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我想在我的Android應用程序的尾部按鈕的末尾做一個列表視圖。 我想從我的數據庫中讀取元素，將它們放入使用限制sql命令的列表中，每次按下頁腳按鈕時都會結束，然後我想從數據庫中加載下一個元素等。使用我的數據庫的異步調用
代碼有效罰款，直到我按下我的異步調用按鈕，然後我得到一個異常。
這是我的課：
public class UIHistoryListActivity extends ListActivity {
ProgressDialog pDialog;
EfficientAdapter adap;
Databasehandler db = new Databasehandler(this);
List<Message> messages;
ArrayList<Message> menuItems = new ArrayList<Message>();
int current_page = 0;
int index = 0;
int limit = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_main);
android.text.format.DateFormat.format("yyyy-MM-dd hh:mm:ss",
new java.util.Date());
db.addMessage(new Message("6983583727", "Hi Lakis", 1,
(String) android.text.format.DateFormat.format(
"yyyy-MM-dd hh:mm:ss", new java.util.Date())));
db.addMessage(new Message("1234567789", "Hi Takis", 1,
(String) android.text.format.DateFormat.format(
"yyyy-MM-dd hh:mm:ss", new java.util.Date())));
db.addMessage(new Message("1234344789", "Hi Makis", 1,
(String) android.text.format.DateFormat.format(
"yyyy-MM-dd hh:mm:ss", new java.util.Date())));
db.addMessage(new Message("1234553229", "Hi Sakis", 0,
(String) android.text.format.DateFormat.format(
"yyyy-MM-dd hh:mm:ss", new java.util.Date())));
db.addMessage(new Message("1234567781", "Hi Akis", 1,
(String) android.text.format.DateFormat.format(
"yyyy-MM-dd hh:mm:ss", new java.util.Date())));
db.addMessage(new Message("6983583727", "Hi Qakis", 1,
(String) android.text.format.DateFormat.format(
"yyyy-MM-dd hh:mm:ss", new java.util.Date())));
db.addMessage(new Message("1234567789", "Hi Wakis", 1,
(String) android.text.format.DateFormat.format(
"yyyy-MM-dd hh:mm:ss", new java.util.Date())));
db.addMessage(new Message("1234344789", "Hi Eakis", 1,
(String) android.text.format.DateFormat.format(
"yyyy-MM-dd hh:mm:ss", new java.util.Date())));
db.addMessage(new Message("1234553229", "Hi Yakis", 0,
(String) android.text.format.DateFormat.format(
"yyyy-MM-dd hh:mm:ss", new java.util.Date())));
db.addMessage(new Message("1234567781", "Hi Ukis", 1,
(String) android.text.format.DateFormat.format(
"yyyy-MM-dd hh:mm:ss", new java.util.Date())));
//putting the first 5 messages of my db on the list
messages = db.getMessages(0, 5);
index += 5;
limit = limit + 5;
for (Message mg : messages) {
menuItems.add(new Message(mg.getID(), mg.getPhoneNumber(), mg
.getBody(), mg.getStatus(), mg.getDate()));
}
/*
* menuItems.add(new Message(1, "1234553229", "Hi Sakis", 0, "lala"));
* menuItems.add(new Message(1, "1234553229", "Hi Lakis", 0, "lala"));
* menuItems.add(new Message(1, "1234553229", "Hi Takis", 0, "lala"));
* menuItems.add(new Message(1, "1234553229", "Hi Aakis", 0, "lala"));
* menuItems.add(new Message(1, "1234553229", "Hi Qakis", 1, "lala"));
* menuItems.add(new Message(1, "1234553229", "Hi Wakis", 1, "lala"));
* menuItems.add(new Message(1, "1234553229", "Hi Eakis", 0, "lala"));
* menuItems.add(new Message(1, "1234553229", "Hi Rakis", 0, "lala"));
* menuItems.add(new Message(1, "1234553229", "Hi Yakis", 1, "lala"));
* menuItems.add(new Message(1, "1234553229", "Hi Uakis", 0, "lala"));
* menuItems.add(new Message(1, "1234553229", "Hi Oakis", 0, "lala"));
*/
adap = new EfficientAdapter(this, menuItems);
ListView lv = getListView();
// Creating a button - Load More
Button btnLoadMore = new Button(this);
btnLoadMore.setText("Load More");
btnLoadMore.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// Starting a new async task
// CharSequence text = "Ok dude you pressed me ";
// Toast toast = Toast.makeText(getApplicationContext(), text,
// Toast.LENGTH_SHORT);
// toast.show();
new loadMoreListView().execute();
}
});
// Adding button to listview at footer
lv.addFooterView(btnLoadMore);
setListAdapter(adap);
// adap = new ListViewAdapter(this, messages);
lv.setAdapter(adap);
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
// TODO Auto-generated method stub
super.onListItemClick(l, v, position, id);
