Attempt to invoke virtual method 'void pdfreader.pdfconverter.pdfreaderapp.pdfAdapter.updatePdfFile(java.util.ArrayList)' on a null object reference

huangapple
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英文:

Attempt to invoke virtual method 'void pdfreader.pdfconverter.pdfreaderapp.pdfAdapter.updatePdfFile(java.util.ArrayList)' on a null object reference

问题

在我在searchView中输入文本以搜索项目时，我的应用程序崩溃了。我有一个片段和一个适配器。接下来我该怎么做？有人能帮帮我。

这是我收到的错误信息-
尝试调用空对象引用上的'void pdfreader.pdfconverter.pdfreaderapp.pdfAdapter.updatePdfFile(java.util.ArrayList)'方法

以下是片段的代码

  1. public class Pdf_Reader_fragments extends Fragment implements SearchView.OnQueryTextListener {
  3.     // ... 其他代码 ...
  5.     @Override
  6.     public boolean onQueryTextChange(String newText) {
  8.         String userInput = newText.toLowerCase();
  9.         ArrayList<File> myfile = new ArrayList<>();
  11.         for (File pdf : pdffiles){
  12.             if (pdf.getName().toLowerCase().contains(userInput)){
  13.                 myfile.add(pdf);
  14.             }
  15.         }
  17.         adapter.updatePdfFile(myfile);
  19.         return true;
  20.     }
  21. }

pdfAdapter 类

  1. public class pdfAdapter extends RecyclerView.Adapter<pdfAdapter.MyViewHolder> {
  3.     // ... 其他代码 ...
  5.     void updatePdfFile(ArrayList<File> fileArrayList){
  6.         files.clear();
  7.         files.addAll(fileArrayList);
  8.         notifyDataSetChanged();
  9.     }
  10. }

希望这些内容对您有所帮助。如果您需要更多帮助，请随时问我。

英文:

When I am typing text in searchView for search items, my app getting crashed. I have a fragment and adapter. What I do next? Someone help me.

This is the error I got-
Attempt to invoke virtual method 'void pdfreader.pdfconverter.pdfreaderapp.pdfAdapter.updatePdfFile(java.util.ArrayList)' on a null object reference

here is fragment code

  1. public class Pdf_Reader_fragments extends Fragment implements SearchView.OnQueryTextListener {
  3.     public static ArrayList&lt;File&gt; pdffiles = new ArrayList&lt;&gt;();
  5.     RecyclerView recyclerView;
  7.     File folder;
  8.     String[] items;
  9.     static pdfAdapter adapter;
  11.     int number = 0;
  13.     private SwipeRefreshLayout mSwipeRefreshLayout;
  15.     public Pdf_Reader_fragments() {
  17.     }
  20.     @Override
  21.     public View onCreateView(LayoutInflater inflater, ViewGroup container,
  22.                              Bundle savedInstanceState) {
  24.         View view = inflater.inflate(R.layout.fragment_pdf__reader, container, false);
  26.         recyclerView = (RecyclerView) view.findViewById(R.id.recylerView);
  28.         mSwipeRefreshLayout = view.findViewById(R.id.swip);
  29.         setHasOptionsMenu(true);
  30.         mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
  31.             @Override
  32.             public void onRefresh() {
  33.                 try {
  34.                     intiViews();
  35.                 } catch (Exception e) {
  37.                 }
  39.                 Toast.makeText(getContext(), &quot;Page Refresh&quot;, Toast.LENGTH_SHORT).show();
  40.                 mSwipeRefreshLayout.setRefreshing(false);
  43.             }
  44.         });
  46.         intiViews();
  47.         return view;
  48.     }
  51.     private void intiViews() {
  52.         folder = new File(Environment.getExternalStorageDirectory().getAbsolutePath());
  53.         pdffiles = getPdfFiles(folder);
  55.         ArrayList&lt;File&gt; mypdf = getPdfFiles(Environment.getExternalStorageDirectory());
  56.         items = new String[mypdf.size()];
  57.         for (int i = 0; i &lt; items.length; i++) {
  58.             items[i] = mypdf.get(i).getName().replace(&quot;.pdf&quot;, &quot;&quot;);
  59.         }
  60.         pdfAdapter adapter = new pdfAdapter(getContext(), pdffiles, items);
  61.         recyclerView.setAdapter(adapter);
  62.         recyclerView.setLayoutManager(new LinearLayoutManager(getActivity(), RecyclerView.VERTICAL, false));
  64.     }
  66.     private ArrayList&lt;File&gt; getPdfFiles(File folder) {
  67.         ArrayList&lt;File&gt; arrayList = new ArrayList&lt;&gt;();
  68.         File[] file = folder.listFiles();
  70.         if (file != null) {
  71.             for (File singleFile : file) {
  72.                 if (singleFile.isDirectory() &amp;&amp; !singleFile.isHidden()) {
  73.                     arrayList.addAll(getPdfFiles(singleFile));
  74.                 } else {
  75.                     if (singleFile.getName().endsWith(&quot;.pdf&quot;)) {
  76.                         arrayList.add(singleFile);
  77.                     }
  78.                 }
  79.             }
  80.         }
  81.         return arrayList;
  82.     }
  85.     @Override
  86.     public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
  87.         super.onCreateOptionsMenu(menu, inflater);
  88.         menu.clear();
  90.         inflater.inflate(R.menu.search, menu);
  91.         MenuItem item = menu.findItem(R.id.search_button);
  92.         item.setShowAsAction(MenuItem.SHOW_AS_ACTION_COLLAPSE_ACTION_VIEW | MenuItem.SHOW_AS_ACTION_IF_ROOM);
  94.         SearchView searchView = (SearchView) item.getActionView();
  95.         searchView.setOnQueryTextListener(this);
  96.     }
  98.     @Override
  99.     public boolean onQueryTextSubmit(String query) {
  100.         if (adapter != null) {
  102.             query = String.valueOf(query.equals(&quot;&quot;));
  103.         }
  104.         return true;
  105.     }
  107.     @Override
  108.     public boolean onQueryTextChange(String newText) {
  110.         String userInput = newText.toLowerCase();
  111.         ArrayList&lt;File&gt; myfile = new ArrayList&lt;&gt;();
  113.         for (File pdf : pdffiles){
  114.             if (pdf.getName().toLowerCase().contains(userInput)){
  115.                 myfile.add(pdf);
  116.             }
  118.             adapter.updatePdfFile(myfile);
  119.         }
  121.           return true;
  122.     }
  125.     }

