在Android开发页面中，我们对ListViews的Custom ArrayAdapter有以下引用：
＆＃34;绝对不能保证调用getView（）的顺序也不能保证多少次。＆＃34;
当我有以下内容并且多次调用getView时，它没有问题，因为我只是回收了视图而不是再次对它们进行充气：
@Override
public void getView(int position, View convertView, ViewGroup parent){
Log.i(TAG, "getView of position " + String.valueOf(position) + " is called");
View view = convertView;
if(view == null){
view = inflater.inflate(layoutResourceId, parent, false);
TextView myTextView1 = (TextView) view.findViewById(R.id.my_tv1);
Button myButton1 = (Button) view.findViewById(R.id.my_btn1);
... // More views
view.setTag(new MyViewHolder(myTextView1, myButton1, ...));
}
MyViewHolder h = (MyViewHolder) view.getTag();
h.myTextView1.setText("Some text");
h.myButton1.setText("Some button text");
h.myButton1.setEnabled(buttonEnabled);
}
使用if(view == null) -> inflate view and create ViewHolder; else -> use ViewHolder of Tag的问题是当您在列表中快速向上和向下滚动时，列表中项目的顺序会发生变化。可能是因为引用的第一部分：
＆＃34;绝对不能保证调用getView（）的顺序......＆＃34;
虽然我认为它只是ListViews本身而不是适配器的错误。 （不确定，但无论原因是什么，都是一个BUG。）
到目前为止，我能够解决这个问题的唯一方法就是让视图膨胀：
@Override
public void getView(int position, View convertView, ViewGroup parent){
Log.i(TAG, "getView of position " + String.valueOf(position) + " is called");
// NOTE: In Android it's recommended to use the convertView as the view, instead of
// retrieving it every time from the inflater. But since there is a bug in Android ListViews
// which changes the order of the Items when you scroll up- and down real fast,
// I use the inflater every time and ignore the convertView parameter
view = inflater.inflate(layoutResourceId, parent, false);
TextView myTextView1 = (TextView) view.findViewById(R.id.my_tv1);
Button myButton1 = (Button) view.findViewById(R.id.my_btn1);
... // More views
view.setTag(new MyViewHolder(myTextView1, myButton1, ...));
MyViewHolder h = (MyViewHolder) view.getTag();
h.myTextView1.setText("Some text");
h.myButton1.setText("Some button text");
h.myButton1.setEnabled(buttonEnabled);
}
一切正常，当快速上下滚动时，项目的顺序仍然存在。但现在性能正在迅速下降..很长一段时间我都忽略了这个性能问题，但是现在我在对项目布局进行了一些更改后面临一个新问题。从来没有遇到过这个问题，但是现在我（因为一些未知的原因）面对报价的第二部分：
＆＃34;绝对不能保证会调用多少次getView（）...＆＃34;
现在，ListView包含14个可见元素。当我使用此适配器转到包含ListView的ChecklistActivity时，我收到以下Logcat消息：
07-23 03:17:14.516: V/MyAdapter(1395): getView(0)
07-23 03:17:16.556: V/MyAdapter(1395): getView(1)
07-23 03:17:16.946: V/MyAdapter(1395): getView(2)
07-23 03:17:17.316: V/MyAdapter(1395): getView(3)
07-23 03:17:17.776: V/MyAdapter(1395): getView(4)
07-23 03:17:18.136: V/MyAdapter(1395): getView(5)
07-23 03:17:18.286: V/MyAdapter(1395): getView(6)
07-23 03:17:18.466: V/MyAdapter(1395): getView(7)
07-23 03:17:18.576: V/MyAdapter(1395): getView(8)
07-23 03:17:18.806: V/MyAdapter(1395): getView(9)
07-23 03:17:19.016: V/MyAdapter(1395): getView(10)
07-23 03:17:19.246: V/MyAdapter(1395): getView(11)
07-23 03:17:19.346: D/dalvikvm(1395): GC_FOR_ALLOC freed 220K, 10% free 5545K/6108K, paused 82ms, total 85ms
07-23 03:17:19.526: V/MyAdapter(1395): getView(12)
07-23 03:17:19.666: V/MyAdapter(1395): getView(13)
07-23 03:17:19.786: V/MyAdapter(1395): getView(14)
07-23 03:17:20.046: I/Choreographer(1395): Skipped 1491 frames! The application may be doing too much work on its main thread.
