Question

大家好我正在使用自定义列表视图从服务器获取数据并在listview中显示..我能够获取数据并在listview中显示它但我不知道在listitem中实现按钮的click事件。有两个按钮来递增和递减数量。我的clicklistener正在工作，但它没有以正确的方式工作。请帮我纠正这个问题。我在堆栈溢出中搜索了太多的帖子但是无法理解它...

这是我的适配器类

    private Activity activity;
private LayoutInflater inflater;
private List<FeedItem> feedItems;
private List<FeedItem> filteredfeedItems;
ImageView plus;
ImageView minus;
int qty = 0;

String result;
String formattedDate;
int id;



public FeedListAdapter(Activity activity, List<FeedItem> feedItems) {
    this.activity = activity;
    this.feedItems = feedItems;
    this.filteredfeedItems = feedItems;
}

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

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

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

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    if (inflater == null)
        inflater = (LayoutInflater) activity
        .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    if (convertView == null)
        convertView = inflater.inflate(R.layout.feed_item, null);

    FeedItem item = filteredfeedItems.get(position);

    id = item.getId();
    convertView.setTag(Integer.valueOf(id));

    TextView date = (TextView) convertView.findViewById(R.id.name);
    TextView initiator = (TextView) convertView
            .findViewById(R.id.timestamp4);
    TextView assignTo = (TextView) convertView.findViewById(R.id.timestamp);

    final TextView location = (TextView) convertView.findViewById(R.id.timestamp2);

    //TextView category = (TextView) convertView.findViewById(R.id.category);


    data.setText(item.getData();
    price
    .setText(item.getPrice());
    description.setText(item.getDescription());


     plus = (ImageView) convertView.findViewById(R.id.btnAddToCart1);
      plus.setTag(item.getId());
    plus.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            int position = (Integer) view.getTag();


            //convertView.setTag(Integer.valueOf(id));
            FeedItem item = filteredfeedItems.get(position);
            item.quantity++;
            location.setText(String.valueOf(item.quantity));

        }
    });


     minus = (ImageView) convertView.findViewById(R.id.btnAddToCart5);
    minus.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {

             Integer taggedPosition = (Integer) view.getTag();
    if (qty>0){
        //minus.setImageResource(R.drawable.minus_pressed);
            qty--;
            location.setText(String.valueOf(qty));
    }

    else{

        qty = 0;
    }
        }
    });

    return convertView;
}

这是我的FeedItem类：

public class FeedItem {

 int quantity = 0;
 int id;


public FeedItem(int id,int quantity){
    super();
    this.id = id;
    this.quantity = quantity;

}

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}



 public int getQuantity() {
        return quantity;
    }

    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }

Answer 1

目前，每个活动有1个变量来存储数量。如果您希望按项目存储，则应添加：int qty;以成为FeedItem类中的成员。

卸下：

convertView.setTag(Integer.valueOf(id));

和plus类似，您需要添加：

minus.setTag(item.getId());

然后代替qty++;或基本上在onClick中的每个位置而不是qty，您需要使用item.qty：

Integer id = view.getTag();
FeedItem item = filteredfeedItems.get(id);
item.qty++;
location.setText(String.valueOf(item.qty));

更新

我认为你将FeedItem.id与位置混合在一起。如果您没有更改列表中的项目顺序/数量，那么您可以始终使用位置。而不是：

minus.setTag(item.getId());

尝试：

minus.setTag(position);

和plus

相同

Answer 2

最后我解决了我自己的回答。只需要在片段类中实现接口和调用..

