Develop Reference

Java listFiles return null but I can still find files when I have a full path to a file in the directory

So in my react-native module I Want to find the already created files that my app has created in
/storage/emulated/0/Download/xx/xx
It work great when My app create those files in those directory and File.listFiles("/storage/emulated/0/Download/xx/xx") return all those files without any problem.
Now when I uninstall my app and install it again, listFiles cant find those old files anymore!!
But only find the files that I create a new.
Now for those of you who think this is about permission I already check it and have full access
status{"android.permission.WRITE_EXTERNAL_STORAGE":"granted","android.permission.READ_EXTERNAL_STORAGE":"granted"}
Here is the Java method that I have
#ReactMethod(isBlockingSynchronousMethod = true)
public String getAllAppDownloadedFiles(String folderPath) {
File folder = new File(folderPath);
String result = "";
if (!folder.exists())
return result;
File[] files = folder.listFiles();
for (int i = 0; i < files.length; i++) {
File file = files[i];
if (file.isFile())
result += file.getAbsolutePath() + (files.length - 1 > i ? "," : "");
}
return result;
}
I should point out that the problem only exist when I run the app on my mobile and not in emulator. I suspect it has to do with the version of API.
Any Idea how I could fix this?

Android: How to list all the files in a directory in to an array?

I have a variable "directorypath". It has the path to a directory in sd card.
Ex: "sdcard/images/scenes"
Now, I want to list all the files in the "directorypath" and want an Array to store all the file names in it.
Ex: Array[0]= Filename1, Array[1]= Filename2 Etc...
I tried something like Array[] myArray = directorypath.listfile(); but didn't work..!
Can anyone give me the code or at least help me? Much appreciated.

I think the problem you are facing is related to the external storage directory file path. Don't use whole path as variable if you can access with environment.
String path = Environment.getExternalStorageDirectory().toString()+"/images/scenes";
Also, you can use the API listfiles() with file object and it will work. For eg ::
File f = new File(path);
File file[] = f.listFiles();

Try the following code which may help you
List<File> getListFiles(File parentDir) {
ArrayList<File> inFiles = new ArrayList<File>();
File[] files = parentDir.listFiles();
for (File file : files) {
if (file.isDirectory()) {
inFiles.addAll(getListFiles(file));
} else {
inFiles.add(file);
}
}
return inFiles;
}
This will return you list of files under the directory you specified.
From the File object in list.. you will get all information about files you required.

Try the following code:
File externalStorageDirectory = Environment.getExternalStorageDirectory();
File folder = new File(externalStorageDirectory.getAbsolutePath() + "/FilePath");
File file[] = folder.listFiles();
if (file.length != 0) {
for (int i = 0; i < file.length; i++) {
//here populate your list
}
} else {
//no file available
}

According to your error message "Cannot resolve listFiles()", you are trying to call a method on a String object, when you actually want to be calling that on a File object.
Create a new File object,
String parentDirectory = "path/to/files";
File dirFileObj = new File(parentDirectory);
File[] files = dirFileObj.listFiles();

I was indeed calling a function for improper data type. i.e., listfiles() won't work on String type variable..!!
SO, I created a File type variable and a File[] array to pass the list of files..!
This solved the issue.

its very simple Just two lines of code
File mListofFiles = new File(Environment.getExternalStorageDirectory.getAbsolutePath()+"/",childpath:Foldername);
File f = new File(mListofFiles.toString());
File file[] = f.listFiles();

Delete files from a known folder

I'm trying to delete all files that are exists in a known path.
I've used the next function to do so -
public void deleteAllImages(){
Log.d(TAG, "ENTERD DELETED ALL IMAGES ");
String path = "/data/data/yourapp/app_data/imageDir/";
File directory = new File(path);
if (directory.isDirectory()){
Log.d(TAG, "ENTERED IF ");
for (File child : directory.listFiles()){
Log.d(TAG, "ENTERED FOR "+ child);
child.delete();
}
}
}
But it seem that it never getting into the if statement - guess it mean that it doesn't treat directory as one. So what am I doing wrong here?

