NullPointerException using constructor of `File` class (only on Samsung A series devices) in my application [duplicate]

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I have an application published on the Play Store (Google Play). For months now, I have been receiving an error in my console. First of all, here is the relevant code from my application:

MainActivity

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

    //get storage directories
    rutasTemp = getStorageDirectoriesWithoutNull(this);
    int indexTemp = 0;
    for (String s : rutasTemp) {
        if (!(s.contains("usb"))) {
            indexTemp++;
        }
    }
    if (externalMemoryAvailable(this)) {
        rutas = new String[indexTemp];
        indexTemp = 0;
        for (String s : rutasTemp) {
            if (!(s.contains("usb"))) {
                rutas[indexTemp] = s;
                indexTemp++;
            }
        }
        for (int i=0; i<rutas.length; i++) {
            if (rutas[i].contains("emulated")) {
                String temp = rutas[0];
                rutas[0] = rutas[i];
                rutas[i] = temp;
            }
        }
    } else {
        rutas = new String[1];
        rutas[0] = Environment.getExternalStorageDirectory()
            .getAbsolutePath() + "/";

    }

    //more code

    carpetasPreferences = getSharedPreferences(SHARED_CARPETAS, Context.MODE_PRIVATE);
}


private void prepararPlayer(int desdeDonde) {

    //more code

    Map<String, ?> carpetasMap = carpetasPreferences.getAll();
    String[] carpetasArray = null;
    carpetasArray = new String[carpetasMap.size()];
    int indice = 0;
    for (Map.Entry<String, ?> asno: carpetasMap.entrySet()) {
        carpetasArray[indice] = asno.getValue().toString() + "/";
        indice++;
    }
    if (carpetasMap.size() == 0) {
        if (notClickedOnce) {
            carpetasArray = new String[rutas.length];
            //button pressed first time
            carpetasArray[0] = Environment.getExternalStorageDirectory()
                .getAbsolutePath() + "/Music/";
            if (rutas.length > 1) {
                carpetasArray[1] = rutas[1];
            }
        }
    }

    if (desdeDonde == 0) {
        if (sharedPreferences.contains(LIST_OF_FILES)) {
            nombresArchivo = sharedPreferences.getStringSet(LIST_OF_FILES, new HashSet<String>());
        } else {
            buscarArchivos = new BuscarArchivos(this, carpetasArray, nombresArchivo, desdeDonde);
            buscarArchivos.execute();
        }
    } else {
        buscarArchivos = new BuscarArchivos(this, carpetasArray, nombresArchivo, desdeDonde);
        buscarArchivos.execute();
    }
        
    //more code
}


private static class BuscarArchivos extends AsyncTask<Void, Void, String> {
    WeakReference<MainActivity> activityReference;
    String[] carpetasArray;
    Set<String> nombArch;
    int desdeDonde;
    BuscarArchivos(MainActivity activity, String[] carpetasArray, Set<String> nombresArchivo, 
        int desdeDonde) {
            this.activityReference = new WeakReference<>(activity);
            this.carpetasArray = carpetasArray;
            this.nombArch = nombresArchivo;
            this.desdeDonde = desdeDonde;
    }
    @Override
    protected String doInBackground(Void... voids) {
        try {
            for (String asn : carpetasArray) {
                activityReference.get().listAllFiles(asn, nombArch);
            }                   
            activityReference.get().sharedPreferencesEditor
                .putStringSet(activityReference.get()
                .LIST_OF_FILES, nombArch);
            activityReference.get().sharedPreferencesEditor.apply();
        } catch (Exception e) {
            Writer writer = new StringWriter();
            e.printStackTrace(new PrintWriter(writer));
            return writer.toString();
        }
        return "final";
    }
        
    //rest of the code of BuscarArchivos
}

public void listAllFiles(String rutaAdentro, Set<String> archivos) {
    File file = new File(rutaAdentro);
    File[] files = file.listFiles();
    if (files != null) {
        for (File asno : files) {
            if (asno.isFile()) {
                archivos.add(asno.getName());
            } else if (asno.isDirectory()) {
                listAllFiles(asno.getAbsolutePath(), archivos);
            }
        }
    }
}

private String[] getStorageDirectoriesWithoutNull(Context context) {
    String[] allDirectories = StorageUtil
        .getStorageDirectories(context);
    ArrayList<String> directoriesList = new ArrayList<>();
    for (String directory : allDirectories) {
        if (directory != null) {
            directoriesList.add(directory);
        }
    }
    return directoriesList.toArray(new String[0]);
}

I’m using the library StorageUtil by hendrawd (https://github.com/hendrawd/StorageUtil) in the getStorageDirectoriesWithoutNull method.

