ArrayList 大小增加每个 onCreateView 调用

Question

我在Fragment 中有RecyclerView，我正在从Sqlite 填充ArrayList，并且有一个Form 可以让我将条目添加到数据库中。那么会出现什么问题呢？

在我添加任何新条目之前它工作正常，但是当我通过表单添加新条目时，它会重定向回RecyclerView's Fragment，而不显示任何新添加的条目。当我再次按下按钮添加条目并返回而不通过按下 返回按钮 将任何条目添加到表单中时，它会显示新条目并复制以前的条目。我不知道我哪里出错了，我已经尝试过解决问题但无法解决这个问题。

这是我的fragment，我有RecyclerView

public class fragment_1 extends Fragment {

    CRUD_database db;
    SQLiteDatabase sqLiteDatabase;
    RecyclerView mRecyclerView;
    RecyclerView.Adapter adapter;
    RecyclerView.LayoutManager layoutManager;
    static List<PPL_list_wrapper> Loc_details=new ArrayList<PPL_list_wrapper>();
    FloatingActionButton fab;
    PPL_list_wrapper PPL_wrapper;
    int ID;
    ArrayList<PPL_list_wrapper> list=new ArrayList<>();
    public static final String TAG="====Fragment_1====";
    String name,title,address,passing_year,description;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view=inflater.inflate(R.layout.fragment_fragment_1, container, false);
        TextView textView= (TextView) view.findViewById(R.id.listNULL);
        mRecyclerView= (RecyclerView) view.findViewById(R.id.ppl_RecyclerView);
        layoutManager=new LinearLayoutManager(getActivity());
        mRecyclerView.setLayoutManager(layoutManager);
        adapter=new ppl_Recycler_Adapter(getActivity(),list);
        mRecyclerView.setAdapter(adapter);


        fab= (FloatingActionButton) view.findViewById(R.id.PPL_fab_Add_PPL);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                FragmentTransaction fragmentTransaction=getFragmentManager().beginTransaction();
                Add_PPL add_ppl=new Add_PPL(); //This Fragment Has Form To Add Entry into Database
                fragmentTransaction.replace(R.id.Navigation_Main_Layout,add_ppl);
                fragmentTransaction.addToBackStack(null);
                fragmentTransaction.commit();
            }
        });

        Log.d(TAG,"Value of Context Oncreate "+" Value of GetActivity"+" "+getActivity());
        db=new CRUD_database(getActivity());
        Cursor cursor=db.getALL_PPL();
            Log.d(TAG,"Cursor Position To First :"+cursor.moveToFirst());
            Log.d(TAG,"Cursor and List Value :"+"Cursor: "+cursor.getCount()+" "+"List: "+list.size());
            if (cursor.moveToFirst()&& !(list.size()==cursor.getCount())){   // This Condition to avoid Array to increase its size as soon as database has new row it will call 
               do{

                        Log.d(TAG,"Cursor Position: "+cursor.getColumnCount()+" "+"Value of Rows "+cursor.getCount());
                        ID=cursor.getInt(cursor.getColumnIndex("_ID"));
                        name=cursor.getString(cursor.getColumnIndex("PPL_NAME"));
                        title=cursor.getString(cursor.getColumnIndex("PPL_TITLE"));
                        address=cursor.getString(cursor.getColumnIndex("PPL_ADDRESS"));
                        passing_year=cursor.getString(cursor.getColumnIndex("PPL_TIME"));
                        description=cursor.getString(cursor.getColumnIndex("PPL_DESCRIPTION"));

                        Log.d(TAG,title+" "+address+" "+ passing_year+" "+description+" "+ID);
                        PPL_list_wrapper fromDatabase=new PPL_list_wrapper(ID,title,name,passing_year,address);
                        list.add(fromDatabase);
                        adapter=new ppl_Recycler_Adapter(getActivity(),list);
                       // adapter.notifyItemChanged(cursor.getCount());

                }
               while (cursor.moveToNext());
                adapter.notifyItemChanged(cursor.getCount());
                cursor.close();
            }
        else if (cursor.getColumnCount()==0 || list.size()==0){
                textView.setText("NO RECORD FOUND");
            }

        return view;
    }

所以我的问题是，在从Fragment 回到RecyclerView Fragment 后，如何避免Arraylist 以增加其大小？

每当每次调用RecyclerView Fragment's onCreateView 时，我如何从数据库中获取完整的行。

Answer 1

添加

list.clear();

从 db 获得 cursor 之后。

Answer 2

你必须在OnCreateView

中初始化

list=new ArrayList<>();