我使用AsyncTask查询SQLite数据库 - contacts。
当我在Android模拟器上运行该代码时，它工作正常（可能是因为我在那里添加了较少的联系人），但是当我在我的手机上运行它（它有大约500个联系人）时，应用程序运行缓慢。
任何帮助将不胜感激。谢谢。
守则如下。
private class loadMoreListView extends AsyncTask<Void, Void, Void> {
ArrayList<Contact> contactsx = new ArrayList<Contact>();
@Override
protected void onPreExecute() {
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait..");
pDialog.setIndeterminate(true);
pDialog.setCancelable(false);
pDialog.show();
lv = (ListView) findViewById(R.id.blacklist);
}
@Override
protected void onPostExecute(Void unused) {
// closing progress dialog
lv.setAdapter(adapter);
pDialog.dismiss();
}
@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
ArrayList<Contact> contactItemsTemp = new ArrayList<Contact>();
adapter = new EfficientAdapter(MainActivity.this, contactItems);
DatabaseHandler db = new DatabaseHandler(MainActivity.this);
String name = "";
String id = "";
String phoneNumber = "";
// Cursor cursor = null;
List<Integer> mycontactID;
mycontactID = db.getAllIDs();
Iterator value = mycontactID.iterator();
while (value.hasNext()) {
int mg=(Integer)value.next();
ContentResolver cr = getContentResolver();
Cursor cur = cr.query(ContactsContract.Contacts.CONTENT_URI, null,
null, null, null);
// Log.d("edw",Integer.toString(mg));
if (cur.getCount() > 0) {
while (cur.moveToNext()) {
id = cur.getString(cur
.getColumnIndex(ContactsContract.Contacts._ID));
if (id.equals((mg)))
;
{
name = cur
.getString(cur
.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
if (Integer
.parseInt(cur.getString(cur
.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER))) > 0) {
Cursor pCur = cr
.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
null,
ContactsContract.CommonDataKinds.Phone.CONTACT_ID
+ " = ?",
new String[] { id }, null);
while (pCur.moveToNext()) {
Log.d("number",
pCur.getString(pCur
.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER)));
// Do something with phones
phoneNumber = pCur
.getString(pCur
.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
}
contactItemsTemp.add(new Contact(Integer
.parseInt(id), name, phoneNumber));
pCur.close();
Log.d("Name", name);
}
}
}
cur.close();
}
}
// na kanw to temp contactItems
List<Integer> messagesx;
messagesx = db.getAllIDs();
String namex = "";
String phonex = "";
for (Integer mg : messagesx) {
for (int i = 0; i < contactItemsTemp.size(); i++) {
if (contactItemsTemp.get(i).getID() == mg) {
namex = contactItemsTemp.get(i).getContactName();
phonex = contactItemsTemp.get(i).getPhoneNumber();
}
}
contactsx.add(new Contact(mg, namex, phonex));
}
adapter = new EfficientAdapter(MainActivity.this, contactsx);
db.close();
return null;
}
}
public static class EfficientAdapter extends ArrayAdapter<Contact>
implements Filterable {
private LayoutInflater mInflater;
// private Bitmap mIcon1;
private final Context context;
private final ArrayList<Contact> values;
public EfficientAdapter(Context context, ArrayList<Contact> values) {
// Cache the LayoutInflate to avoid asking for a new one each time.
super(context, R.layout.myobject, values);
mInflater = LayoutInflater.from(context);
this.context = context;
this.values = values;
}
/**
* Make a view to hold each row.
*
* @see android.widget.ListAdapter#getView1(int, android.view.View,
* android.view.ViewGroup)
*/
@Override
public View getView(final int position, View convertView,
ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.myobject, null);
holder = new ViewHolder();
holder.contact = (TextView) convertView
.findViewById(R.id.contact);
holder.ph_num = (TextView) convertView
.findViewById(R.id.ph_num);
convertView.setTag(holder);
}
else {
// Get the ViewHolder back to get fast access to the TextView
// and the ImageView.
holder = (ViewHolder) convertView.getTag();
}
convertView.setOnLongClickListener(new View.OnLongClickListener() {
private int pos = position;
@Override
public boolean onLongClick(View v) {
// TODO Auto-generated method stub
// prepare the alert box
AlertDialog.Builder alertbox = null;
alertbox = new AlertDialog.Builder(context);
// set the message to display
alertbox.setMessage("Are you sure you want to remove the contact from the blacklist?");
// add a neutral button to the alert box and assign a click
// listener
alertbox.setNeutralButton("OK",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int which) {
// TODO Auto-generated method stub
Toast.makeText(context,
"Ok button pressed " + pos,
Toast.LENGTH_SHORT).show();
DatabaseHandler db = new DatabaseHandler(
context);
db.deleteContact(values.get(position)
.getID());
db.close();
}
});
alertbox.setNegativeButton("Cancel",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int which) {
// TODO Auto-generated method stub
Toast.makeText(context,
"Cancel button pressed " + pos,
Toast.LENGTH_SHORT).show();
}
});
alertbox.show();
return true;
}
});
convertView.setOnClickListener(new OnClickListener() {
private int pos = position;
@Override
public void onClick(View v) {
// Toast.makeText(context, "Click-" + pos,
// Toast.LENGTH_SHORT)
// .show();
}
});
holder.contact.setText(getItem(position).getContactName());
holder.ph_num.setText(getItem(position).getPhoneNumber());
return convertView;
}
static class ViewHolder {
TextView contact;
TextView ph_num;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return values.size();
}
@Override
public Contact getItem(int position) {
// TODO Auto-generated method stub
return values.get(position);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
@Override
public Filter getFilter() {
// TODO Auto-generated method stub
return null;
}
public void add(Contact con) {
values.add(con);
notifyDataSetChanged();
}
public void replace(int index, Contact con) {
values.set(index, con);
notifyDataSetChanged();
}
public void clear() {
values.clear();
notifyDataSetChanged();
}
public void remove(Contact con) {
values.remove(con);
notifyDataSetChanged();
}
}
答案 0 :(得分：0)
好吧，我不确定异常，但似乎您在初始化之前尝试向contactx arraylist添加联系人。您将其声明为实例变量，但在doInBackground（）方法结束之前不要初始化它。这将抛出空指针...
尝试放线......
contactx = new ArrayList<Contact>();
在你的onPreExecute（）方法中。
答案 1 :(得分：0)
lv = (ListView) findViewById(R.id.blacklist);
我会看看这一行。您正试图从嵌套类中查找列表视图。虽然这将在UI线程上运行，但AsyncTask仍然不是一个活动。我相信你的null点是因为你的listview引用是null，因为AsyncTask的一个实例无法检索视图。
答案 2 :(得分：0)
为什么适配器创建两次（仅使用一次），并且在runInBackground中？是否应该在获取原始数据后创建它，在onPostExecute中？
您可能没有很好地实现适配器吗？你看过google的“listView世界”视频吗？请显示适配器的代码。
崩溃的例外是什么？