The following is the adapter used in the activity in which a select music folders:

Adapter

public Adaptador(Context contextInside, int layoutIdInside, ArrayList<HashMap<String, 
    String>> listaInside, String rutaInside) {

        //more code
        
        carpetasPreferences = getContext().getSharedPreferences(SHARED_CARPETAS, Context.MODE_PRIVATE);
        carpetasPreferencesEditor = carpetasPreferences.edit();
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    //more code

    checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
            if (b) {
                carpetasPreferencesEditor.putString(elemento.get(PATH), elemento.get(PATH));
                carpetasPreferencesEditor.apply();
            } else {
                if (carpetasPreferences.contains(elemento.get(PATH))) {
                    carpetasPreferencesEditor.remove(elemento.get(PATH));
                    carpetasPreferencesEditor.apply();
                }
            }
            if (carpetasPreferences.contains(ruta)) {
                carpetasPreferencesEditor.remove(ruta);
                carpetasPreferencesEditor.apply();
            }
        }
    });
       
    //rest of the code
}

I hope I’ve included all the relevant code. If I’ve forgotten something, I’d appreciate it if you let me know.

I’m having the following error in my google play console:

    java.lang.NullPointerException
    at java.io.File.<init>(File.java:283)
    at gym.timer.app.MainActivity.listAllFiles(MainActivity.java:3093)
    at gym.timer.app.MainActivity$BuscarArchivos.doInBackground(MainActivity.java:3133)
    at gym.timer.app.MainActivity$BuscarArchivos.doInBackground(MainActivity.java:3118)
    at android.os.AsyncTask$3.call(AsyncTask.java:394)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:305)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
    at java.lang.Thread.run(Thread.java:923)

As you can see, I’m having a NullPointerException in the line: File[] files = file.listFiles();.
The application works well on almost all devices, but I am experiencing errors on a few devices, specifically/only on Samsung A series devices. Below, I list the models of the devices:

error SM-A217M sdk 31
error SM-A127M sdk 30
error SM-A305G sdk 30
error SM-A505G sdk 30
error SM-A307G sdk 30
error SM-A505G sdk 30
error SM-A105M sdk 30
error SM-A307G sdk 29
error SM-A305G sdk 30
error SM-A217F sdk 30
error SM-A127M sdk 33

I hope someone can help me. Thank you.

I bought a smartphone, specifically the ‘SM-A307G,’ which is one of the models where the error appears, just to be able to reproduce the error. I formatted it, installed the application, but no error appears; it works normally. What I wanted was to reproduce the error, but no error appeared.

  • 1

    Your error is in the constructor of class java.io.File. Looks like you are passing a null parameter when you call the constructor, i.e. rutaAdentro is null – which means that carpetasArray contains a null. So I suggest that you debug your code and try to discover why an element in carpetasArray is null. Hint: all elements in an array are implicitly initialized to null. How are you assigning a value to carpetasArray? Are you doing new String[]?

    – 

  • This if statement (in method prepararPlayer of MainActivity) may be the problem: if (rutas.length > 1) {. My guess is that rutas[1] is null.

    – 

  • @Abra Yes, I’m using: carpetasArray = new String[carpetasMap.size()]. Is in the code.

    – 

  • 1

    Rubbish. Your original title, obtained via copy and paste from the edit history, was “NullPointerException using method listFiles() of File class”. That was imprecise, I added precision, correcting it to provide the actual problem site. You then removed that precision and whatever original precision there may have been, in favour of waffle about Google Play. This is pointless. It won’t help anybody. Imprecision didn’t help you in the first place: if you had looked at the stack trace more carefully you would have seen where the problem was for yourself, instead of having to post here.

    – 

  • 1

    It is entirely irrelevant that your app is published in Google Play.

    – 

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