pdfAdapter class

  1. public class pdfAdapter extends RecyclerView.Adapter&lt;pdfAdapter.MyViewHolder&gt; {
  2.     private Context mContext;
  3.     private ArrayList&lt;File&gt; files;
  4.    
  6.     String [] items;
  9.     public pdfAdapter(Context mContext, ArrayList&lt;File&gt; files, String[] items) {
  10.         this.mContext = mContext;
  11.         this.files = files;
  12.         this.items = items;
  13.     }
  16.     @NonNull
  17.     @Override
  18.     public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
  19.         View view = LayoutInflater.from(mContext).inflate(R.layout.pdf_items, parent, false);
  20.         return new MyViewHolder(view);
  21.     }
  23.     @Override
  24.     public void onBindViewHolder(@NonNull MyViewHolder holder, final int position) {
  25.         holder.file_name.setText(items[position]);
  27.         holder.popUpMenu.setOnClickListener(new View.OnClickListener() {
  28.             @Override
  29.             public void onClick(final View v) {
  30.                 PopupMenu popupMenu = new PopupMenu(mContext, v);
  31.                 popupMenu.getMenuInflater().inflate(R.menu.menu, popupMenu.getMenu());
  32.                 popupMenu.show();
  33.                 popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
  34.                     @Override
  35.                     public boolean onMenuItemClick(MenuItem item) {
  36.                         switch (item.getItemId()){
  37. //                            case R.id.edit:
  38. //                                Toast.makeText(mContext, &quot;Edit&quot;, Toast.LENGTH_SHORT).show();
  39. //                                break;
  40.                             case R.id.delete:
  42.                                // Toast.makeText(mContext, &quot;Delete&quot;, Toast.LENGTH_SHORT).show();
  43.                                 deleteFile(position, v);
  45.                         }
  46.                         return true;
  47.                     }
  48.                    public void deleteFile (final int position, View v) {
  50.                   String uri = files.get(position).getAbsolutePath();
  51.                           final File file = new File (uri);
  52.                        boolean deleted = file.delete();
  53.                        if (deleted) {
  54.                            files.remove(position);
  55.                            notifyItemRemoved(position);
  56.                            notifyItemRangeChanged(position, files.size());
  57.                            Toast.makeText(mContext, &quot;Delete sucessfully&quot;, Toast.LENGTH_SHORT).show();
  58.                        }
  59.                    }
  60.                 });
  63.             }
  64.         });
  65.         holder.pdf_Layouts.setOnClickListener(new View.OnClickListener() {
  66.             @Override
  67.             public void onClick(View v) {
  68.                 Intent intent = new Intent(mContext, PdfViewActivity.class);
  69.                 intent.putExtra(&quot;position&quot;, position);
  70.                 mContext.startActivity(intent);
  71.             }});
  73.     }
  75.     @Override
  76.     public int getItemCount() {
  77.         return files.size();
  78.     }
  85.     public class MyViewHolder extends RecyclerView.ViewHolder{
  87.         TextView file_name;
  88.         ImageView file_icon,popUpMenu;
  89.         RelativeLayout pdf_Layouts;
  91.         public MyViewHolder(@NonNull View itemView) {
  92.             super(itemView);
  93.             file_name = itemView.findViewById(R.id.pdf_item_name);
  94.             file_icon = itemView.findViewById(R.id.img_pdf);
  95.             pdf_Layouts = itemView.findViewById(R.id.pdf_items_h);
  96.             popUpMenu  = itemView.findViewById(R.id.more);
  98.         }
  99.     }
  101.     void updatePdfFile(ArrayList&lt;File&gt; fileArrayList){
  102. //       
  103.         files.clear();
  104.         files.addAll(fileArrayList);
  105.         notifyDataSetChanged();
  106.     }
  108. }

答案1

得分: 1

你没有将适配器分配给你的类变量 static pdfAdapter adapter;

在 private void intiViews() 函数中将：

pdfAdapter adapter = new pdfAdapter(getContext(), pdffiles, items); 替换为

adapter = new pdfAdapter(getContext(), pdffiles, items);

英文:

You are not assigning adapter to your class variable static pdfAdapter adapter;

In private void intiViews() function change:

pdfAdapter adapter = new pdfAdapter(getContext(), pdffiles, items); to

adapter = new pdfAdapter(getContext(), pdffiles, items);

huangapple
  • 本文由 发表于 2020年8月28日 13:54:20
  • 转载请务必保留本文链接：https://go.coder-hub.com/63628213.html
  • android
  • java
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