Here's my code so far:
String path = Environment.getExternalStorageDirectory().toString()+"/Pictures";
AssetManager mgr = getAssets();
try {
String list[] = mgr.list(path);
Log.e("FILES", String.valueOf(list.length));
if (list != null)
for (int i=0; i<list.length; ++i)
{
Log.e("FILE:", path +"/"+ list[i]);
}
} catch (IOException e) {
Log.v("List error:", "can't list" + path);
}
Yet while I do have files in that dir, it returns me list.length = 0... any ideas?
This question is related to
android
Your path
is not within the assets folder. Either you enumerate files within the assets folder by means of AssetManager.list()
or you enumerate files on your SD card by means of File.list()
I just discovered that:
new File("/sdcard/").listFiles()
returns null if you do not have:
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
set in your AndroidManifest.xml file.
String[] listOfFiles = getActivity().getFilesDir().list();
or
String[] listOfFiles = Environment.getExternalStoragePublicDirectory (Environment.DIRECTORY_DOWNLOADS).list();
In addition to all the answers above:
If you are on Android 6.0+ (API Level 23+) you have to explicitly ask for permission to access external storage. Simply having
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
in your manifest won't be enough. You also have actively request the permission in your activity:
//check for permission
if(ContextCompat.checkSelfPermission(this,
Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_DENIED){
//ask for permission
requestPermissions(new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, READ_EXTERNAL_STORAGE_PERMISSION_CODE);
}
I recommend reading this: http://developer.android.com/training/permissions/requesting.html#perm-request
There are two things that could be happening:
READ_EXTERNAL_STORAGE
permission to your AndroidManifest.xml
Well, the AssetManager
lists files within the assets
folder that is inside of your APK file. So what you're trying to list in your example above is [apk]/assets/sdcard/Pictures.
If you put some pictures within the assets
folder inside of your application, and they were in the Pictures
directory, you would do mgr.list("/Pictures/")
.
On the other hand, if you have files on the sdcard that are outside of your APK file, in the Pictures
folder, then you would use File
as so:
File file = new File(Environment.getExternalStorageDirectory(), "Pictures");
File[] pictures = file.listFiles();
...
for (...)
{
log.e("FILE:", pictures[i].getAbsolutePath());
}
And relevant links from the docs:
File
Asset Manager
Try these
String appDirectoryName = getResources().getString(R.string.app_name);
File directory = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + getResources().getString(R.string.app_name));
directory.mkdirs();
File[] fList = directory.listFiles();
int a = 1;
for (int x = 0; x < fList.length; x++) {
//txt.setText("You Have Capture " + String.valueOf(a) + " Photos");
a++;
}
//get all the files from a directory
for (File file : fList) {
if (file.isFile()) {
list.add(new ModelClass(file.getName(), file.getAbsolutePath()));
}
}
My minSdkversion is 21, so I'm using ContextCompat.checkSelfPermission()
method to grant permissions apart from also adding the <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
in manifest. Thus, to get rid of the NullPointerException in spite of having files in your targeted directory, grant permissions as follows:-
public class MainActivity extends AppCompatActivity {
/*Other variables & constants here*/
private final int READ_EXTERNAL_STORAGE=100;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// ignore the button code
Button btn = (Button) findViewById(R.id.button);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
openWebView();
}
});
/*---------------------------- GRANT PERMISSIONS START-------------------------*/
// Main part to grant permission. Handle other cases of permission denied
// yourself.
if(ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED)
ActivityCompat.requestPermissions(this,new String[] {Manifest.permission.READ_EXTERNAL_STORAGE},READ_EXTERNAL_STORAGE);
/*---------------------------- GRANT PERMISSIONS OVER-------------------------*/
}
And the function that list all the files (in MainActivity.java), thanks to @Yury:-
public void getDownloadedFile() {
String path = Environment.getExternalStorageDirectory().toString()+"/Download/";
Log.d("Files", "Path: " + path);
File directory = new File(path);
File[] files = directory.listFiles();
if(directory.canRead() && files!=null) {
Log.d("Files", "Size: " + files.length);
for(File file: files)
Log.d("FILE",file.getName());
}
else
Log.d("Null?", "it is null");
}
If you are on Android 10/Q and you did all of the correct things to request access permissions to read external storage and it still doesn't work, it's worth reading this answer:
Android Q (10) ask permission to get access all storage. Scoped storage
I had working code, but me device took it upon itself to update when it was on a network connection (it was usually without a connection.) Once in Android 10, the file access no longer worked. The only easy way to fix it without rewriting the code was to add that extra attribute to the manifest as described. The file access now works as in Android 9 again. YMMV, it probably won't continue to work in future versions.
Try this:
public class GetAllFilesInDirectory {
public static void main(String[] args) throws IOException {
File dir = new File("dir");
System.out.println("Getting all files in " + dir.getCanonicalPath() + " including those in subdirectories");
List<File> files = (List<File>) FileUtils.listFiles(dir, TrueFileFilter.INSTANCE, TrueFileFilter.INSTANCE);
for (File file : files) {
System.out.println("file: " + file.getCanonicalPath());
}
}
}
Source: Stackoverflow.com