Question

我的仪表板活动中有textview txtQuantity。我为自定义适配器编写了单独的类，其中包含已售出的产品。

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_dashboard);

    list = (ListView) findViewById(R.id.listSoldItems);

    txtAmount = (TextView) findViewById(R.id.txtAmount);
    txtItems = (TextView) findViewById(R.id.txtItems);

    // init listview
    adapter = new Sold_item_adaptor(Dashboard.this, soldItemsList);
    list.setAdapter(adapter);

我可以使用适配器从列表中删除项目。删除项的代码用适配器类编写。

public View getView(final int position, View convertView, ViewGroup parent) {
    View vi = convertView;
    if (convertView == null)
        vi = inflater.inflate(R.layout.list_row_sold_item, null);

    TextView txtListItem = (TextView) vi.findViewById(R.id.txtListItem);
    final TextView txtQuantity = (TextView) vi.findViewById(R.id.txtQuantity);
    ImageView imgCancel = (ImageView) vi.findViewById(R.id.imgCancel);

    HashMap<String, String> mapData = new HashMap<String, String>();
    mapData = data.get(position);

    txtListItem.setText(mapData.get("product"));
    txtQuantity.setText(mapData.get("qty"));

    imgCancel.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            doButtonOneClickActions(txtQuantity, position);
        }
    });

    return vi;
}

private void doButtonOneClickActions(TextView txtQuantity, int rowNumber) {
    // Do the actions for Button one in row rowNumber (starts at zero)
    data.remove(rowNumber);
    notifyDataSetChanged();

}

在我的信息中心活动中，我维护所选项目的数量，总金额。现在，如果我从listview中删除项目，自定义适配器中的代码将删除该项目，但如何在仪表板活动上获取通知/信号以更新数量。

Answer 1

提供简单的回调。

为此，请在适配器中编写一个简单的界面

public interface OnDataChangeListener{
    public void onDataChanged(int size);
}

并为侦听器（也在适配器中）添加一个setter

OnDataChangeListener mOnDataChangeListener;
public void setOnDataChangeListener(OnDataChangeListener onDataChangeListener){
    mOnDataChangeListener = onDataChangeListener;
}

现在将其他代码添加到适配器中的以下块

private void doButtonOneClickActions(TextView txtQuantity, int rowNumber) {
    ...
    if(mOnDataChangeListener != null){
        mOnDataChangeListener.onDataChanged(data.size());
    }
}

在仪表板活动中，您需要注册监听器

protected void onCreate(Bundle savedInstanceState) {
    ...
    adapter.setOnDataChangeListener(new Sold_item_adaptor.OnDataChangeListener(){
        public void onDataChanged(int size){
            //do whatever here
        }
    });
}

就是这样;）。

Answer 2

主要思想是：

protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dashboard);

list = (ListView) findViewById(R.id.listSoldItems);

txtAmount = (TextView) findViewById(R.id.txtAmount);
txtItems = (TextView) findViewById(R.id.txtItems);

// init listview
adapter = new Sold_item_adaptor(Dashboard.this, soldItemsList,txtAmount);
list.setAdapter(adapter);

适配器中的

：

public class MyAdapter extends ArrayAdapter<SoldItemsList > {

private Context context;
private mTotalQty;
private TextView mTxtAmountAdapter;


 public OfferAdapter(Context context, int resource,SoldItemsList object,TextView txtAmount ) {
    super(context, resource, objects);
    this.context = context;
    this.mTxtAmountAdapter = txtAmount;


}

//...

imgCancel.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
    doButtonOneClickActions(position);
    // update totalAmount
     mTxtAmountAdapter.setText(Integer.valueOf(totalAmount).toString()));

}
});

imgPlus.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
    qtyClickAction(position);
     // update totalQty
    mTxtAmountAdapter.setText(Integer.valueOf(totalAmount).toString()));

}
});

Answer 3

覆盖适配器类中的notifyDataSetChanged（）...并按照您的意愿执行...

@Override
public void notifyDataSetChanged() {
    super.notifyDataSetChanged();
   // Your code to nofify
}

Answer 4

据我所知，您对doButtonOneClickActions（）之后更新适配器外部的UI感兴趣;

最简单的方法是使用https://github.com/greenrobot/EventBus

可在此处找到示例http://awalkingcity.com/blog/2013/02/26/productive-android-eventbus/

如果您不想这样做，可以创建回调http://android-er.blogspot.dk/2013/09/implement-callback-function-with.html

更改适配器类中的数据后，更新活动上的textview

4 个答案: