我已将列表项目从 BaseAdapter 转换为 ArrayAdapter ListActivity，因为我在另一个问题中被告知 ArrayAdapter 更动态且更擅长，特别是允许从列表中删除项目，然后更新以反映该删除。不过，我的 ArrayAdapter 仍然遇到同样的问题，如下所示：
我得到我的列表数据：
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);
}
使用此自定义适配器：
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;
}
}
longclicklistener 的上下文菜单提供了一个删除选项，它使用这个
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，如果 3 更改数据库
// 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;
}
上面的工作是从列表中删除一个项目，并在视觉上缩小差距。但是，当单击从中删除项目的“旧”点时（这引发了编辑所选项目的新意图），在查询数据库的新活动中引发异常（最后一行，logcat 中的 97）：
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();
用 logcat
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)
索引小于删除的列表项很好；那些具有更大索引的内容是其内容之一。我怀疑我在查询中的逻辑错误，查询不再存在的索引......但似乎我应该能够重绘列表并拥有一个反映数据库的索引列表。我真正想做的是消除列表的任何记忆，然后重新填充它，但我似乎无法做到这一点......任何帮助将不胜感激！