Develop Reference

How to delete a file using the path

I'm building an app that allows the user to save the bitmap or share it without saving it. The 2nd functionality doesn't quite work. I understand that the app needs to save the file to the device before sharing it on a social media app so my idea was, immediately after the file was successfully shared, to automatically delete the file from the device. I've build a delete method trying 2 different approaches and neither have worked:
First approach:
public void deleteFile(String path){
File file = new File(path);
try {
file.getCanonicalFile().delete();
} catch (IOException e) {
e.printStackTrace();
}
}
Second approach:
public void deleteFile(String path){
File file = new File(path);
boolean deleted = file.delete();
}
And I'm calling deleteFile(String) from the sharing method:
public void shareMeme(Bitmap bitmap) {
String path = MediaStore.Images.Media.insertImage(Objects.requireNonNull(getContext()).getContentResolver(), bitmap, "Meme", null);
Uri uri = Uri.parse(path);
Intent share = new Intent(Intent.ACTION_SEND);
share.setType("image/*");
share.putExtra(Intent.EXTRA_STREAM, uri);
share.putExtra(Intent.EXTRA_TEXT, "This is my Meme");
getContext().startActivity(Intent.createChooser(share, "Share Your Meme!"));
deleteFile(path);
}

With respect to your stated problem, insertImage() returns a string representation of a Uri. That Uri is not a file. Calling getPath() on it is pointless, and you cannot delete anything based on that path.
More broadly, if your intention is to delete the content right away:
Do not put it in the MediaStore
Do not share it, as you will be deleting it before the other app has a chance to do anything with it
If you want to share it, but then delete it:
Do not put it in the MediaStore
Delete it the next day, or in a few hours, or something, as you have no good way of knowing when the other app is done with the content
To share an image with another app without using the MediaStore:
Save the image to a file in getCacheDir() (call that on a Context, such as an Activity or Service)
Use FileProvider to make that file available to other apps
Beyond that:
Do not use wildcard MIME types in ACTION_SEND. You are the one who is supplying the content to send. You know the actual MIME type. Use it.
Note that there is no requirement for an ACTION_SEND activity to honor both EXTRA_TEXT and EXTRA_STREAM. Most seem to do so, but that behavior is outside of the ACTION_SEND specification.
Note that insertImage() is deprecated on Android Q.

First, you need to check if your file exists, (maybe you set the wrong path?). Then delete the file
File file = new File(path);
if (file.exists()){
if (file.delete()) {
Toast.makeText(this, "file Deleted :" + path, Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "file not Deleted :" + path, Toast.LENGTH_SHORT).show();
}
}

Rescan older files with mediascannerconnection in local storage. files get not updated on windows

My android-application writes a bunch of csv-files and jpg-files to the internal storage of the device. I am using MediaScannerConnection.scanFile() to make the files accessable from my windows-system without rebooting the android-device.
private void scanFiles() {
File targetDirectory = new File(Environment.getExternalStorageDirectory(), "DIR_OF_MY_APP");
if (targetDirectory.exists()) {
List<File> filesToScan = getFiles(targetDirectory);
List<String> filePathsToScan = new ArrayList<>();
for(File file : filesToScan) {
filePathsToScan.add(file.getPath());
}
MediaScannerConnection.scanFile(this, filePathsToScan.toArray(new String[0]), null, new MediaScannerConnection.OnScanCompletedListener() {
#Override
public void onScanCompleted(String path, Uri uri) {
Log.d("OK", "Path: " + path);
Log.d("OK", "Uri : " + uri);
}
});
}
}
In my Logcat i can see every file is getting scanned. The new ones and the old ones.
My problem is when my app is adding new lines to an existing csv-file and the file is getting scanned, The new lines do not appear in the csv-file when its opend from my pc. How can i fix this problem?
I already tried to rename all the files from filename to tmp_filename, rescann all the files and rename them back from tmp_filename to filename and rescann them again. After this, i have can see the oldfilename-file and the tmp_oldfilename-file on my windows-computer. The tmp_oldfilename-file can not be opend (Unknown error on [memory-adress]). The oldfilename-file shows the not updated csv-file.
I also tried to use a intent to scan the files, since some questions on so say its going to update them:
for(File file : filesToScan) {
Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE)
Uri contentUri = Uri.fromFile(file);
mediaScanIntent.setData(contentUri);
sendBroadcast(mediaScanIntent);
Log.d("OK", "File: " + file.getName() + " scanned...");
}
here i can see the files getting scanned too, but they do not show up updated on my windows-computer.

