeListener(new CartAdapter.OnNumChangeListener() {
            @Override
            public void onNumChange(int position, int num) {
                itemList.get(position).setNum(num);
                adapter.notifyDataSetChanged();

                // 重新计算总价格
                double total = 0.0;
                for (CartItem item : itemList) {
                    total += item.getPrice() * item.getNum();
                }
                totalPrice.setText("总价格：" + total + "元");
            }
        });

        // 删除商品
        adapter.setOnDeleteListener(new CartAdapter.OnDeleteListener() {
            @Override
            public void onDelete(int position) {
                itemList.remove(position);
                adapter.notifyDataSetChanged();

                // 重新计算总价格
                double total = 0.0;
                for (CartItem item : itemList) {
                    total += item.getPrice() * item.getNum();
                }
                totalPrice.setText("总价格：" + total + "元");
            }
        });

        // 结算
        checkoutBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO: 进行结算操作
            }
        });
    }
}

class CartAdapter extends BaseAdapter {

    private Context context;
    private List<CartItem> itemList;
    private LayoutInflater inflater;

    // 商品数量变化监听器
    private OnNumChangeListener onNumChangeListener;

    // 商品删除监听器
    private OnDeleteListener onDeleteListener;

    public CartAdapter(Context context, List<CartItem> itemList) {
        this.context = context;
        this.itemList = itemList;
        inflater = LayoutInflater.from(context);
    }

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

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

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

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.cart_item_layout, null);
            holder = new ViewHolder();
            holder.name = convertView.findViewById(R.id.item_name);
            holder.price = convertView.findViewById(R.id.item_price);
            holder.num = convertView.findViewById(R.id.item_num);
            holder.addBtn = convertView.findViewById(R.id.add_btn);
            holder.minusBtn = convertView.findViewById(R.id.minus_btn);
            holder.deleteBtn = convertView.findViewById(R.id.delete_btn);
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        final CartItem item = itemList.get(position);

        holder.name.setText(item.getName());
        holder.price.setText("单价：" + item.getPrice() + "元");
        holder.num.setText(item.getNum() + "");

        holder.addBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int num = item.getNum() + 1;
                item.setNum(num);
                notifyDataSetChanged();
                if (onNumChangeListener != null) {
                    onNumChangeListener.onNumChange(position, num);
                }
            }
        });

        holder.minusBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int num = item.getNum() - 1;
                if (num < 1) {
                    num = 1;
                }
                item.setNum(num);
                notifyDataSetChanged();
                if (onNumChangeListener != null) {
                    onNumChangeListener.onNumChange(position, num);
                }
            }
        });

        holder.deleteBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (onDeleteListener != null) {
                    onDeleteListener.onDelete(position);
                }
            }
        });

        return convertView;
    }

    public void setOnNumChangeListener(OnNumChangeListener listener) {
        this.onNumChangeListener = listener;
    }

    public void setOnDeleteListener(OnDeleteListener listener) {
        this.onDeleteListener = listener;
    }

    interface OnNumChangeListener {
        void onNumChange(int position, int num);
    }

    interface OnDeleteListener {
        void onDelete(int position);
    }

    static class ViewHolder {
        TextView name;
        TextView price;
        TextView num;
        Button addBtn;
        Button minusBtn;
        Button deleteBtn;
    }
}

class CartItem {

    private String name;
    private double price;
    private int num;

    public CartItem(String name, double price, int num) {
        this.name = name;
        this.price = price;
        this.num = num;
    }

    public String getName() {
        return name;
    }

    public double getPrice() {
        return price;
    }

    public int getNum() {
        return num;
    }

    public void setNum(int num) {
        this.num = num;
    }
}

这个购物车页面实现了商品数量的增减、商品的删除以及总价格计算功能。购物车中的商品列表使用 ListView 控件展示，每个商品项中包含商品名称、单价、数量、增加数量按钮、减少数量按钮和删除按钮。购物车页面的总价格通过计算所有商品的数量和单价得出。购物车页面的结算按钮还未实现具体的结算操作，需要根据实际情况进行编写。