我正在實現一個應用程序的android和我遇到內存問題,同時填充從互聯網上的數據列表視圖。發生的一個奇怪的錯誤似乎是由於缺少recycling of the rows as it should normally happen而引起的,因爲它在Google I/O 2009處陳述。奇怪的行爲ListActivity和活動
當我在http://android.amberfog.com/?p=296上運行代碼時,一切都運行平穩,行視圖被回收並且listView被最佳地使用。
我現在想要在另一個活動裏面使用listView,裏面會有更多東西,因此僅僅擴展ListActivity的類是不夠的。所以,我有了下面的代碼的活動:
public class MultipleItemsList extends Activity {
private Context mContext;
private MyCustomAdapter mAdapter;
private ListView listView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mContext = this;
listView = (ListView) findViewById(R.id.listView);
mAdapter = new MyCustomAdapter(mContext);
for (int i = 1; i < 50; i++) {
mAdapter.addItem("item " + i);
}
listView.setAdapter(mAdapter);
}
}
main.xml中沒有什麼花哨的也是:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"/>
<ListView
android:id="@+id/listView"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
,以前的鏈接提出ListActivity如下:
public class MultipleItemsList extends ListActivity {
private Context mContext;
private MyCustomAdapter mAdapter;
private ListView listView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mContext = this;
mAdapter = new MyCustomAdapter(mContext);
for (int i = 1; i < 50; i++) {
mAdapter.addItem("item " + i);
}
setListAdapter(mAdapter);
}
}
適配器在以下兩種情況下都適用:
public class MyCustomAdapter extends BaseAdapter {
private static final int TYPE_ITEM = 0;
private static final int TYPE_SEPARATOR = 1;
private static final int TYPE_MAX_COUNT = TYPE_SEPARATOR + 1;
private ArrayList<String> mData = new ArrayList<String>();
private LayoutInflater mInflater;
private TreeSet<Integer> mSeparatorsSet = new TreeSet<Integer>();
public static class ViewHolder {
public TextView textView;
}
public MyCustomAdapter(Context context) {
mInflater = LayoutInflater.from(context);
}
public void addItem(final String item) {
mData.add(item);
notifyDataSetChanged();
}
public void addSeparatorItem(final String item) {
mData.add(item);
// save separator position
mSeparatorsSet.add(mData.size() - 1);
notifyDataSetChanged();
}
@Override
public int getItemViewType(int position) {
return mSeparatorsSet.contains(position) ? TYPE_SEPARATOR : TYPE_ITEM;
}
@Override
public int getViewTypeCount() {
return TYPE_MAX_COUNT;
}
@Override
public int getCount() {
return mData.size();
}
@Override
public String getItem(int position) {
return mData.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
int type = getItemViewType(position);
Log.d("myCA", "getView " + position + " " + convertView + " type = " + type);
if (convertView == null) {
holder = new ViewHolder();
switch (type) {
case TYPE_ITEM:
convertView = mInflater.inflate(R.layout.item1, null);
holder.textView = (TextView)convertView.findViewById(R.id.text);
break;
case TYPE_SEPARATOR:
convertView = mInflater.inflate(R.layout.item2, null);
holder.textView = (TextView)convertView.findViewById(R.id.textSeparator);
break;
}
convertView.setTag(holder);
} else {
holder = (ViewHolder)convertView.getTag();
}
holder.textView.setText(mData.get(position));
return convertView;
}
}
所以,我的問題是爲什麼在ListActivity的第二種情況下,視圖回收沒有問題發生,而在活動的實施中,回收會被搞砸嗎?
日誌表明,使用ListActivity時,一切都正確回收:
07-13 10:14:25.277: DEBUG/myCA(2336): getView 0 null type = 0
07-13 10:14:25.277: DEBUG/myCA(2336): getView 1 null type = 0
07-13 10:14:25.277: DEBUG/myCA(2336): getView 2 null type = 0
07-13 10:14:25.277: DEBUG/myCA(2336): getView 3 null type = 0
07-13 10:14:25.287: DEBUG/myCA(2336): getView 4 null type = 0
07-13 10:14:25.287: DEBUG/myCA(2336): getView 5 null type = 0
07-13 10:14:27.887: DEBUG/myCA(2336): getView 6 null type = 0
07-13 10:14:28.047: DEBUG/myCA(2336): getView 7 [email protected] type = 0
07-13 10:14:28.267: DEBUG/myCA(2336): getView 8 [email protected] type = 0
...
...
...
在我的執行活動,我看到以下內容:
07-13 10:11:47.517: DEBUG/myCA(2296): getView 0 null type = 0
07-13 10:11:47.517: DEBUG/myCA(2296): getView 1 [email protected] type = 0
07-13 10:11:47.517: DEBUG/myCA(2296): getView 2 [email protected] type = 0
07-13 10:11:47.517: DEBUG/myCA(2296): getView 3 and[email protected] type = 0
07-13 10:11:47.527: DEBUG/myCA(2296): getView 4 [email protected] type = 0
07-13 10:11:47.527: DEBUG/myCA(2296): getView 5 [email protected] type = 0
07-13 10:11:47.547: DEBUG/myCA(2296): getView 0 [email protected] type = 0
07-13 10:11:47.547: DEBUG/myCA(2296): getView 1 null type = 0
07-13 10:11:47.547: DEBUG/myCA(2296): getView 2 null type = 0
07-13 10:11:47.557: DEBUG/myCA(2296): getView 3 null type = 0
...
...
...
那裏顯然是有問題的回收。
我是否遺漏了一些東西,當父活動只是一個簡單的活動而不是ListActivity時,會使listView行爲正常? 有沒有人遇到過類似的東西?
感謝您的時間。
我不知道解決方案,但是您也可以將所有其他東西添加到ListActivity中,因爲ListActivity會擴展Activity。 – dbrettschneider
據我所知,listview'回收'是重新使用已經在屏幕外移動的視圖。從那以後,我看不到第二個日誌顯示有問題。您將50個項目添加到列表中,所以最壞的情況是50個視圖。你有6,對應(我猜)關於屏幕的價值。要明確檢查,每次適配器創建一個新視圖時都可以嘗試保存一個引用 - 這樣您將獲得適配器創建的視圖總數。 – 2011-07-31 20:54:11