我正在开发一款Android应用，但我是新手而且我被卡住了...... 我的ListView单个元素有一个ImageView和一些TextViews，但有时（当我滚动页面并且有超过7-8个元素时）它不会在右侧显示正确的图像。 我使用自定义图像加载器来管理下载的图像。 这是我的适配器：
public class AddVideogameActivityAdapter extends BaseAdapter {
private ArrayList<Videogame> videogames;
private Typeface typefaceMedium;
private Typeface typefaceLight;
private ImageLoader loader;
private LayoutInflater mInflater;
public AddVideogameActivityAdapter(Context context, ArrayList<Videogame> results) {
videogames = results;
mInflater = LayoutInflater.from(context);
typefaceMedium = Typeface.createFromAsset(context.getAssets(), "Roboto-Medium.ttf");
typefaceLight = Typeface.createFromAsset(context.getAssets(), "Roboto-Light.ttf");
loader = new ImageLoader(context);
}
public int getCount() {
return videogames.size();
}
public Object getItem(int position) {
return videogames.get(position);
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.list_element,null);
holder = new ViewHolder();
holder.imgView = (ImageView) convertView.findViewById(R.id.thumbView);
holder.txtName = (TextView) convertView.findViewById(R.id.elementView);
holder.txtPlatform = (TextView) convertView.findViewById(R.id.elementView2);
convertView.setTag(holder);
}
else {
holder = (ViewHolder) convertView.getTag();
}
try {
Videogame vgame = (Videogame) videogames.get(position);
holder.txtName.setText(vgame.getTitle());
holder.txtName.setTypeface(typefaceMedium);
holder.txtPlatform.setText(videogames.get(position).getPlatform());
holder.txtPlatform.setTypeface(typefaceLight);
holder.imgUrl = videogames.get(position).getImage();
loader.display(holder.imgUrl, holder.imgView, R.drawable.youtube_icon);
}
catch (Exception e) {
e.printStackTrace();
Log.e(com.example.ludos2_0.MainActivity.TAG,
"Exception: " + e.getLocalizedMessage());
}
return convertView;
}
static class ViewHolder {
TextView txtName;
TextView txtPlatform;
public String imgUrl;
ImageView imgView;
}
}
对不起我的英文，谢谢你的帮助！ 修改 这里也是装载机：
public class ImageLoader implements ComponentCallbacks2 {
private TCLruCache cache;
public ImageLoader(Context context) {
ActivityManager am = (ActivityManager) context.getSystemService(
Context.ACTIVITY_SERVICE);
int memoryClass = am.getMemoryClass() * 1024 * 1024;
cache = new TCLruCache(memoryClass);
}
public void display(String url, ImageView imageview, int defaultresource) {
imageview.setImageResource(defaultresource);
Bitmap image = cache.get(url);
if (image != null) {
imageview.setImageBitmap(image);
}
else {
new SetImageTask(imageview).execute(url);
}
}
private class TCLruCache extends LruCache<String, Bitmap> {
public TCLruCache(int maxSize) {
super(maxSize);
}
}
private class SetImageTask extends AsyncTask<String, Void, Integer> {
private ImageView imageview;
private Bitmap bmp;
public SetImageTask(ImageView imageview) {
this.imageview = imageview;
}
@Override
protected Integer doInBackground(String... params) {
String url = params[0];
try {
bmp = getBitmapFromURL(url);
if (bmp != null) {
cache.put(url, bmp);
}
else {
return 0;
}
} catch (Exception e) {
e.printStackTrace();
return 0;
}
return 1;
}
@Override
protected void onPostExecute(Integer result) {
if (result == 1) {
imageview.setImageBitmap(bmp);
}
super.onPostExecute(result);
}
private Bitmap getBitmapFromURL(String src) {
try {
URL url = new URL(src);
HttpURLConnection connection
= (HttpURLConnection) url.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
Bitmap myBitmap = BitmapFactory.decodeStream(input);
return myBitmap;
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
}
}
RE-修改 活动代码：
public class AddVideogameActivity extends ListActivity {
private TextView searchField = null;
private final Handler handler = new Handler();
private ArrayList<Videogame> videogamesList = null;
private static AddVideogameActivity mContext = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_book);
