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我正在嘗試在Android中使用SQLite數據庫進行CRUD操作以獲取列表視圖。我正在使用片段，活動和自定義基礎適配器。我可以成功突出顯示，刪除或編輯項目，並更新列表視圖和適配器。Android：在刪除操作後查看ListView項目視圖刪除項目
當我刪除一個項目（列表視圖和適配器已更新）時遇到問題，然後嘗試選擇並突出顯示後面的項目。編輯操作引用了最近刪除的項目。當我刪除一個項目並重新加載活動時，一切都按預期工作。
這使我相信列表視圖刷新和數據庫操作按預期工作，但適配器在刪除後不更新。也許這與我將它傳遞給持久高亮目的所選位置的方式有關。
代碼如下。請讓我知道，如果你需要我張貼更多或有任何改進意見的建議。
ChampionListFragment.java（我們的主列表視圖）
`
package com.androidtitan.trooptracker.Fragment;
import android.app.Activity;
import android.app.Fragment;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import com.androidtitan.alphaarmyapp.R;
import com.androidtitan.trooptracker.Adapter.ChampionAdapter;
import com.androidtitan.trooptracker.Data.DatabaseHelper;
import com.androidtitan.trooptracker.Data.Division;
import com.androidtitan.trooptracker.Data.Soldier;
import com.androidtitan.trooptracker.Interface.ChampionDataPullInterface;
import com.androidtitan.trooptracker.Interface.ChampionInterface;
import java.util.ArrayList;
import java.util.List;
public class ChampionListFragment extends Fragment {
DatabaseHelper databaseHelper;
ChampionInterface championInterface;
ChampionDataPullInterface pullInterface;
ImageView deleter;
ImageView editer;
ImageView adder;
TextView proceedBtn; //this will "slide" the fragment to
TextView championHeader;
ChampionAdapter adapter;
ListView listView;
Division focusDivision;
Soldier focusSoldier;
ArrayList<Soldier> soldierItems;
List<Soldier> troops;
int selection = -1;
public int receivedIndex = -1;
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
championInterface = (ChampionInterface) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnFragmentInteractionListener");
}
try {
pullInterface = (ChampionDataPullInterface) activity;
} catch(ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement MainDataPullInterface");
}
receivedIndex = pullInterface.getDivisionIndex();
}
public ChampionListFragment() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if(savedInstanceState != null) {
}
databaseHelper = DatabaseHelper.getInstance(getActivity());
soldierItems = new ArrayList<Soldier>();
troops = databaseHelper.getAllSoldiersByDivision(databaseHelper.getAllDivisions().get(receivedIndex));
soldierItems.addAll(troops);
Runnable runnable = new Runnable() {
@Override
public void run() {
adapter.notifyDataSetChanged();
listView.invalidateViews();
}
};
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_listview_champion, container, false);
deleter = (ImageView) getActivity().findViewById(R.id.deleteBtn);
editer = (ImageView) getActivity().findViewById(R.id.editBtn);
adder = (ImageView) getActivity().findViewById(R.id.addBtn);
championHeader = (TextView) v.findViewById(R.id.championHeader);
championHeader.setText(databaseHelper.getAllDivisions().get(receivedIndex).getName());
listView = (ListView) v.findViewById(R.id.championList);
adapter = new ChampionAdapter(getActivity(), getListItems());
listView.setAdapter(adapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
if (!troops.get(position).isSelected()) {
troops.get(position).setIsSelected(true);
if (selection != -1) {
troops.get(selection).setIsSelected(false);
}
selection = position;
championInterface.setListViewSelection(selection);
}
else {
troops.get(position).setIsSelected(false);
selection = -1;
listView.invalidateViews();
championInterface.setListViewSelection(-1);
}
for (int i = 0; i <= listView.getLastVisiblePosition() - listView.getFirstVisiblePosition(); i++) {
View item = listView.getChildAt(i);
item.setBackgroundColor(0xFFFFFFFF);
}
view.setBackgroundColor(0xCC448AFF);
Log.e("CLFonItemClick", troops.get(position).getfName() + " " + troops.get(position).isSelected());
}
});
deleter.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(selection != -1) {
focusDivision = databaseHelper.getAllDivisions().get(receivedIndex);
focusSoldier = databaseHelper.getAllSoldiersByDivision(focusDivision).get(selection);
for(Soldier s : troops) {
s.setIsSelected(false);
}
databaseHelper.deleteSoldier(focusSoldier);
adapter.removeItem(selection);
selection = -1;
Log.e("CLFdeleter", "selection: " + String.valueOf(selection));
