我正在使用AsyncTask作为内部类,其签名如下:
public abstract class BaseFragmentActivity extends FragmentActivity {
static final int PROGRESS_DIALOG = 0;
Dialog progessDialog;
public abstract void displayData(T output);
@Override
protected Dialog onCreateDialog(int id) {
if (id == PROGRESS_DIALOG) {
ProgressDialog progressDialog = ProgressDialog.show(this, "",
"Loading. Please wait...", true);
progessDialog = progressDialog;
}
return progessDialog;
}
class PerformOPTask<T> extends AsyncTask<Void, String, T> {
// connector=new JSONConnector();
Connector connector;
String curUrl;
Class<T> clazz;
PerformOPTask(String url, Class<T> curClazz) {
//connector = new UnitTestConnector();
connector = new JSONConnector();
curUrl = url;
clazz = curClazz;
}
@Override
protected T doInBackground(Void... params) {
return connector.getData(URLUtils.getFormattedUrl(curUrl),clazz);
}
@Override
protected void onPostExecute(T output) {
displayData(output);
}
}
公共抽象类BaseListFragmentActivity继承自BaseFragmentActivity,实现OnItemClickListener和OnClickListener接口。
protected ListView mList;
/** Called when the activity is first created. */
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.table_list);
CommonUtil.getActionBarWithBackButton(this,getLayoutInflater());
mList=(ListView)findViewById(R.id.table_list_listView);
mList.setOnItemClickListener(this);
}
public void onBackABButtonPressed(View view) {
finish();
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
@Override
public abstract void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3);
公共类ListAccountsActivity扩展自BaseListFragmentActivity {
protected Acct[] mItems;
private String[] mIcons;
protected boolean displayHandledBySubClass=false;
/** Called when the activity is first created. */
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
// Create an array of Strings, that will be put to our ListActivity
// Log.i("MY INFO",this.runJSONParser().getAcct().toString());
AccountData actData = new AccountData();
//actData=(AccountData)
new PerformOPTask<AccountData>(getString(R.string.get_account),AccountData.class).execute();
showDialog(PROGRESS_DIALOG);
//.getData(URLUtils.getFormattedUrl(getString(R.string.get_account)),actData);
}
@Override
public void onItemClick(AdapterView<?> lv, View view, int position, long id) {
// super.onListItemClick(l, v, position, id);
// Get the item that was clicked
Acct account = (Acct) mList.getAdapter().getItem(position);
Intent intent=new Intent(this,AccountDetailViewActivity.class);
intent.putExtra("selectedAccount",account);
startActivity(intent);
}
@Override
**public void displayData(ServerOutput output){** //error here
if(displayHandledBySubClass){
//handle display in subclass
handleDisplayData(output);
}
else {
Acct[] accountArray = new Acct[((AccountData)output).getAccount().size()];
mItems = ((AccountData)output).getAccount().toArray(accountArray);
IWMArrayAdapter<Acct> adapter = new IWMArrayAdapter<Acct>(this, mItems);
adapter.setIcons(mIcons);
adapter.setArrowNeeded();
//mList is superClassVariable
mList.setAdapter(adapter);
dismissDialog(PROGRESS_DIALOG);
adapter.notifyDataSetChanged();
}
}
public void handleDisplayData(SrOutput output){
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
//Toast.makeText(this, "Tapped search", Toast.LENGTH_SHORT).show();
super.onCreateOptionsMenu(menu);
MenuInflater menuInflater = getMenuInflater();
menuInflater.inflate(R.menu.list_servers_menu, menu);
// Calling super after populating the menu is necessary here to ensure
// that the
// action bar helpers have a chance to handle this event.
return true;
}
}
我的外部类中的回调方法displayData具有以下方法签名。
public abstract <T> void displayData(T output);
现在,我想扩展我的外部类,并根据我所期望的响应对象类型,在扩展类中以不同方式实现displaydata方法。当我在子类中定义以下方法时,我会得到一个错误,即无效的覆盖:
@Override
public void displayData(ServerOutput output){}
Asynctask被调用为:
new PerformOPTask<AccountData>(getString(R.string.get_account),AccountData.class).execute();
这该怎么正确地做呢?由于我对泛型的东西比较陌生,所以有些困惑。非常感谢您提前给予的任何帮助。