更新了适配器类

public class FeedListAdapter extends RecyclerView.Adapter<FeedListAdapter.ViewHolder> {
private Activity activity;
private LayoutInflater inflater;
private List<FeedItem> feedItems;
private List<FeedItem> filteredfeedItems;
ImageView plus;
ImageView minus;
String result;
String formattedDate;
int id;
 private View.OnClickListener onAddNum;
 private View.OnClickListener onSubNum;

public FeedListAdapter(Activity activity, List<FeedItem> feedItems)
{       this.activity = activity;
    this.feedItems = feedItems;
    this.filteredfeedItems = feedItems;

    inflater = ( LayoutInflater )activity.
            getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

// create interface method

  public void setOnAddNum(View.OnClickListener onAddNum){ 
        this.onAddNum = onAddNum;
    }
    public void setOnSubNum(View.OnClickListener onSubNum){
        this.onSubNum = onSubNum;
    }

  @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.feed_item, parent, false);
        ViewHolder viewHolder = new ViewHolder(v);
        return viewHolder;
    }
  @Override
    public void onBindViewHolder(final ViewHolder holder, int position) {

      FeedItem item =(FeedItem)filteredfeedItems.get(position);
         holder.date.setText(item.getObservation());
         holder.initiator
            .setText(item.getObservation());
            holder.location.setText(String.valueOf(item.getNum())+"");
         holder.assignTo.setText(item.getSummary());

 // set tag to know which button you clicked'

         holder.plus.setTag(position);
         holder.plus.setFocusable(true);
         holder.plus.setClickable(true);

 //  set callback interface  ，  

         holder.plus.setOnClickListener(onAddNum);
         holder.minus.setTag(position);
         holder.minus.setOnClickListener(onSubNum);

  }
  @Override
    public int getItemCount() {
        return filteredfeedItems.size();
    }

  public long getItemId(int position) {
    return position;

  }

    class ViewHolder extends RecyclerView.ViewHolder{

         ImageView plus;
         ImageView minus;
         TextView date;
         TextView initiator;
         TextView assignTo;
         TextView location;
        public ViewHolder(View vi) {
            super(vi);

           date = (TextView) vi.findViewById(R.id.name);
           initiator = (TextView) vi
                    .findViewById(R.id.timestamp4);
           assignTo = (TextView) vi.findViewById(R.id.timestamp);

           location = (TextView) vi.findViewById(R.id.timestamp2);
           plus = (ImageView) vi.findViewById(R.id.btnAddToCart1);

           minus = (ImageView) vi.findViewById(R.id.btnAddToCart5);

        }
    }
}

现在在activity类中为按钮事件实现View.OnClickListener。

public class MyFragment extends Fragment implements View.OnClickListener

 @Override
public void onClick(View view) {
    Object tag = view.getTag();
    switch (view.getId()){
        case R.id.item_btn_add: //  click add buttons number  ，  performs corresponding processing  

 if (tag != null && tag instanceof Integer) {

                 int position = (Integer) tag;
            Your pojo class  

      int num =feedItems.get(position).getNum();
         num++;
      feedItems.get(position).setNum(num);
       adapter.notifyDataSetChanged();
  }
     break;

   case R.id.btnAddToCart5:
       if (tag != null && tag instanceof Integer) {

           int position = (Integer) tag;
           int num =feedItems.get(position).getNum();

       if (num>0) {
           num--;
           feedItems.get(position).setNum(num);
           listAdapter.notifyDataSetChanged();
       }

       else{
            num= 0;
            listAdapter.notifyDataSetChanged();
        }

       }
       break;
     }

享受编码

Answer 3

像这样创建一个MyListItem类：

public class MyListItem{

private int qty;
private int itemId;
public void setQty(int qty)
{
this.qty=qty;

}
public void setQty(int qty)
{
this.qty=qty;

}
public int getItemId()
{
return this.itemId;
}
public int getQty()
{
return this.qty;
}
public MyListItem(int qty,int itemId)
{
this.qty=qty;
this.itemId=itemId;

}
}

加载项目时，将所有项目初始化为 MyListItem 。

您的监听器应该更改对象的数量值。现在制作一个MyListItem 不是阵列的数组列表，因为您不知道当时有多少项目

希望这个帮助

Android - 无法从列表项增加或减少值

3 个答案: