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我已經將列表項目從BaseAdapter轉換爲ArrayAdapter ListActivity，因爲我在另一個問題中被告知ArrayAdapter更具動態性和更好性，特別是允許刪除項目從列表中進行更新，然後進行更新以反映該刪除。我仍然在運行到同一個問題，我的ArrayAdapter，不過，具體如下：刪除列表項，然後查詢數據庫拋出異常
我得到我的列表數據像這樣：
public void loadAdapter(){
DatabaseHelper helper = new DatabaseHelper(ActivityMain.this);
database = helper.getReadableDatabase();
Cursor data = database.query("list_data", fields, null, null, null,
null, null);
Integer tindex = data.getColumnIndex("listTitle");
Integer iindex = data.getColumnIndex("listType");
itemCount = 0;
for (data.moveToFirst(); !data.isAfterLast(); data.moveToNext()) {
m_parts.add(new Item(data.getString(tindex), data.getString(iindex)));
itemCount++;
}
data.close();
for (int j = 0; j < 10; j++) {
m_parts.add(new Item("", "R"));
}
m_adapter = new ItemAdapter(ActivityMain.this, R.layout.listview, m_parts);
setListAdapter(m_adapter);
}
與此自定義適配器：
public class ItemAdapter extends ArrayAdapter<Item> {
private ArrayList<Item> objects;
public ItemAdapter(Context context, int textViewResourceId,
ArrayList<Item> objects) {
super(context, textViewResourceId, objects);
this.objects = objects;
}
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater inflater = (LayoutInflater) getContext()
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = inflater.inflate(R.layout.listview, null);
}
Item i = objects.get(position);
if (i != null) {
TextView textview = (TextView) v.findViewById(R.id.tv_main);
ImageView imageview = (ImageView) v.findViewById(R.id.iv_main);
TextView textview2 = (TextView) v.findViewById(R.id.tv_main2);
textview.setText(i.getText());
textview2.setText(i.getText());
imageview.setScaleType(ScaleType.FIT_XY);
Integer theDrawable;
if (i.getImage() != "L") {
theDrawable = R.drawable.listview_regular;
} else {
theDrawable = R.drawable.listview_location;
}
imageview.setImageResource(theDrawable);
}
v.setOnClickListener(new OnItemClickListener(position));
v.setOnLongClickListener(new OnItemLongClickListener(position));
return v;
}
}
的來自longclicklistener的上下文菜單提供刪除選項，其使用此
private void showDialogOnLongClick(final int position) {
Builder alert = new AlertDialog.Builder(this);
ArrayList<String> listInfo = getListInfo(position);
String content = listInfo.get(1);
String numItems = "";
if (content != null && content.indexOf("|~|") > -1) {
String[] contentSplit = content.split("\\|\\~\\|");
numItems = contentSplit.length + " items in list";
} else {
numItems = "No items in list";
}
String listTitle = listInfo.get(0);
String created = "Created: " + listInfo.get(2);
String modified = "Modified: " + listInfo.get(3);
String delete = "Delete";
String edit = "Edit";
final String[] items = new String[] { created, modified, numItems,
delete, edit };
alert.setTitle(listTitle);
alert.setItems(items, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
switch (which) {
case 3:
if (deleteList(position)) {
//listview.invalidate();
//Item itemToRemove = m_parts.remove(position);
//m_adapter.remove(itemToRemove);
//m_adapter.remove(toRemove);
//m_adapter.notifyDataSetInvalidated(); <-- These are all things I've tried
//m_adapter.clear(); in various combinations
//m_adapter.remove(position);
Item toRemove = m_adapter.getItem(position);
m_parts.remove(toRemove); //or, m_parts.remove(position);<-This is what should work
m_adapter.notifyDataSetChanged();
loadAdapter();
// runOnUiThread(new Runnable() {
// public void run() {
// m_adapter.notifyDataSetChanged(); <--I've tried a thread approach
// }
// });
}
break;
case 4:
Intent i = new Intent(ActivityMain.this,
ShowARegularList.class);
i.putExtra("list_id", (position + 1) + "");
startActivity(i);
break;
}
}
});
alert.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
alert.show();
}
其中，在3變化與
// Delete single list item data
public boolean deleteList(int id) {
id++;
DatabaseHelper helper = new DatabaseHelper(this);
database = helper.getWritableDatabase();
// ContentValues values = new ContentValues();
// values.put("_id", id);
database.delete("list_data", "_id =" + id, null);
database.close();
// text = text.removeElementStr();
// itemCount--;
return true;
}
上述作品數據庫以從列表中刪除的項目，並且在視覺上封閉間隙。但是，當點擊刪除項目的「舊」點（這引發了編輯所選項目的新意圖）時，在查詢db的新活動（logcat中的最後一行，97）中引發了一個異常：
final Integer thisListID = Integer.parseInt(listIDstr);
final DatabaseHelper helper = new DatabaseHelper(this);
database = helper.getReadableDatabase();
Cursor cursor = database.query("list_data", new String[] { "listTitle",
"listContent", "dateCreated", "dateModified" }, "_id = " + thisListID
+ "", null, null, null, null);
ArrayList<String> listInfo = new ArrayList<String>();
if (cursor != null && cursor.moveToFirst()) {
listInfo.add(cursor.getString(cursor.getColumnIndex("listTitle")));
listInfo.add(cursor.getString(cursor.getColumnIndex("listContent")));
listInfo.add(cursor.getString(cursor.getColumnIndex("dateCreated")));
listInfo.add(cursor.getString(cursor.getColumnIndex("dateModified")));
}
cursor.close();
strListContent = listInfo.get(1).trim();
與logcat的
java.lang.RuntimeException: Unable to start activity...
java.lang.IndexOutOfBoundsException: Invalid index 1, size is 0
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2049)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2083)
at android.app.ActivityThread.access$600(ActivityThread.java:134)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1233)
...
at com.baked.listanywhere.ShowARegularList.onCreate(ShowARegularList.java:97)
索引列表項小於刪除一個的罰款;那些索引較大的人在其內容中只有一個。我懷疑我的查詢邏輯錯誤，查詢不存在的索引......但似乎我應該可以重新繪製列表並且有一個反映數據庫的索引列表。我真正想做的是消除名單上的任何記憶，然後重新填充它，但我似乎無法做到這一點...任何幫助將不勝感激！
我的想法在這一點上：因爲我查詢的主鍵不再存在 - 我可以用rownum查詢（沒有工作）;或創建一個臨時表，將值加載到它中，並檢索第n行......看起來像一個kludge;有任何想法嗎？ – kwishnu