Question

我尝试在两个活动之间传输数据，然后使用适配器显示。之前我使用相同的适配器来显示List，但这会在我的适配器中出现几个错误，并且我已在下面的代码中显示它们。

任何人都可以知道我应该怎么做才能纠正它。任何帮助将不胜感激。

第一项活动传递了这些细节，

                                intent.putExtra("quantity", quantity);
                                intent.putExtra("instructions", instructions);
                                intent.putExtra("subTotal", subTotal);
                                intent.putExtra("description", description);
                                intent.putExtra("price", price);

第二项活动

        String quantity = getIntent().getStringExtra("quantity");
        String description = getIntent().getStringExtra("description");
        String subTotal = getIntent().getStringExtra("subTotal");
        String price = getIntent().getStringExtra("price");

        CustomGridPastaCart adapter = new CustomGridPastaCart(getApplicationContext(),
                quantity, description, subTotal, price); //error2

CustomGridPastaCart，BaseAdapter

public class CustomGridPastaCart extends BaseAdapter {
private Context context;
List<Item> items;

public CustomGridPastaCart(Context c, List<Item> items) {
    this.items = items;
}

public CustomGridPastaCart(Context applicationContext, String quantity, //it was forcing me to generate this error2 in above
        String description, String subTotal, String price) {
    // TODO Auto-generated constructor stub
}

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

@Override
public Item getItem(int position) { //here i had to change object to Item because it gave an error1 in below
    return items.get(position);
}

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

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder;
    if (convertView == null) {
        holder = new ViewHolder();
        convertView = LayoutInflater.from(context).inflate(
            R.layout.cart_activity, parent, false);
        holder.tvHeader = (TextView) convertView
            .findViewById(R.id.lblListHeader);
        holder.tvUnitprice = (TextView) convertView
            .findViewById(R.id.lbl_unitprice);
        holder.tvQty = (TextView) convertView.findViewById(R.id.lbl_qty);
        holder.ivSubtotal = (TextView) convertView
            .findViewById(R.id.lblsubtotal);
        convertView.setTag(holder);

    } else {
        holder = (ViewHolder) convertView.getTag();
    }

    // Get item...
    Item item = getItem(position); //error1 here

    // Set values.
    holder.tvHeader.setText(item.description);
    holder.tvUnitprice.setText(item.price);
    holder.tvQty.setText(item.quantity);
    holder.ivSubtotal.setText(item.subTotal);

    return convertView;
}

private class ViewHolder {
   private TextView tvHeader;
   private TextView tvUnitprice;
   private TextView tvQty;
   private TextView ivSubtotal;

} }

Item.java

public class Item {
    String quantity;
    String description;
    String subTotal;
    String price;
}

enter image description here

Answer 1

您使用的适配器错误。 ListView需要一个Adapter，它基本上是一个包含列表（或数组）的结构，以及处理它并创建表示每个项目的视图的方法。

您正在传递单个项目的字段，因此description是一个字符串，因此失败：

@Override
public int getCount() {
    return description.size(); //The method size() is undefined for the type String
}

getItem

存在同样的问题

@Override
public Object getItem(int position) { 
    return description.get(position); //The method get(int) is undefined for the type String
}

你需要为你的适配器实现这样的东西：

public class CustomGridPastaCart extends BaseAdapter {
    private Context context;
    List<Item> items;

    public CustomGridPastaCart(Context c, List<Item> items) {
        this.items = items;
    }

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

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

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            holder = new ViewHolder();
            convertView = LayoutInflater.from(context).inflate(
                R.layout.cart_activity, parent, false);
            holder.tvHeader = (TextView) convertView
                .findViewById(R.id.lblListHeader);
            holder.tvUnitprice = (TextView) convertView
                .findViewById(R.id.lbl_unitprice);
            holder.tvQty = (TextView) convertView.findViewById(R.id.lbl_qty);
            holder.ivSubtotal = (TextView) convertView
                .findViewById(R.id.lblsubtotal);
            convertView.setTag(holder);

        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        // Get item...
        Item item = getItem(position);

        // Set values.
        holder.tvHeader.setText(item.description);
        holder.tvUnitprice.setText(item.price);
        holder.tvQty.setText(item.quantity);
        holder.ivSubtotal.setText(String.valueOf(item.subTotal));

        return convertView;
    }

    private class ViewHolder {
       private TextView tvHeader;
       private TextView tvUnitprice;
       private TextView tvQty;
       private TextView ivSubtotal;
   }
}

和Item类：

public class Item {
    String quantity;
    String description;
    double subTotal;
    String price;
}

测试：

String quantity = getIntent().getStringExtra("quantity");
String description = getIntent().getStringExtra("description");
String subTotal = getIntent().getStringExtra("subTotal");
String price = getIntent().getStringExtra("price");

Item item = new Item();
item.quantity = quantity;
item.description = description;
item.subTotal = subTotal;
item.price = price;

ArrayList<Item> list = new ArrayList<Item>();
list.add(item);

CustomGridPastaCart adapter = new CustomGridPastaCart(getApplicationContext(), list);

使用适配器将项目加载到可扩展列表视图

1 个答案: