Android ListView添加了太多项目

Question

我目前正在使用for循环在ListView元素内的LinearLayout中添加TextViews，因为我必须添加的TextViews数量是变量。我像往常一样将项目添加到ListViews。 问题是，当我滚动项目开始变得越来越多，当我向上滚动时，我最终得到了数百个项目。我认为这是因为ListView再次重新加载并循环遍历for循环，因此多次添加每个TextView。我可以阻止吗？

我的代码：

public class ListViewAdapter extends ArrayAdapter<RowItem> {

    private final Context context;

    public ListViewAdapter(Context context, List<RowItem> items) {
        super(context,  R.layout.list, items);
        this.context = context;
    }

    private class ViewHolder {
        TextView title;
        LinearLayout linearLayout;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        RowItem rowItem = getItem(position);

        LayoutInflater mInflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);

        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.list_list, null);
            holder = new ViewHolder();
            holder.title = (TextView) convertView.findViewById(R.id.list_line);
            holder.linearLayout = (LinearLayout) convertView.findViewById(R.id.list_linear);
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        holder.title.setText(rowItem.getTitle());

            String data = rowItem.getData();
            String[] split0 = data.split("=");

            Log.e("DATA", data);
            Log.e("LINE", rowItem.getTitle());

            for (int j = 0; j < split0.length; j++) {
                String[] split1 = split0[j].split(":");

                LinearLayout parentLayout = new LinearLayout(MainActivity.context);
                parentLayout.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT));
                parentLayout.setOrientation(LinearLayout.HORIZONTAL);

                for (int k = 0; k < split1.length; k++) {
                    TextView textView = new TextView(MainActivity.context);
                    textView.setText(split1[k]);
                    textView.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT, 1.0f));
                    textView.setGravity(Gravity.CENTER_HORIZONTAL | Gravity.CENTER_VERTICAL);
                    textView.setTextSize(18);

                    parentLayout.addView(textView);
                }
                holder.linearLayout.addView(parentLayout);
        }

        return convertView;
    }
}

我的数据情景对于一个条目看起来像这样：

text1:text2=text3:text4

它在列表中的显示方式：

text1    text2
text3    text4

Answer 1

问题是每次行可见时，ArrayAdapter都会调用getView()。如果之前已设置该行，则会传递convertView参数中先前设置的视图。

有关详细信息，请参阅here。来自convertView的{​​{1}}：

  

如果可能的话，重用旧视图。注意：你应该检查一下   在使用之前，view是非null且具有适当的类型。如果不是   可以转换此视图以显示正确的数据，此方法   可以创建一个新视图。异类列表可以指定它们的数量   视图类型，以便此视图始终是正确的类型（请参阅   getViewTypeCount（）和getItemViewType（int））。

编辑：由于提出的原始代码导致了问题，看起来您可能无法使用标准视图持有者设计模式。您有一个独特的设置，您可以在其中创建每行中的动态数量的项目。

您可能可以执行略微优化的操作，您无需在每次inflate()来电时致电getView()，但每次都会重新创建ViewHolder调用getView()，以便在滚动时填充正确的数据：

public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder;
    RowItem rowItem = getItem(position);

    LayoutInflater mInflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);

    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.list_list, null);

    } 

    holder = new ViewHolder();
    holder.title = (TextView) convertView.findViewById(R.id.list_line);
    holder.linearLayout = (LinearLayout) convertView.findViewById(R.id.list_linear);
    convertView.setTag(holder);


    holder.title.setText(rowItem.getTitle());

        String data = rowItem.getData();
        String[] split0 = data.split("=");

        Log.e("DATA", data);
        Log.e("LINE", rowItem.getTitle());

        for (int j = 0; j < split0.length; j++) {
            String[] split1 = split0[j].split(":");

            LinearLayout parentLayout = new LinearLayout(MainActivity.context);
            parentLayout.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT));
            parentLayout.setOrientation(LinearLayout.HORIZONTAL);

            for (int k = 0; k < split1.length; k++) {
                TextView textView = new TextView(MainActivity.context);
                textView.setText(split1[k]);
                textView.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT, 1.0f));
                textView.setGravity(Gravity.CENTER_HORIZONTAL | Gravity.CENTER_VERTICAL);
                textView.setTextSize(18);

                parentLayout.addView(textView);
            }
            holder.linearLayout.addView(parentLayout);
        }


    return convertView;
}

如果这不起作用，您可以回到基础，只需在每次调用getView()时完全重新创建视图：

public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        RowItem rowItem = getItem(position);

        LayoutInflater mInflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);

        //if (convertView == null) {
            convertView = mInflater.inflate(R.layout.list_list, null);
            holder = new ViewHolder();
            holder.title = (TextView) convertView.findViewById(R.id.list_line);
            holder.linearLayout = (LinearLayout) convertView.findViewById(R.id.list_linear);
            convertView.setTag(holder);

            holder.title.setText(rowItem.getTitle());

            String data = rowItem.getData();
            String[] split0 = data.split("=");

            Log.e("DATA", data);
            Log.e("LINE", rowItem.getTitle());

            for (int j = 0; j < split0.length; j++) {
                String[] split1 = split0[j].split(":");

                LinearLayout parentLayout = new LinearLayout(MainActivity.context);
                parentLayout.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT));
                parentLayout.setOrientation(LinearLayout.HORIZONTAL);

                for (int k = 0; k < split1.length; k++) {
                    TextView textView = new TextView(MainActivity.context);
                    textView.setText(split1[k]);
                    textView.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT, 1.0f));
                    textView.setGravity(Gravity.CENTER_HORIZONTAL | Gravity.CENTER_VERTICAL);
                    textView.setTextSize(18);

                    parentLayout.addView(textView);
                }
                holder.linearLayout.addView(parentLayout);
            }     

        //} 

        return convertView;
    }