Most likely the path is not correct. The isDirectory() will return false in the following cases:
The path points to file (obviously), and not to directory.
The path
is invalid (i.e. there is no such file/directory exists).
There is
not enough permissions granted to your application to determine
whether path points to directory.

Try this :
if (dir.isDirectory()) {
String[] children = dir.list();
for (int i = 0; i < children.length; i++) {
new File(dir, children[i]).delete();
}
}
Check this : Delete files from folder
Hope this helps.

try this...
String path = "/data/data/yourapp/app_data/imageDir/";
File file = new File(path);
if(file.isDirectory()) {
File[] files = file.listFiles();
if(files != null && files.length > 0) {
for (File file2 : files) {
file2.delete();
}
}
}

Android How can I read filenames from a specific folder?

I would like to scan a specific folders for all filenames inside to save them to an array.
But how can I access the sd Card to do this?
Help would be great (io / enviroment???)

Environment.getExternalStorageDirectory() will link you to the SD card if one is inserted in the phone. Otherwise it just links you to your phone storage. Here's a link to more information on Environment http://developer.android.com/reference/android/os/Environment.html.
File file = new File(Environment.getExternalStorageDirectory()+"/folder/");
File[] files = file.listFiles();
String[] fileNames = new String[files.length];
for(int i = 0; i < files.length; i++)
fileNames[i] = files[i].getName();

You can use the following code:
String filesDirectory = Environment.getExternalStorageDirectory().getAbsolutePath()+"/YOUR_SPECIFIC_FOLDER/"
File fileList = new FilefilesDirectory
if (fileList != null)
{
File[] filenames = fileList.listFiles();
//Loop through each file and get the file name
String fileNamesArray[] = new String[filenames.length];
int i=0;
for (File tempFile : filenames)
{
fileNamesArray[i] = tempFile.getName();
i++;
}
}

How to get count of images stored in SD card

I need to calculate the number of images stored in SD card and so i would like to name the images unique like Sample0,Sample1,Sample2,Sample3,etc.
Is it Possible?

It gives the number of images present in the images folder of your SD card:
File dir = new File(Environment.getExternalStorageDirectory()
+ "/images");
File[] files = dir.listFiles();
int numberOfImages=files.length;

I now it's been a long time, but, the method above would give you the number of any kind of files and directories within images folder, not only the images number, and doesn't look for images in subfolders inside the images directory.
Let's say we have this structure:
Images/
- img1.jpg
- img2.jpg
- data.dat
- whatever.pdf
- Folder/
- img3.png
The method above will give you 5 and you should obtain 3 isn't it?
I've been working on something similar and I'm pretty sure there is a more efficient way, but with this method I get the number of all images within the SDCard, or any given directory and its subfolders...
Here we go:
public int countImgs(File file, int number) {
File[] dirs = file.listFiles();
String name = "";
if (dirs != null) { // Sanity check
for (File dir : dirs) {
if (dir.isFile()) { // Check file or directory
name = dir.getName().toLowerCase();
// Add or delete extensions as needed
if (name.endsWith(".png") || name.endsWith(".jpg")
|| name.endsWith(".jpeg")) {
number++;
}
} else number = countImgs(dir, number);
}
}
return number;
}
Where the param file is the root directory and the number would be 0 at start. So to use it:
int imgNumber = countImgs(Environment.getExternalStorageDirectory(), 0);

it will be an error when files = null when get the count of images stored in SD card
File dir = new File(Environment.getExternalStorageDirectory() + "/images");
File[] files = dir.listFiles();
String strnumberOfImages=files.length;
int intnumberOfImages= 0;
try{
intnumberOfImages = Integer.parseInt( strnumberOfImages);
}catch ( Exception e ){
intnumberOfImages = 0;
}
if just check empty or not
File dir = new File(Environment.getExternalStorageDirectory()+ "/images");
File[] files = dir.listFiles();
if(files != null){
// there are picz
}else{
// sd card empty
}