Toast.makeText(this, "Click-" + String.valueOf(position),
Toast.LENGTH_SHORT).show();
}
/**
* Async Task that send a request to url Gets new list view data Appends to
* list view
* */
private class loadMoreListView extends AsyncTask<List<Message>, Void, Void> {
@Override
protected void onPreExecute() {
// Showing progress dialog before sending http request
pDialog = new ProgressDialog(UIHistoryListActivity.this);
pDialog.setMessage("Please wait..");
pDialog.setIndeterminate(true);
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(List<Message>... params) {
// TODO Auto-generated method stub
// UIHistoryListActivity.this
// ListView lv = getListView();
// for (Message mg : messages) {
// menuItems.add(new Message(mg.getID(), mg.getPhoneNumber(), mg
// .getBody(), mg.getStatus(), mg.getDate()));
//
// }
// setListAdapter(adap);
// adap = new ListViewAdapter(this, messages);
// lv.setAdapter(adap);
current_page = current_page + 1;
//putting the next 5 messages of my db on the list
messages = db.getMessages(index, limit);
index += limit;
limit = index + 5;
ListView lv = getListView();
for (Message mg : messages) {
menuItems.add(new Message(mg.getID(), mg.getPhoneNumber(), mg
.getBody(), mg.getStatus(), mg.getDate()));
}
//setListAdapter(adap); edw petouse exception
// adap = new ListViewAdapter(this, messages);
adap = new EfficientAdapter(UIHistoryListActivity.this, menuItems);
lv.setAdapter(adap);
// Setting new scroll position
int currentPosition = lv.getFirstVisiblePosition();
lv.setSelectionFromTop(currentPosition + 1, 0);
return null;
}
protected void onPostExecute(Void unused) {
// closing progress dialog
pDialog.dismiss();
}
}
public static class EfficientAdapter extends ArrayAdapter<Message>
implements Filterable {
private LayoutInflater mInflater;
// private Bitmap mIcon1;
private final Context context;
private final ArrayList<Message> values;
public EfficientAdapter(Context context, ArrayList<Message> values) {
// Cache the LayoutInflate to avoid asking for a new one each time.
super(context, R.layout.mycontent, 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) {
// A ViewHolder keeps references to children views to avoid
// unneccessary calls
// to findViewById() on each row.
ViewHolder holder;
// When convertView is not null, we can reuse it directly, there is
// no need
// to reinflate it. We only inflate a new View when the convertView
// supplied
// by ListView is null.
if (convertView == null) {
convertView = mInflater.inflate(R.layout.mycontent, null);
holder = new ViewHolder();
holder.body = (TextView) convertView.findViewById(R.id.body);
holder.date = (TextView) convertView.findViewById(R.id.date);
holder.from = (TextView) convertView.findViewById(R.id.from);
holder.status = (TextView) convertView
.findViewById(R.id.status);
convertView.setTag(holder);
}
else {
// Get the ViewHolder back to get fast access to the TextView
// and the ImageView.
holder = (ViewHolder) convertView.getTag();
}
convertView.setOnClickListener(new OnClickListener() {
private int pos = position;
// private String toId =
// Integer.toString(values.get(position).getId());
@Override
public void onClick(View v) {
Toast.makeText(context, "Click-" + pos, Toast.LENGTH_SHORT)
.show();
}
});
// holder.textLine.setText(TitleString[position] +
// String.valueOf(position));
holder.body.setText(getItem(position).getBody());
holder.date.setText(getItem(position).getDate());
holder.from.setText(getItem(position).getPhoneNumber());
holder.status
.setText(String.valueOf(getItem(position).getStatus()));
return convertView;
}
static class ViewHolder {
TextView from;
TextView date;
TextView body;
TextView status;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return values.size();
}
@Override
public Message 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;
}
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
db.close();
}
}
謝謝。
發表您的logcat – Nerd 2012-07-20 08:48:32
OK我編輯我的問題 – mkounal 2012-07-20 09:07:52