mContext = this;
searchField = (TextView) findViewById(R.id.searchField);
searchField.setMaxLines(1);
searchField.setOnFocusChangeListener(new OnFocusChangeListener() {
@Override
public void onFocusChange(View v, boolean hasFocus) {
searchField.setHint("");
}
});
// Setup the list view and its listener
getListView().setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Log.d(MainActivity.TAG,
"AddBookActivity ---> AddButton:onClick()");
// Sets typefaces for TextView
String videogameId = videogamesList.get(position).getId();
String videogameName = videogamesList.get(position).getTitle();
String thumbnail = videogamesList.get(position).getThumbnail();
String description = videogamesList.get(position)
.getDescription();
String image = videogamesList.get(position).getImage();
String platform = videogamesList.get(position).getPlatform();
if (videogameName != null && videogameName.length() > 0
&& thumbnail != null && thumbnail.length() > 0
&& description != null && description.length() > 0
&& image != null && image.length() > 0
&& platform != null && platform.length() > 0) {
if (ListsManager.getInstance().addVideogame(
new Videogame(videogameId, videogameName,
thumbnail, image, description, platform)) == 0) {
Log.d(MainActivity.TAG,
"AddBookActivity --> Videogame:[" + videogameId
+ "@" + videogameName + "]");
Toast toast = Toast.makeText(mContext, "["
+ videogameName + "] Saved !",
Toast.LENGTH_LONG);
toast.show();
} else {
Log.e(MainActivity.TAG,
"AddBookActivity --> Error ! Videogame already in the list ! ");
Toast toast = Toast.makeText(mContext,
"Error! Videogame already in the list!",
Toast.LENGTH_LONG);
toast.show();
}
} else {
Log.e(MainActivity.TAG,
"AddBookActivity --> Error ! Invalid Videogame Name or Thumbnail or Id or Deck");
Toast toast = Toast
.makeText(
mContext,
"Error ! Invalid Videogame Name or Thumbnail or Id or Deck",
Toast.LENGTH_LONG);
toast.show();
}
Intent newIntent = new Intent(getApplicationContext(),
MainActivity.class);
startActivity(newIntent);
}
});
// Setup the search button and its listener
Button searchButton = (Button) findViewById(R.id.searchButton);
searchButton.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Log.d(com.example.ludos2_0.MainActivity.TAG, "Search Game ...");
String searchInputString = searchField.getText().toString();
if (searchInputString != null && searchInputString.length() > 0) {
try {
String requestURL = ("http://www.giantbomb.com/api/search/?api_key=fcf60d6d67b98b0d17b3905d1a90b3fd31ed1e8e&format=json&query="
+ Uri.encode(searchInputString) + "&resources=game");
// String requestURL =
// String.format("https://gdata.youtube.com/feeds/api/videos?v=2&alt=jsonc&category=Music&orderby=relevance&q=%s",Uri.encode(searchInputString));
Log.d(com.example.ludos2_0.MainActivity.TAG, requestURL);
DownloadGiantBombJSONData giantbombAsyncTask = new DownloadGiantBombJSONData();
giantbombAsyncTask.execute(new String[] { requestURL });
} catch (Exception e) {
e.printStackTrace();
}
}
}
});
if (videogamesList == null)
videogamesList = new ArrayList<Videogame>();
else
updateVideogamesListView(videogamesList);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.add_book, menu);
return true;
}
@Override
protected void onResume() {
super.onResume();
}
@Override
protected void onPause() {
super.onPause();
}
public void updateVideogamesListView(ArrayList<Videogame> values) {
AddVideogameActivityAdapter adapter = new AddVideogameActivityAdapter(this, values);
setListAdapter(adapter);
}
@Override
protected void onDestroy() {
super.onDestroy();
}
}
构建ListView所涉及的其他类是REST类和下载并解析JSon文件的AsyncTask类。
答案 0 :(得分：0)
ListView看起来像什么，看起来像这样：
<ListView android:id="@id/android:list"
android:layout_weight="1"
android:layout_width="match_parent"
android:layout_height="0dip" ></ListView>
特别是id的{{1}}。检查你的布局文件，可能是那里存在的bug。