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我是Android開發人員中的新成員，因此我還沒有掌握所有基礎知識。
自我幾天以來，我一直在困擾我的問題。
我的問題如下：
我得到了裏面的一些項目recyclerview。我創建了一個按鈕在列表中添加新項目。添加函數工作正常，我可以看到任何新項目，但如果我滑動到第三個片段（我的應用程序中有3個片段，並且recyclerView位於左側），或者如果我簡單地殺掉我的應用程序並重新啓動它，物品被銷燬。
所以基本上我不知道如何在android應用程序中真正保存這種東西。我需要你的幫助來向我展示。
這裏是我的代碼：如何在RecyclerView中保存更改
片段與recyclerview
public class CameraFragment extends Fragment {
//matchselector reclycler view
private ArrayList<Item> items = new ArrayList<>();
private RecyclerView recyclerView;
private SnapRecyclerAdapter adapter;
// add
private View addMatch;
private AlertDialog.Builder alertDialog;
private EditText team1_add;
private View view;
private boolean add = false;
private int edit_position;
private Item newitem;
public static CameraFragment create() {
return new CameraFragment();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_camera, container, false);
initDialog();
return view;
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
//match selector vertical recycler view
recyclerView = (RecyclerView) view.findViewById(R.id.recycler_view);
addMatch = (View) view.findViewById(R.id.add_match);
/**
* Center snapping
*/
SnapHelper snapHelper = new LinearSnapHelper();
snapHelper.attachToRecyclerView(recyclerView);
final CustomLinearLayoutManager mCustomLinearLayoutManager = new CustomLinearLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false);
recyclerView.setLayoutManager(mCustomLinearLayoutManager);
recyclerView.setHasFixedSize(true);
adapter = new SnapRecyclerAdapter(getContext(), items);
recyclerView.setAdapter(adapter);
MatchList();
adapter.notifyDataSetChanged();
//Button addmatch click
addMatch.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
switch (v.getId()){
case R.id.add_match:
removeView();
add = true;
alertDialog.setTitle("Ajout");
team1_add.setText("");
alertDialog.show();
break;
}
}
});
}
// dialog ajout
private void initDialog(){
alertDialog = new AlertDialog.Builder(getContext());
view = getActivity().getLayoutInflater().inflate(R.layout.dialog_layout_addmatch,null);
alertDialog.setView(view);
alertDialog.setPositiveButton("Ajouter", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if(add){
add =false;
newitem = new Item(5, team1_add.getText().toString(), "0", "0","0" , "0" , R.mipmap.ic_blasonvierge, R.mipmap.ic_blasonvierge);
adapter.addItem(newitem);
dialog.dismiss();
} else {
items.set(edit_position, newitem);
adapter.notifyDataSetChanged();
dialog.dismiss();
}
}
});
team1_add = (EditText)view.findViewById(R.id.team1_add);
}
private void removeView(){
if(view.getParent()!=null) {
((ViewGroup) view.getParent()).removeView(view);
}
}
public void MatchList() {
items.add(new Item(1, "a", "b", "c","d" , "12:30" , R.mipmap.ic_blasonvierge, R.mipmap.ic_blasonvierge));
items.add(new Item(4, "a", "b", "c","d" , "12:30" , R.mipmap.ic_blasonvierge, R.mipmap.ic_blasonvierge));
items.add(new Item(2, "a", "b", "c", "d" , "12:30" , R.mipmap.ic_blasonvierge, R.mipmap.ic_blasonvierge));
items.add(new Item(3, "a", "b", "c","d" , "12:30" , R.mipmap.ic_blasonvierge, R.mipmap.ic_blasonvierge));
adapter.notifyDataSetChanged();
}
}
SnapRecyclerAdapter：
public class SnapRecyclerAdapter extends RecyclerView.Adapter<SnapRecyclerAdapter.RecyclerViewHolder> {
private LayoutInflater layoutInflater;
private Context context;
private ArrayList<Item> items;
public SnapRecyclerAdapter(Context context, ArrayList<Item> items) {
this.layoutInflater = LayoutInflater.from(context);
this.context = context;
this.items = items;
}
@Override
public RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View item = layoutInflater.inflate(R.layout.item_recycler_view, parent, false);
return new RecyclerViewHolder(item);
}
@Override
public void onBindViewHolder(final RecyclerViewHolder holder, int position) {
Item item = items.get(position);
holder.Logoteam1.setImageResource(item.getLogoteam1());
holder.Logoteam2.setImageResource(item.getLogoteam2());
holder.team1.setText(item.getTeam1());
holder.team2.setText(item.getTeam2());
holder.categorie.setText(item.getCategorie());
holder.location.setText(item.getLocation());
holder.date.setText(item.getDate());
}
public void addItem(Item newitem) {
items.add(newitem);
notifyItemInserted(items.size());
notifyDataSetChanged();
}
public void removeItem(int position) {
items.remove(position);
notifyItemRemoved(position);
notifyItemRangeChanged(position, items.size());
}
@Override
public int getItemCount() {
return items.size();
}
class RecyclerViewHolder extends RecyclerView.ViewHolder {
private ImageView Logoteam1;
private ImageView Logoteam2;
private TextView team1;
private TextView team2;
private TextView categorie;
private TextView location;
private TextView date;
private RecyclerViewHolder(final View v) {
super(v);
Logoteam1 = (ImageView) v.findViewById(R.id.Logoteam1);
Logoteam2 = (ImageView) v.findViewById(R.id.Logoteam2);
team1 = (TextView) v.findViewById(R.id.team1);
team2 = (TextView) v.findViewById(R.id.team2);
categorie = (TextView) v.findViewById(R.id.categorie);
location = (TextView) v.findViewById(R.id.location);
date = (TextView) v.findViewById(R.id.date);
}
}
}
我不關注，你想如何在onDestroy之後保存它們？你知道這些物體是保存在記憶中的嗎？糾正我，如果我錯了，但我沒有看到任何持久的方式來保存數據（db，sharedprefs，存儲等）。 –
我認爲你需要以某種方式堅持你的數據。您有幾個選項 - 共享首選項，文件系統上的文件和一些數據庫。解釋它們將是相當長的任務，所以我建議您閱讀「數據存儲指南」 - https://developer.android.com/guide/topics/data/data-storage.html – stan0