问题描述
我有一个Android的活动中，我有绑定到自定义ArrayAdapter一个ListView。 ListView中的每一行有两个EditText上（数字）的字段。
I have an Android activity in which I have a ListView bound to a custom ArrayAdapter. Each row of the ListView has two EditText (numeric) fields.
一个ArrayAdapter最初填充是从一个SQLite数据库。然而，用户可以（在连续被长期pressing）在ListView的，或者末尾添加一行删除ListView中的任何行。当他们点击保存按钮，其变动持续。
The ArrayAdapter is initially populated from an SQLite DB. However the user can add a row at the end of the ListView, or (by long-pressing on a row) delete any row in the ListView. When they hit the 'Save' button, their changes are persisted.
我保持轨道变化的，因为它们是通过附加一个CustomTextWatcher为AfterTextChanged（）事件的每个的EditText在一个ArrayAdapter的getView（）方法（传入的EditText和一个ArrayAdapter的项目列表中的相应对象）制成，然后该对象的匹配属性设置为的EditText的内容。这是为了让节约我可以简单地通过底层对象列表循环，并做出相应的DB的变化，知道该对象列表是最新的。
I am keeping track of changes as they are made by attaching a CustomTextWatcher for the AfterTextChanged() event to each EditText in the ArrayAdapter's getView() method (passing in the EditText and the corresponding object in the ArrayAdapter's item list) and then setting the matching property of that object to the content of the EditText. This is so that on saving I can simply iterate through the underlying object list and make the appropriate DB changes, knowing that the object list is up-to-date.
code适配器类和CustomTextWatcher：
Code for the adapter class and the CustomTextWatcher:
private class CustomAdapter extends ArrayAdapter<DataItem> {
private ArrayList<DataItem> items;
public CustomAdapter(Context context, int textViewResourceId, ArrayList<DataItem> items) {
super(context, textViewResourceId, items);
this.items = items;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
DataItem wed = items.get(position);
if (v == null) {
LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.log_exercise_row, null);
}
if(wed != null)
{
EditText text1 = (EditText) v.findViewById(R.id.text1);
EditText text2 = (EditText) v.findViewById(R.id.text2);
text1.addTextChangedListener(new CustomTextWatcher(text1,wed));
text2.addTextChangedListener(new CustomTextWatcher(text2,wed));
int weight = wed.getWeight();
if(weight != -1)
{
text1.setText(weight+"");
}
int reps = wed.getReps();
if(reps != -1)
{
text2.setText(reps+"");
}
}
return v;
}
private class CustomTextWatcher implements TextWatcher {
private EditText EditText;
private DataItem item;
public CustomTextWatcher(EditText e, DataItem item)
{
this.EditText = e;
this.item = item;
}
@Override
public void afterTextChanged(Editable arg0) {
String text = arg0.toString();
if(text != null && text.length() > 0)
{
int val;
try
{
val =Integer.parseInt(text);
}
catch(NumberFormatException e)
{
val=-1;
}
if(EditText.getId()==R.id.weightEditText)
{
item.setWeight(val);
}
else if(EditText.getId()==R.id.repsEditText)
{
item.setRepetitions(val);
}
}
}
这一切工作正常，当项目被添加或删除时的EditText内容的不必要的重复发生的除外。
This all works fine except when items are added or deleted when unwanted duplication of EditText content happens.
要说明一个例子：
开始用3行，EditText上的所有空
在第2行中，输入5，6
点击更多 - >将在年底的（空）行。现在，4行。
删除最后显示的行级别> 3行，但第2和第3行，现在显示5，6 - > ???????
Start with 3 rows, EditText's all empty
In row 2, enter '5', '6'
Click 'More'->Adds an (empty) row on the end. Now 4 rows.
Delete last row->3 rows displayed, BUT 2nd AND 3rd rows now display '5', '6'->???????
它看起来像的EditText对象的ListView控件中的相对位置不重新绑定，这是造成该问题后保持稳定。例如。的EditText对象X开头3位，再经过重新绑定在位置1 - 但它仍然有一个CustomTextWatcher连接到它引用的数据对象的位置3的另一个问题是，addTextChangedListener（）不影响所述TextWatchers已经连接到的EditText。
It looks like the relative position of EditText objects within the ListView is not stable after rebinding which is causing the problem. E.g. EditText object 'X' starts in position 3, then after a rebind it is in position 1 - but it still has a CustomTextWatcher attached to it referencing the data object in position 3. The other issue is the fact that addTextChangedListener() does not affect the TextWatchers already attached to the EditText.
我是pretty的新的Android，所以我不知道是否有更好的方法来解决我的问题。任何帮助是AP preciated。
I'm pretty new to Android, so I'm not sure if there is a better approach to solve my problem. Any help is appreciated.
推荐答案
它看起来像一个自定义（ViewHolder'）班是我需要的，以便保持的EditText及其关联的数据对象上每个正确同步间引用数据的绑定。此外，将事件侦听器调用时convertView对象是在getView（）方法返回null意味着只有一个监听器每个对象的EditText加入。
It looks like a custom ('ViewHolder') class was what I needed in order to keep the references between a EditText and its associated data object properly synchronised on each 'bind' of the data. Also, placing the event listener calls when the convertView object was null in the getView() method meant only one listener was added per EditText object.
感谢http://www.vogella.de/articles/AndroidListView/article.html#listsactivity指着我在正确的方向。
Thanks to http://www.vogella.de/articles/AndroidListView/article.html#listsactivity for pointing me in the right direction.
public class CustomAdapter extends ArrayAdapter<DataItem> {
private ArrayList<DataItem> items;
private Activity Context;
public CustomAdapter(Activity context, int textViewResourceId, ArrayList<DataItem> items) {
super(context, textViewResourceId, items);
this.items = items;
this.Context = context;
}
static class ViewHolder {
protected EditText weight;
protected EditText reps;
}
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
DataItem wed = items.get(position);
if (v == null) {
LayoutInflater inflator = Context.getLayoutInflater();
v = inflator.inflate(R.layout.log_exercise_row, null);
final ViewHolder viewHolder = new ViewHolder();
viewHolder.text1 = (EditText) v.findViewById(R.id.text1);
viewHolder.text2 = (EditText) v.findViewById(R.id.text2);
viewHolder.text1.addTextChangedListener(new CustomTextWatcher(viewHolder, viewHolder.text1));
viewHolder.text2.addTextChangedListener(new CustomTextWatcher(viewHolder, viewHolder.text2));
v.setTag(viewHolder);
viewHolder.text1.setTag(wed);
viewHolder.text2.setTag(wed);
}
else
{
ViewHolder holder = (ViewHolder) v.getTag();
holder.text1.setTag(wed);
holder.text2.setTag(wed);
}
ViewHolder holder = (ViewHolder) v.getTag();
// set values
if(wed.getWeight() != -1)
{
holder.text1.setText(wed.getWeight()+"");
}
else
{
holder.weight.setText("");
}
if(wed.getRepetitions() != -1)
{
holder.text2.setText(wed.getRepetitions()+"");
}
else
{
holder.reps.setText("");
}
return v;
}
这篇关于Android的 - 内的ListView EditTexts必将自定义ArrayAdapter - 跟踪变化的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！