07-23 03:17:20.066: V/ChecklistActivity(1395): onCreateOptionsMenu
07-23 03:17:20.406: I/Choreographer(1395): Skipped 64 frames! The application may be doing too much work on its main thread.
07-23 03:17:20.416: V/MyAdapter(1395): getView(2)
07-23 03:17:20.576: V/MyAdapter(1395): getView(3)
07-23 03:17:20.866: V/MyAdapter(1395): getView(4)
07-23 03:17:21.036: V/MyAdapter(1395): getView(5)
07-23 03:17:21.206: V/MyAdapter(1395): getView(6)
07-23 03:17:21.396: V/MyAdapter(1395): getView(7)
07-23 03:17:21.606: V/MyAdapter(1395): getView(8)
07-23 03:17:21.866: V/MyAdapter(1395): getView(9)
07-23 03:17:22.116: V/MyAdapter(1395): getView(10)
07-23 03:17:22.336: V/MyAdapter(1395): getView(11)
07-23 03:17:22.496: V/MyAdapter(1395): getView(12)
07-23 03:17:22.646: V/MyAdapter(1395): getView(13)
07-23 03:17:22.806: V/MyAdapter(1395): getView(14)
07-23 03:17:23.616: V/MainActivity(1395): onStop
07-23 03:17:23.616: I/Choreographer(1395): Skipped 160 frames! The application may be doing too much work on its main thread.
07-23 03:17:24.246: I/Choreographer(1395): Skipped 112 frames! The application may be doing too much work on its main thread.
07-23 03:17:24.286: V/MyAdapter(1395): getView(4)
07-23 03:17:24.396: D/dalvikvm(1395): GC_FOR_ALLOC freed 397K, 8% free 6099K/6568K, paused 100ms, total 107ms
07-23 03:17:24.646: V/MyAdapter(1395): getView(5)
07-23 03:17:24.756: V/MyAdapter(1395): getView(6)
07-23 03:17:24.886: V/MyAdapter(1395): getView(7)
07-23 03:17:25.046: V/MyAdapter(1395): getView(8)
07-23 03:17:25.196: V/MyAdapter(1395): getView(9)
07-23 03:17:25.356: V/MyAdapter(1395): getView(10)
07-23 03:17:25.486: V/MyAdapter(1395): getView(11)
07-23 03:17:25.596: V/MyAdapter(1395): getView(12)
07-23 03:17:25.726: V/MyAdapter(1395): getView(13)
07-23 03:17:25.846: V/MyAdapter(1395): getView(14)
07-23 03:17:26.146: I/Choreographer(1395): Skipped 35 frames! The application may be doing too much work on its main thread.
07-23 03:17:26.406: V/MyAdapter(1395): getView(6)
07-23 03:17:26.586: V/MyAdapter(1395): getView(7)
07-23 03:17:26.786: V/MyAdapter(1395): getView(8)
07-23 03:17:26.896: V/MyAdapter(1395): getView(9)
07-23 03:17:27.156: V/MyAdapter(1395): getView(10)
07-23 03:17:27.296: V/MyAdapter(1395): getView(11)
07-23 03:17:27.436: V/MyAdapter(1395): getView(12)
07-23 03:17:27.646: V/MyAdapter(1395): getView(13)
07-23 03:17:27.766: V/MyAdapter(1395): getView(14)
07-23 03:17:28.186: I/Choreographer(1395): Skipped 56 frames! The application may be doing too much work on its main thread.
07-23 03:17:28.426: D/dalvikvm(1395): GC_FOR_ALLOC freed 523K, 9% free 6713K/7308K, paused 108ms, total 112ms
07-23 03:17:28.506: I/Choreographer(1395): Skipped 60 frames! The application may be doing too much work on its main thread.