Okay the only solution i came up with, is to set the usb-mode to load-only (this must be done by hand from the user) before performing the MediaScannerConnection.scanFile();. After this is done, the user can set the usb-mode back to mtp and than the csv-files will show up with the new added lines.
This is a really bad workarround, but still better than rebooting the device. If someone has an better solution, pls share.

Can't see my folder or files after creating in other applications

I have a small app that when I run it make a folder in my SD then save some Videos inside the folder
The thing is the app does the work and make the folder and save the files and I still can see it in SD using file manager or from my PC when I connect it via USB
But for e.g when I start Whatsup or my Gallery I can't see the folder or the videos !
I still can see the folder and videos that stored in the SD using File Manager
so what's wrong ? why I can't see the folder and videos in the Gallery or other programs when I want to attach the video ..
I used the same code link for my App to create the folder and check :
File folder = new File(Environment.getExternalStorageDirectory() + "/TollCulator");
boolean success = true;
if (!folder.exists()) {
success = folder.mkdir();
}
if (success) {
// Do something on success
} else {
// Do something else on failure
}

The Gallery works off of MediaStore, and WhatsApp may as well. Use MediaScannerConnection and its scanFile() static method to arrange to have your file(s) be indexed and available through the MediaStore, and see if that helps.

You need to Tell the media scanner about the new file so that it is immediately available to the user.
For example
MediaScannerConnection.scanFile(this,
new String[] { file.toString() }, null,
new MediaScannerConnection.OnScanCompletedListener() {
public void onScanCompleted(String path, Uri uri) {
Log.i("ExternalStorage", "Scanned " + path + ":");
Log.i("ExternalStorage", "-> uri=" + uri);
}
});

Deleted image still shows in android gallery untill I restart the emaulator

I'm deleting a file as such
File fileToDelete = new File("filepath");
Boolean fileDeleted = fileToDelete.delete();
The fileDeleted is true and when I check the DDMS the file is not there but if I click on the gallery it still shows the image that was just deleted. I have to restart the emulator to see the change.
Is there any way to see the changes without having to restart the emaulator? I'm using eclipse

The gallery is using Android's media database to display the list of media. Deleting the file will not be reflected in the database until it scans the filesystem again. That is for example done after rebooting.
You can either delete the file directly through the database or force it to scan the file or folder you just deleted.
File fileToDelete = new File("filepath");
boolean fileDeleted = fileToDelete.delete();
// request scan
Intent scanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
scanIntent.setData(Uri.fromFile(fileToDelete));
sendBroadcast(scanIntent);

It is to do with how Gallery shows the Image files. Image file's Thumbnails are cached in the MediaStore and all the details are present in the Mediastore contentProvider.
Deleting the file will not update this database. But when you restart the emulator, Mediascanning is done by android. If MediaScanning can be triggered , gallery will stop showing the files

I use the following code (which is also much like my code for creating a video which also tells the media system about file changes and correctly updates the Gallery):
private void deleteVideo(String videoUrl)
{
File videoFile = new File(videoUrl);
if (!videoFile.delete())
{
Log.e(TAG, "Failed to delete " + videoUrl);
}
else
{
MediaScannerConnection.scanFile(mContext,new String[] { videoUrl }, null, new MediaScannerConnection.OnScanCompletedListener()
{
public void onScanCompleted(String path, Uri uri)
{
Log.i("ExternalStorage", "Scanned " + path + ":");
Log.i("ExternalStorage", "-> uri=" + uri);
}
});
}
}

Trigger mediascanner on specific path (folder), how to?

I got this class:
import android.content.Context;
import android.media.MediaScannerConnection;
import android.net.Uri;
import android.util.Log;
public class MediaScannerWrapper implements
MediaScannerConnection.MediaScannerConnectionClient {
private MediaScannerConnection mConnection;
private String mPath;
private String mMimeType;
// filePath - where to scan;
// mime type of media to scan i.e. "image/jpeg".
// use "*/*" for any media
public MediaScannerWrapper(Context ctx, String filePath, String mime){
mPath = "/sdcard/DCIM/Camera";
mMimeType = "jpg";
mConnection = new MediaScannerConnection(ctx, this);
}
// do the scanning
public void scan() {
mConnection.connect();
}
// start the scan when scanner is ready
public void onMediaScannerConnected() {
mConnection.scanFile(mPath, mMimeType);
Log.w("MediaScannerWrapper", "media file scanned: " + mPath);
}
public void onScanCompleted(String path, Uri uri) {
// when scan is completes, update media file tags
}
}
How to use it in the other class?
I don't know how to properly use classes, I tried but nothing is working.
I do something wrong, but I don't know what, can someone help me with this.

