Вылетает приложение при запросе доступа к хранилищу

Question

Делаю PDF Reader, но почему-то вылетает. Буду благодарен за помощь!

MainActivity.class

public class MainActivity extends AppCompatActivity {

    RecyclerView recView_pdf;
    private ArrayList<File> list_files = new ArrayList<File>();
    ArrayAdapter<File> adapter;
    File folder;
    String[] items;
    private final int REQUEST_PERMISSION = 1;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            permission();
        } else {
            initView();
        }

    }

    private void permission() {
        if(ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED
            && ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED){
           Toast.makeText(this, "Please grant permission", Toast.LENGTH_SHORT).show();

           ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.READ_EXTERNAL_STORAGE}, 1);
           ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.WRITE_EXTERNAL_STORAGE}, 2);
        } else {
            Toast.makeText(this, "You have already granted permission", Toast.LENGTH_SHORT).show();
            initView();
        }

    }

    private void initView() {
        folder = new File(Environment.getExternalStorageDirectory().getAbsolutePath());
        list_files = getPdfFiles(folder);

        ArrayList<File> list_files2 = getPdfFiles(Environment.getExternalStorageDirectory());
        items = new String[list_files2.size()];

        for(int i = 0; i < items.length; i++){
            items[i] = String.valueOf(list_files2.get(i).getName().endsWith(".pdf"));
        }

        PDFAdapter pdfAdapter = new PDFAdapter(this, list_files, items);
        recView_pdf.setAdapter(pdfAdapter);
        recView_pdf.setLayoutManager(new LinearLayoutManager(this, RecyclerView.VERTICAL, false));
    }

    private ArrayList<File> getPdfFiles(File folder) {
        ArrayList<File> list_files1 = new ArrayList<File>();
        File[] files = folder.listFiles();

        if(files != null){
            for(File itemFile : files){
                if(itemFile.isDirectory() && !itemFile.isHidden()){
                    list_files1.addAll(getPdfFiles(itemFile));
                } else {
                    if(itemFile.getName().endsWith(".pdf")){
                        list_files1.add(itemFile);
                    }
                }
            }
        }

        return list_files1;
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if(requestCode == REQUEST_PERMISSION){
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                Toast.makeText(this, "You already permission", Toast.LENGTH_SHORT).show();
                initView();
            }else{
                Toast.makeText(this, "Please press Allow to continue", Toast.LENGTH_SHORT).show();
            }
        }
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/white"
    tools:context=".MainActivity">


    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recView_pdf"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />


</androidx.constraintlayout.widget.ConstraintLayout>

PDFAdapter.class


public class PDFAdapter extends RecyclerView.Adapter<PDFAdapter.MyViewHolder> {

    private Context context;
    private ArrayList<File> list_files;
    String[] items;

    public PDFAdapter(Context context, ArrayList<File> list_files, String[] items){
        this.context = context;
        this.list_files = list_files;
        this.items = items;
    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.pdf_adapter, parent, false);

        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
        holder.textView_pdfName.setText(items[position]);
    }

    @Override
    public int getItemCount() {
        return list_files.size();
    }

    public class MyViewHolder extends RecyclerView.ViewHolder{
        TextView textView_pdfName;
        ImageView imageView_pdfIcon;

        public MyViewHolder(@NonNull View itemView) {
            super(itemView);
            textView_pdfName = itemView.findViewById(R.id.textView_pdfName);
            imageView_pdfIcon = itemView.findViewById(R.id.imageView_pdfIcon);
        }
    }
}

pdf_adapter.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <ImageView
        android:id="@+id/imageView_pdfIcon"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_margin="5dp"
        android:src="@drawable/pdf_icon"/>

    <TextView

        android:id="@+id/textView_pdfName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="File name"
        android:textSize="16dp"
        android:textColor="#353535"
        android:layout_toRightOf="@+id/imageView_pdfIcon"
        android:layout_marginLeft="20dp"
        android:maxLines="1"
        android:layout_centerVertical="true"
        android:gravity="center"
        />

</RelativeLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="wyspa.example.com.pdfreader">

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:requestLegacyExternalStorage="true"
        android:theme="@style/Theme.PDFReader">
        <activity android:name=".PDFOpener"></activity>
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Вкладка run

12/15 15:09:20: Launching 'app' on Physical Device.
App restart successful without requiring a re-install.
$ adb shell am start -n "wyspa.example.com.pdfreader/wyspa.example.com.pdfreader.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Connected to process 26584 on device 'xiaomi-mi_4-896767e3'.
Capturing and displaying logcat messages from application. This behavior can be disabled in the "Logcat output" section of the "Debugger" settings page.
W/e.com.pdfreade: Accessing hidden method Landroid/view/View;->computeFitSystemWindows(Landroid/graphics/Rect;Landroid/graphics/Rect;)Z (greylist, reflection, allowed)
W/e.com.pdfreade: Accessing hidden method Landroid/view/ViewGroup;->makeOptionalFitsSystemWindows()V (greylist, reflection, allowed)
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: wyspa.example.com.pdfreader, PID: 26584
    java.lang.RuntimeException: Unable to start activity ComponentInfo{wyspa.example.com.pdfreader/wyspa.example.com.pdfreader.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setAdapter(androidx.recyclerview.widget.RecyclerView$Adapter)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        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$MethodAndArgsCaller.run(RuntimeInit.java:491)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setAdapter(androidx.recyclerview.widget.RecyclerView$Adapter)' on a null object reference
        at wyspa.example.com.pdfreader.MainActivity.initView(MainActivity.java:75)
        at wyspa.example.com.pdfreader.MainActivity.permission(MainActivity.java:58)
        at wyspa.example.com.pdfreader.MainActivity.onCreate(MainActivity.java:42)
        at android.app.Activity.performCreate(Activity.java:7824)
        at android.app.Activity.performCreate(Activity.java:7813)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1306)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) 
        at android.os.Handler.dispatchMessage(Handler.java:107) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:7356) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:491) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

Answer 1

Если я правильно понял, то ваша ошибка выглядит так:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setAdapter(androidx.recyclerview.widget.RecyclerView$Adapter)' on a null object reference

это означает что вы пытаетесь обратится к виджету которому не присвоено какое-то значение. Делаете вы это судя по коду здесь:

recView_pdf.setAdapter(pdfAdapter);

вам нужно перед это строкой вставить такую строку:

recView_pdf = findViewById(R.id.recView_pdf);

дальше после инициализации виджета:

recView_pdf.setLayoutManager(new LinearLayoutManager(this));
recView_pdf.setAdapter(new PDFAdapter(this, list_files, items));

Так же я бы вам советовал убрать нижнее подчеркивание у наименования переменной, так как это немного противоречит правилам именования переменных в Java Naming Conventions.

БЛОГ НА HUSL

Вылетает приложение при запросе доступа к хранилищу

Ответы (1 шт):