07-23 03:17:28.606: V/MyAdapter(1395): getView(8)
07-23 03:17:28.806: V/MyAdapter(1395): getView(9)
07-23 03:17:28.926: V/MyAdapter(1395): getView(10)
07-23 03:17:29.136: V/MyAdapter(1395): getView(11)
07-23 03:17:29.256: V/MyAdapter(1395): getView(12)
07-23 03:17:29.406: V/MyAdapter(1395): getView(13)
07-23 03:17:29.516: V/MyAdapter(1395): getView(14)
07-23 03:17:29.816: I/Choreographer(1395): Skipped 35 frames! The application may be doing too much work on its main thread.
07-23 03:17:30.096: V/MyAdapter(1395): getView(9)
07-23 03:17:30.216: V/MyAdapter(1395): getView(10)
07-23 03:17:30.366: V/MyAdapter(1395): getView(11)
07-23 03:17:30.496: V/MyAdapter(1395): getView(12)
07-23 03:17:30.646: V/MyAdapter(1395): getView(13)
07-23 03:17:30.796: V/MyAdapter(1395): getView(14)
07-23 03:17:31.166: I/Choreographer(1395): Skipped 53 frames! The application may be doing too much work on its main thread.
07-23 03:17:31.376: I/Choreographer(1395): Skipped 32 frames! The application may be doing too much work on its main thread.
07-23 03:17:31.426: V/MyAdapter(1395): getView(10)
07-23 03:17:31.546: V/MyAdapter(1395): getView(11)
07-23 03:17:31.736: V/MyAdapter(1395): getView(12)
07-23 03:17:31.906: V/MyAdapter(1395): getView(13)
07-23 03:17:32.046: V/MyAdapter(1395): getView(14)
07-23 03:17:32.306: I/Choreographer(1395): Skipped 31 frames! The application may be doing too much work on its main thread.
07-23 03:17:32.536: I/Choreographer(1395): Skipped 35 frames! The application may be doing too much work on its main thread.
07-23 03:17:32.606: V/MyAdapter(1395): getView(11)
07-23 03:17:32.816: V/MyAdapter(1395): getView(12)
07-23 03:17:32.986: D/dalvikvm(1395): GC_FOR_ALLOC freed 729K, 10% free 7323K/8124K, paused 121ms, total 128ms
07-23 03:17:33.166: V/MyAdapter(1395): getView(13)
07-23 03:17:33.496: V/MyAdapter(1395): getView(14)
07-23 03:17:34.056: V/MyAdapter(1395): getView(12)
07-23 03:17:34.186: V/MyAdapter(1395): getView(13)
07-23 03:17:34.316: V/MyAdapter(1395): getView(14)
07-23 03:17:34.596: I/Choreographer(1395): Skipped 34 frames! The application may be doing too much work on its main thread.
07-23 03:17:34.846: I/Choreographer(1395): Skipped 36 frames! The application may be doing too much work on its main thread.
07-23 03:17:34.906: V/MyAdapter(1395): getView(13)
07-23 03:17:35.016: V/MyAdapter(1395): getView(14)
07-23 03:17:35.546: V/MyAdapter(1395): getView(14)
07-23 03:17:36.066: I/Choreographer(1395): Skipped 31 frames! The application may be doing too much work on its main thread.
我完全不知道为什么这么多次被召唤，但我希望每次只召唤一次。如果有人知道这个快速滚动错误的解决方案，它会改变订单而不会在getView（）中每次都膨胀View，这也将是一个巨大的帮助。
PS：忽略我目前正在处理的第一个07-23 03:17:20.046: I/Choreographer(1395): Skipped 1491 frames! The application may be doing too much work on its main thread. ..充气视图是性能缺乏的原因之一，但我还有一些其他问题试图解决。
但是，为什么Android不能拥有强大的ArrayAdapter。当有人快速上下滚动时，不会改变项目顺序的那个。或者一个选项，这样你就可以选择记住可见区域之外的项目..如果你记得很多项目，这理论上也会产生性能问题，但它会解决很多问题，包括那些再次重置EditText输入的问题在它们离开可见区域之后。那么我们就不应该使用TextWatchers，带有持有人的标签等......