The Story
Before Android 4.4, we could just send a broadcast to trigger the media scanner on any particular file, or folder or even on the root of the storage. But from 4.4 KitKat, this have been fixed by the Android Developers.
Why do I say fixed? The reason is simple. Sending a broadcast using MEDIA_MOUNTED on the root directory is very expensive. Running the Media Scanner is an expensive operation and the situation gets even worse when the user has got a lot of files in the storage and deep folder structures.
Before Android 4.4
Keep it straight and simple. If you are targeting your app before Android 4.4. But keep in mind not to use it on the root directory unless absolutely necessary.
sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://" + Environment.getExternalStorageDirectory())));
From Android 4.4
There are two ways for you.
i) The first one is very similar to the previous example, but may not work efficiently and is not recommended too.
sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + Environment.getExternalStorageDirectory())));
ii) Now, let us move on to the most recommended and efficient solution to this problem.
Add the file paths of the files which have been updated, like this, in a String type ArrayList
ArrayList<String> toBeScanned = new ArrayList<String>();
toBeScanned.add(item.getFilePath());
Now you need to run scanFile() static method of the MediaScannerConnection class and pass the String array containing the list of all the files which have been updated and needs to be media scanned.
You can also put a listener to respond when the scanning has been finished for individual files.
String[] toBeScannedStr = new String[toBeScanned.size()];
toBeScannedStr = toBeScanned.toArray(toBeScannedStr);
MediaScannerConnection.scanFile(getActivity(), toBeScannedStr, null, new OnScanCompletedListener() {
#Override
public void onScanCompleted(String path, Uri uri) {
System.out.println("SCAN COMPLETED: " + path);
}
});

Hey I found out how to do it with a very simple code.
Just call this line of code:
sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://" + Environment.getExternalStorageDirectory())));
This should trigger mediascanner.

In Android, there is a content database which is used by the media scanner to keep track of all the media content present on the device.
When Android boots up, the mediascanner service is launched and runs through the entire external storage to find if there is any new media content if it finds one then,
It adds an entry of that media content into the content database
Each entry in the content database contains metadata of the media content like Name, date, file size, type of file, etc..
So when you make a modification to a media content, you will need to update the content database also.
If the content database is not update then other applications also will not be able to access that particular media content.
Running the media scanner just updates the content database
Instead of running the media scanner, you can update the content database yourself and it should resolve the problem.
Here is an explanation on how to insert, delete, update using the content resolver. (Search for the section "Inserting, Updating, and Deleting Data")
Edit:
There is a sample code in this answer. Check for the answer by Janusz.

File file = new File(absolutePath);
Uri uri = Uri.fromFile(file);
Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, uri);
sendBroadcast(intent);

private void galleryAddPic() {
Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
File f = new File(mCurrentPhotoPath);
Uri contentUri = Uri.fromFile(f);
mediaScanIntent.setData(contentUri);
this.sendBroadcast(mediaScanIntent);
}
Reference: http://developer.android.com/training/camera/photobasics.html#TaskGallery
The Add the Photo to a Gallery Section

As #Aritra Roy's answer, i decide to make an experiment about this issue.
What i got here are:
Intent.ACTION_MEDIA_MOUNTED and Intent.ACTION_MEDIA_SCANNER_SCAN_FILE
can accept individual file path, so sendBroadcast(new
Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse(filePath)));
or sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED,
Uri.parse(filePath))); will be valid.
If you use individual file path with Intent.ACTION_MEDIA_MOUNTED on Kitkat or above, your application will still crash
If you use Intent.ACTION_MEDIA_SCANNER_SCAN_FILE or MediaScannerConnection on device lower than Kitkat, your application will not force close, but the method will just simply not working as you want.
From that experiment, i think the best method to handle is
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
MediaScannerConnection.scanFile(context, new String[]{imagePath}, null, new MediaScannerConnection.OnScanCompletedListener() {
public void onScanCompleted(String path, Uri uri) {
//something that you want to do
}
});
} else {
context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED,
Uri.parse("file://" + imagePath)));
}
Let me know if i missed something