championInterface.setListViewSelection(-1);
}
}
});
editer.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.e("CFLediter", "selection: " + String.valueOf(selection));
if(selection != -1) {
//this will populate our Adder Fragment
focusSoldier = soldierItems.get(selection);
for(Soldier s : troops) {
s.setIsSelected(false);
}
championInterface.soldierPasser(selection, receivedIndex,
focusSoldier.getfName(),
focusSoldier.getlName());
}
}
});
adder.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(selection != -1) {
focusSoldier = soldierItems.get(selection);
focusSoldier.setIsSelected(false);
}
//when we receive our divIndex then that is what we will pass into this method
championInterface.soldierPasser(selection, receivedIndex, null, null);
}
});
return v;
}
@Override
public void onDetach() {
super.onDetach();
championInterface = null;
}
private List<Soldier> getListItems() {
ArrayList<Soldier> soldierItems = new ArrayList<Soldier>();
if (receivedIndex == -1) {
soldierItems.addAll(databaseHelper.getAllSoldiers());
} else {
soldierItems.addAll(databaseHelper.getAllSoldiersByDivision(databaseHelper.getAllDivisions().get(receivedIndex)));
}
return soldierItems;
}
} `
ChampionActivity.java
`包com.androidtitan.trooptracker.Activity;
import android.app.FragmentTransaction;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import com.androidtitan.alphaarmyapp.R;
import com.androidtitan.trooptracker.Fragment.ChampionListFragment;
import com.androidtitan.trooptracker.Interface.ChampionInterface;
import com.androidtitan.trooptracker.Interface.ChampionDataPullInterface;
public class ChampionActivity extends AppCompatActivity implements ChampionDataPullInterface, ChampionInterface{
ChampionListFragment championFragment;
//ChampionDataPullInterface push4frag2pull;
int divisionIndex;
int selectionIndex = - 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_champion);
//Data Section
Intent intent = getIntent();
divisionIndex = intent.getIntExtra("landingDivision", -1);
Log.e("ChampAonCreate", "divisionIndex: " + divisionIndex);
Bundle args = new Bundle();
args.putInt("num", divisionIndex);
//View Section
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayShowTitleEnabled(false);
championFragment = new ChampionListFragment();
championFragment.setArguments(args);
FragmentTransaction fragTran = getFragmentManager().beginTransaction();
fragTran.replace(R.id.championContainer, championFragment, "championFragment").commit();
}
@Override
public void tabInteraction(int id) {
}
@Override
public void soldierPasser(int soldierInt, int divisionInt, String first, String last) {
Log.e("CAdeleter", "selection " + String.valueOf(soldierInt));
Intent intent = new Intent(this, AdderActivity.class);
intent.putExtra("editSoloIndex", soldierInt);
intent.putExtra("editSoloDivIndex", divisionInt);
intent.putExtra("editSoloFirst", first);
intent.putExtra("editSoloLast", last);
startActivity(intent);
}
//this is going to be once we have more fragments such as maps and what's nearby
@Override
public void drawerListViewSelection(int selection) {
}
@Override
public void adderFragDivReference(int divIndex) {
Intent intent = new Intent(this, AdderActivity.class);
intent.putExtra("divIndex", divIndex);
ChampionActivity.this.finish();
startActivity(intent);
}
@Override
public void setListViewSelection(int selection) {
selectionIndex = selection;
}
public int getListViewSelection() {
return selectionIndex;
}
@Override
public int getDivisionIndex() {
return divisionIndex;
}
@Override
public void onBackPressed() {
Intent intent = new Intent(this, LandingActivity.class);
this.finish();
startActivity(intent);
}
} `
ChampionAdapter.java
`
package com.androidtitan.trooptracker.Adapter;
import android.app.Activity;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import com.androidtitan.alphaarmyapp.R;
import com.androidtitan.trooptracker.Activity.ChampionActivity;
import com.androidtitan.trooptracker.Data.DatabaseHelper;
import com.androidtitan.trooptracker.Data.Soldier;
import java.util.List;
/**
* Created by amohnacs on 6/19/15.