好的，我现在正在旁观......它的方式就是这样，我无法改变它。因此，让我们只关注修复上面解释的问题（快速滚动错误，不会每次都膨胀而且getView在创建时不会被调用多次）。
编辑1：
有关我代码其他部分的更多信息：
checklist_activity.xml：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ListView
android:id="@android:id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:descendantFocusability="afterDescendants" />
</RelativeLayout>
list_item.xml外部布局：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/item_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<!-- height is wrap content since I have views that are Visible / Gone based on the Item's state -->
<!-- All my View elements -->
</RelativeLayout>
对于我的项目，请参阅this different stackoverflow question of mine。
编辑2：
下面是我当前的MyAdapter.java类的副本（PS：删除了注释，导入和日志以便于阅读）。当我在模拟器中快速向上和向下滚动时，图像保持不变，但文本（产品名称，价格等）正在混淆。我有一个按类别和产品名称排序的列表，我想列出在ListView中保留此订单。
public class MyAdapter extends ArrayAdapter<OrderedProductItem>
{
private static final String TAG = "MyAdapter";
public static MyAdapter mAdapter;
private Context context;
private int layoutResourceId;
private LayoutInflater inflater;
public MyAdapter(Context c, int layoutId, ArrayList<OrderedProductItem> objects){
super(c, layoutId, objects);
layoutResourceId = layoutId;
context = c;
inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
mAdapter = this;
}
private OnTouchListener itemOnTouchListener = new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
if(v instanceof EditText){
EditText et = (EditText)v;
et.setFocusable(true);
et.setFocusableInTouchMode(true);
}
else{
ListItemTagHolder h = (ListItemTagHolder) v.getTag();
h.etAmount.setFocusable(false);
h.etAmount.setFocusableInTouchMode(false);
h.actvName.setFocusable(false);
h.actvName.setFocusableInTouchMode(false);
}
return false;
}
};
@Override
public View getView(int position, View convertView, ViewGroup parent){
View view = convertView;
ListItemTagHolder h;
if(view == null){
view = inflater.inflate(layoutResourceId, parent, false);
RelativeLayout rl = (RelativeLayout) view.findViewById(R.id.item_layout);
h = new ListItemTagHolder(rl);
view.setTag(h);
}
else
h = (ListItemTagHolder) view.getTag();
/*
View view = inflater.inflate(layoutResourceId, parent, false);
RelativeLayout rl = (RelativeLayout) view.findViewById(R.id.item_layout);
view.setTag(new ListItemTagHolder(rl));
final ListItemTagHolder h = (ListItemTagHolder) view.getTag();
*/
if(h != null){
h.orderedProductItem = Controller.getInstance().getOrderedProductItems().get(position);
MainActivity.getImageLoader().imageForImageView(h.orderedProductItem.getCheckState().rID(), h.imageView);
String productName = Controller.getInstance().getProductById(h.orderedProductItem.getProductId()).getName();
// (I use a Validation-class to compare Strings or Check if they aren't null/empty)
if(!V.compare(h.tvName.getText().toString(), productName, true, true))
h.tvName.setText(productName);
String priceString = C.doubleToPrice(Controller.getInstance().getProductById(h.orderedProductItem.getProductId()).getPrice(), "€", true);
if(!V.compare(h.tvPrice.getText().toString(), priceString, true, true))
h.tvPrice.setText(priceString);
String resultAmount = String.valueOf(h.orderedProductItem.getResultAmount());
if(!V.compare(h.etAmount.getText().toString(), resultAmount, true, true))
h.etAmount.setText(resultAmount);
ChecklistActivity.cActivity.updateAutoCompleteTextViewWithFilter(h, h.orderedProductItem.getSelectedFilter());
ChecklistActivity.cActivity.updateTagsSpinner(h, null);
