在 RecyclerView 中单击删除按钮时出现空点异常

Question

 public void onBindViewHolder(@NonNull final MyViewHolder myViewHolder, final int i) {
  myViewHolder.mName.setText(downModels.get(i).getName());
    myViewHolder.mDownload.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            DownloadTask();
        }
    });


myViewHolder.mDelete.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        String pdfName = downModels.get(i).getName();

        if(pdfName != null) {
            pdfName = pdfName.replace("", "")+".pdf";

            File file = new File(context.getFilesDir(), pdfName);
            try {
                if (file.exists())
                    file.delete();
                Log.e("file","file"+file.getAbsolutePath());
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

 }
});

单击“删除”按钮时，应用程序崩溃。

2020-03-01 22:50:55.461 16800-16800/com.solutions.rsaggarwal E/AndroidRuntime: FATAL EXCEPTION: main Process: com.solutions.rsaggarwal, PID: 16800 java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.File android.content.Context.getFilesDir()' on a null object reference at com.solutions.rsaggarwal.MyAdapter.onClick(MyAdapter.java:70) at android.view.View.performClick(View.java:7125) at android.view.View.performClickInternal(View.java:7102) at android.view.View.access00(View.java:801) at android.view.View$PerformClick.run(View.java:27336) at android.os.Handler.handleCallback(Handler.java:883) at android.os.Handler.dispatchMessage(Handler.java:100) at android.os.Looper.loop(Looper.java:214) at android.app.ActivityThread.main(ActivityThread.java:7356) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

Answer 1

您在适配器 class 中作为参数传递的 context 似乎为空。作为替代方案，您可以使用附加到 itemView 的上下文，如下所示。

  Context context = myViewHolder.itemView.getContext();
  File file = new File(context.getFilesDir(), pdfName);
  try {
        if (file.exists())
                 file.delete();
         Log.e("file","file"+file.getAbsolutePath());
       } catch (Exception e) {
                e.printStackTrace();
       }
    }

在 RecyclerView 中单击删除按钮时出现空点异常

Getting Null point Exception when Clicking Delete Button in RecyclerView

java

android

delete-file