1

我正在尝试编写一个 ListView 适配器，它将基于几个 xml 文件之一传递一个视图，具体取决于我为其创建视图的数据的属性。我的代码工作正常，除非我尝试使用 convertView 来加快进程。无论我如何尝试使用它，我要么崩溃我的程序，要么得到奇怪的输出。我理解为什么这对 convertView 来说是个问题，但我强烈怀疑我仍然可以完成这项工作。谁能告诉我如何修复我的代码？（现在我使用 convertView 作为我返回的视图的名称，即使我没有 'if (convertView==null)' 例程正常工作）

public class PaymentListFragment extends ListFragment {

private ArrayList<Payment> mPayments;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getActivity().setTitle(R.string.payment_schedule_title);
    mPayments = PaymentSchedule.get(getActivity()).getPayments();
    PaymentAdapter adapter = new PaymentAdapter(mPayments);
    setListAdapter(adapter);
}


private class PaymentAdapter extends ArrayAdapter<Payment> {

    public PaymentAdapter(ArrayList<Payment> payments) {
        super(getActivity(), 0, payments);
    }

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

        Payment p = mPayments.get(position);
        //normal
        //if (convertView == null) {
        //cant work out how to use convertview conditional without screwing up project
        //it would speed it up to fix this however
        if (p.type == Payment.TYPE_START) {


            convertView = getActivity().getLayoutInflater().inflate(R.layout.list_item_start, null);

            TextView remainDisplay =
                    (TextView) convertView.findViewById(R.id.remainDisplayStart);
            remainDisplay.setText(p.getRemainString());
            TextView paymentDate =
                    (TextView) convertView.findViewById(R.id.paymentDateStart);
            paymentDate.setText(p.getDateString());
            TextView paymentDisplay =
                    (TextView) convertView.findViewById(R.id.paymentDisplayStart);
            paymentDisplay.setText(p.getDefaultPaymentString());
            TextView aprDisplay =
                    (TextView) convertView.findViewById(R.id.aprDisplayStart);
            aprDisplay.setText(p.getInterestRate() * 1200 + "%");
        } else {
             //if (convertView == null) {
                convertView = getActivity().getLayoutInflater().inflate(R.layout.list_item_payment, null);
            //}
            TextView paymentDate =
                    (TextView) convertView.findViewById(R.id.paymentDate);
            paymentDate.setText(p.getDateString());
            TextView paymentDisplay =
                    (TextView) convertView.findViewById(R.id.paymentDisplay);
            paymentDisplay.setText(p.getPaymentString());
            TextView principalDisplay =
                    (TextView) convertView.findViewById(R.id.principalDisplay);
            principalDisplay.setText(p.getPrincipalString());
            TextView interestDisplay =
                    (TextView) convertView.findViewById(R.id.interestDisplay);
            interestDisplay.setText(p.getInterestString());
            TextView remainDisplay =
                    (TextView) convertView.findViewById(R.id.remainDisplay);
            remainDisplay.setText(p.getRemainString());
        }
        //}
        return convertView;
    }
}
}
4

3 回答 3

3

您可以执行以下技巧：

  1. 创建时始终为您附加一个标签convertView（setTag()），指定布局的类型（在您的情况下R.layout.list_item_start或R.layout.list_item_payment）。

  2. 当您检查是否convertView != null还需要检查 指定的类型convertView.getTag()是否与您正在更新的布局相同以避免正确膨胀操作时，因为：

    • 如果类型不同，您需要convertView使用新的膨胀操作覆盖，因为您需要创建正确的布局类型。
    • 如果类型相同，您可以简单地更新布局而无需充气操作

您还可以通过采用ViewHolder 模式来改进整个代码。

于 2015-02-17T18:25:33.053 回答
1

谢谢！Bonnyz 的建议奏效了。我添加了以下代码：

Payment p = mPayments.get(position);

        if (convertView == null || convertView.getTag() != p.type) {
            if(p.type == Payment.TYPE_START) {
                convertView = getActivity().getLayoutInflater().inflate(R.layout.list_item_start, null);
                convertView.setTag(Payment.TYPE_START);
            } else{
                convertView = getActivity().getLayoutInflater().inflate(R.layout.list_item_payment, null);
                convertView.setTag(Payment.TYPE_PAYMENT);
            }

        }

我也将尝试使用 ViewHolder。我今天才知道这一点。

于 2015-02-17T19:46:00.457 回答
0 
public class CustomAdapter extends BaseAdapter {
String[] frName;
String[] lrName;
String[] myLocation;
Context context;
int[] imageId;
private static LayoutInflater inflater = null;


public CustomAdapter(MainActivity mainActivity, String[] fstName, String[] lstName, String[] location, int[] prgmImages) {
    super();
    context = mainActivity;
    frName = fstName;
    lrName = lstName;
    myLocation = location;
    imageId = prgmImages;
    inflater = (LayoutInflater) context.
            getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}


@Override
public int getCount() {
    // TODO Auto-generated method stub
    return 12;

}

@Override
public Object getItem(int position) {
    // TODO Auto-generated method stub
    return position;
}

@Override
public long getItemId(int position) {
    // TODO Auto-generated method stub
    return position;
}

public class Holder {
    TextView tv_frname, tv_lrname, tv_location, tv_fstname, tv_lstname;
    ImageView img;

}

@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    Holder holder = new Holder();
    if (position < frName.length) {
        convertView = inflater.inflate(R.layout.myadapterdesin, null);
        holder.tv_frname = (TextView) convertView.findViewById(R.id.frname);
        holder.tv_lrname = (TextView) convertView.findViewById(R.id.lrname);
        holder.tv_location = (TextView) convertView.findViewById(R.id.place);
        holder.tv_frname.setText(frName[position]);
        holder.tv_lrname.setText(lrName[position]);
        holder.tv_location.setText(myLocation[position]);
        convertView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                Toast.makeText(context, "You Clicked " + position, Toast.LENGTH_SHORT).show();
            }
        });
        return convertView;

    } else if (position >= frName.length) {
        convertView = inflater.inflate(R.layout.mylist, null);
        holder.img = (ImageView) convertView.findViewById(R.id.img_view);
        holder.tv_fstname = (TextView) convertView.findViewById(R.id.fstname);
        holder.tv_lstname = (TextView) convertView.findViewById(R.id.lstname);
        holder.tv_fstname.setText(frName[(position) - (frName.length)]);
        holder.tv_lstname.setText(lrName[(position) - (frName.length)]);
        holder.img.setImageResource(imageId[(position) - (frName.length)]);

        convertView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                Toast.makeText(context, "You Clicked " + position, Toast.LENGTH_SHORT).show();
            }
        });
        return convertView;
    }
    convertView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Toast.makeText(context, "You Clicked " + position, Toast.LENGTH_SHORT).show();
        }
    });
    return convertView;

}

}

于 2016-05-10T12:11:53.740 回答