滚动ListView时遇到问题。过了一会儿，我在logcat中得到了错误，但我知道问题是什么。
这是我的代码：
public class ListFeedAdapter extends BaseAdapter {
private ArrayList<Feed> feeds;
private LruCache<String, Bitmap> mMemoryCache;
private LayoutInflater inflater;
public ListFeedAdapter(Context context,ArrayList<Feed> feeds) {
inflater = LayoutInflater.from(context);
this.feeds = feeds;
// Bitmap Cache
final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
final int cacheSize = maxMemory / 8;
mMemoryCache = new LruCache<String, Bitmap>(cacheSize) {
@Override
protected int sizeOf(String key, Bitmap bitmap) {
return bitmap.getByteCount() / 1024;
}
};
}
public int getCount() {
return feeds.size();
}
// Permet de retourner un objet contenu dans la liste
public Object getItem(int index) {
return feeds.get(index);
}
public long getItemId(int index) {
return this.feeds.get(index).getId();
}
// * Voici la partie la plus complexe de la classe
public View getView(int position, View convertView, ViewGroup parent){
FeedView fv=null;
if (convertView == null) {
fv = new FeedView();
convertView = inflater.inflate(R.layout.feed_view, null);
fv.image=(ImageView)convertView.findViewById(R.id.imageview);
fv.description = (TextView)convertView.findViewById(R.id.description);
fv.title = (TextView)convertView.findViewById(R.id.title);
fv.pubDate = (TextView)convertView.findViewById(R.id.pub_date);
convertView.setTag(fv);
} else {
fv = (FeedView) convertView.getTag();
}
Bitmap bitmap = mMemoryCache.get(feeds.get(position).getImage());
if (bitmap != null) {
fv.image.setImageBitmap(bitmap);
} else {
ThumbnailTask getbitmap=new ThumbnailTask(fv.image, feeds.get(position).getImage(), position);
getbitmap.execute();
}
fv.description.setText(feeds.get(position).getDescription());
fv.pubDate.setText(feeds.get(position).getPubDate());
fv.title.setText(feeds.get(position).getTitle());
return convertView;
}
public static int getSizeInBytes(Bitmap bitmap) {
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
return bitmap.getByteCount();
} else {
return bitmap.getRowBytes() * bitmap.getHeight();
}
}
public class ThumbnailTask extends AsyncTask<Void,Void,Bitmap> {
private ImageView bmImage;
private String url;
private int pst;
public ThumbnailTask(ImageView image,String url,int pst) {
this.bmImage=image;
this.url=url;
this.pst=pst;
bmImage.setTag(pst);
bmImage.setImageBitmap(null);
}
@Override
protected Bitmap doInBackground(Void... arg0) {
URL url=null;
HttpURLConnection connection;
InputStream input;
Bitmap img=null;
try {
url = new URL(this.url);
connection = (HttpURLConnection) url.openConnection();
connection.connect();
input = connection.getInputStream();
img = BitmapFactory.decodeStream(input);
input.close();
} catch (IOException e) {
Log.e("img", "Error getting bitmap");
}
mMemoryCache.put(this.url, img);
return img;
}
protected void onPostExecute(Bitmap bitmap) {
super.onPostExecute(bitmap);
if(bitmap != null && ((Integer)this.bmImage.getTag()) == this.pst)
this.bmImage.setImageBitmap(bitmap);
}
}
这是LogCat数据：
09-06 21:29:17.139: E/InputEventReceiver(2216): Exception dispatching input event.
09-06 21:29:17.209: D/AndroidRuntime(2216): Shutting down VM
09-06 21:29:17.259: W/dalvikvm(2216): threadid=1: thread exiting with uncaught exception (group=0xb2a9fba8)
09-06 21:29:17.449: E/AndroidRuntime(2216): FATAL EXCEPTION: main
09-06 21:29:17.449: E/AndroidRuntime(2216): Process: com.test.fragmenttest, PID: 2216
09-06 21:29:17.449: E/AndroidRuntime(2216): java.lang.NullPointerException: key == null
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.util.LruCache.get(LruCache.java:113)
09-06 21:29:17.449: E/AndroidRuntime(2216): at com.test.fragmenttest.ListFeedAdapter.getView(ListFeedAdapter.java:113)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.widget.AbsListView.obtainView(AbsListView.java:2240)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.widget.ListView.makeAndAddView(ListView.java:1790)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.widget.ListView.fillDown(ListView.java:691)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.widget.ListView.fillGap(ListView.java:655)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.widget.AbsListView.trackMotionScroll(AbsListView.java:5136)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.widget.AbsListView.scrollIfNeeded(AbsListView.java:3236)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.widget.AbsListView.onTouchMove(AbsListView.java:3580)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.widget.AbsListView.onTouchEvent(AbsListView.java:3424)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.View.dispatchTouchEvent(View.java:7706)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2210)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1945)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2216)
09-06 21:29:17.449: E/AndroidRuntime(2216): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1959)
......