*/
/*
todo: we need to take the implementation of highlighting our listview items in the adapter form ADDERFRAGMENT
todo: and implement them in the getView here.
todo: We might have to deal with passing the 'oldDivision' and 'divSelected' variables
todo: maybe create some headers.
*/
public class ChampionAdapter extends BaseAdapter {
private Activity context;
DatabaseHelper databaseHelper;
private List<Soldier> adapterData;
private LayoutInflater layoutInflater;
private int selection = -1;
public ChampionAdapter(Activity acontext, List<Soldier> soldiers) {
this.context = acontext;
this.adapterData = soldiers;
layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
databaseHelper = DatabaseHelper.getInstance(context);
}
@Override
public int getCount() {
return adapterData.size();
}
@Override
public Object getItem(int position) {
return adapterData.get(position);
}
@Override
public long getItemId(int position) {
return adapterData.get(position).getId();
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ListViewHolder viewHolder;
selection = ((ChampionActivity) context).getListViewSelection();
if(convertView == null) {
//inflate the listview_item_row.xml
LayoutInflater li = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = li.inflate(R.layout.listview_champion_item, null);
viewHolder = new ListViewHolder();
convertView.setTag(viewHolder);
viewHolder.firstItem = (TextView) convertView.findViewById(R.id.champ_text);
}
else {
viewHolder = (ListViewHolder) convertView.getTag();
}
//ListViewSelection
if (position == selection) {
convertView.setBackgroundColor(0xCC448AFF);
}
else {
convertView.setBackgroundColor(0xFFFFFFFF);
}
viewHolder.firstItem.setText(adapterData.get(position).getfName() + " "
+ adapterData.get(position).getlName());
Log.e("CLFonItemClick", adapterData.get(position).getfName() + " " + adapterData.get(position).isSelected());
return convertView;
}
class ListViewHolder {
public TextView firstItem;
}
public void removeItem(int itemPosition) {
//Remove the according group. Dont forget to remove the children aswell!
adapterData.remove(itemPosition);
notifyDataSetChanged();
notifyDataSetInvalidated();
}
}`
ChampionInterface.java
`
public interface ChampionInterface {
public void tabInteraction(int id);
public void soldierPasser(int soldierInt, int divisionInt, String first, String last);
public void drawerListViewSelection(int selection);
public void adderFragDivReference(int divIndex);
public void setListViewSelection(int selection);
}
`
你的數據模型是sqlite數據庫，那麼你爲什麼使用BaseAdapter？請使用SimpleCursorAdapter，請參閱Notepatd演示：http：//developer.android.com/training/notepad/index.html，您將看到您的生活如何變得更加輕鬆... – pskink
謝謝！遊標適配器絕對可以讓所有事情變得更加清潔。問題依然存在。這是因爲我的數據庫只在我的片段的onCreate（）方法上更新，當它需要通過onClick（）操作更新表時。 – androidtitan
http://developer.android.com/training/notepad/notepad-ex2.html^F第3步 – pskink