h.etAmount.addTextChangedListener(new MyTextWatcher(h.etAmount));
h.actvName.addTextChangedListener(new MyTextWatcher(h.actvName));
h.etAmount.setTag(h.orderedProductItem);
h.actvName.setTag(h.orderedProductItem);
ChecklistActivity.cActivity.updateChangeEditTexts(view, h);
view.setOnTouchListener(itemOnTouchListener);
h.etAmount.setOnTouchListener(itemOnTouchListener);
h.actvName.setOnTouchListener(itemOnTouchListener);
}
return view;
}
}
使用以下Holder级别：
public class ListItemTagHolder
{
public final RelativeLayout relativeLayout;
public final LinearLayout leftLL, rightLL;
public final ImageView imageView;
public final TextView tvName, tvPrice, tvTags;
public final EditText etAmount;
public final AutoCompleteTextView actvName;
public final Spinner spTags;
public final ImageButton btnTags;
public final Space spaceImage, spacePrice;
public OrderedProductItem orderedProductItem;
public ListItemTagHolder(RelativeLayout layout){
relativeLayout = layout;
leftLL = (LinearLayout) relativeLayout.findViewById(R.id.left_ll);
rightLL = (LinearLayout) relativeLayout.findViewById(R.id.right_ll);
imageView = (ImageView) relativeLayout.findViewById(R.id.image);
tvName = (TextView) relativeLayout.findViewById(R.id.tv_product_name);
tvPrice = (TextView) relativeLayout.findViewById(R.id.tv_price);
tvTags = (TextView) relativeLayout.findViewById(R.id.tv_tags);
etAmount = (EditText) relativeLayout.findViewById(R.id.et_result_amount);
actvName = (AutoCompleteTextView) relativeLayout.findViewById(R.id.actv_result_name);
spTags = (Spinner) relativeLayout.findViewById(R.id.sp_tags);
btnTags = (ImageButton) relativeLayout.findViewById(R.id.btn_tags);
spaceImage = (Space) relativeLayout.findViewById(R.id.filler_space_image);
spacePrice = (Space) relativeLayout.findViewById(R.id.filler_space_price);
}
}
PSS：这三个更新方法重新应用Spinner / EditTexts / AutoCompleteTextView中OrderedProductItem字段的新数据。我已将它们放在ChecklistActivity中，因为我也在那里使用相同的方法。这对我面临的问题也没有任何影响，无论是直接将它们放在getView方法中，还是像我在这里一样调用它们。
答案 0 :(得分：3)
我建议您稍微更改一下代码。我的ListView的getView（）总是看起来像这样，我没有遇到任何问题。
@Override
public void getView(int position, View convertView, ViewGroup parent) {
View view = convertView;
MyViewHolder holder = new MyViewHolder();
if (view == null) {
view = inflater.inflate(layoutResourceId, null);
holder.textView1 = (TextView) view.findViewById(R.id.my_tv1);
holder.button1 = (Button) view.findViewById(R.id.my_btn1);
// More views
view.setTag(holder);
} else {
holder = (MyViewHolder) view.getTag();
}
holder.textView1.setText("Some text");
holder.button1.setText("Some button text");
holder.button1.setEnabled(buttonEnabled);
}
public static class MyViewHolder {
public TextView textView1;
public Button button1;
// ... and so on
}
答案 1 :(得分：1)
这不是错误！
getView（）调用了多少次并不重要。每次android想要在Listview中显示一行时都会调用此方法。
您可以覆盖Adapter的getItem（int position），以便在每个位置返回您想要的每个Object。除此之外，请检查list_item高度。
@Override
public Object getItem(int position) {
Object item = null;
if (position >= 0 && position < mData.size()) {
item = mData.get(position);
}
else {
Log.e(TAG, "Bad position in getItem");
}
return item;
}
mData是绑定到listview的数据的ArrayList。
请注意，在getView（）中，您应该为所有视图设置值。这很重要。
答案 2 :(得分：0)
为什么要在ListItemTagHolder类中保存OrderedProductItem对象？ 你总是用这个命令获取数据
getItem(position)
并且您不需要在ListItemTagHolder类中保存此对象。也许这个命令
h.orderedProductItem = Controller.getInstance().getOrderedProductItems().get(position);
返回错误数据!! 我想如果你更改上面的命令并从ListItemTagHolder类中移出，你的问题将得到解决。 ：）