Develop Reference

Share audio file from /data/user/0/ directory using FileProvider

I'm using FileProvider API for sharing content actually storing in internal storage.
Following is my xml configuration that linked with Provider configured in Manifiest file.
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<cache-path name="xs_audio" path="/audio/records"/>
</paths>
and code that I'm using to share is following:
private final static String FILE_PROVIDER = BuildConfig.APPLICATION_ID + ".fileprovider";
private String testPackageAppHaveAccess = "com.whats";
public static void shareDocument(Activity activity, CallRecordData data) {
Intent intent = new Intent();
intent.setAction(Intent.ACTION_SEND_MULTIPLE);
intent.putExtra(Intent.EXTRA_SUBJECT, "Record File");
intent.setType("audio/*");
ArrayList<Uri> files = new ArrayList<>();
//for (AudioModelObj image : data.getDocuments()) {
files.add(getImageUri(activity, data.getFile()));
//}
activity.grantUriPermission(testPackageAppHaveAccess, files.get(0), Intent.FLAG_GRANT_READ_URI_PERMISSION);
intent.putParcelableArrayListExtra(Intent.EXTRA_STREAM, files);
activity.startActivity(Intent.createChooser(intent, "Share Audio File."));
}
private static Uri getImageUri(Activity activity, String audioURI) {
if (Build.VERSION.SDK_INT < 24) {
return Uri.parse(audioURI);
} else {
URI uri = URI.create(audioURI);
File file = new File(uri);
return FileProvider.getUriForFile(activity, FILE_PROVIDER, file);
}
}
}
but while launching with app it's not attaching anything. In case of gmail it say "can't attach empty file". File is confirmedly available as I'm displaying list of file and playing.
For reference: Uri generating from getImageUri(..) is
/data/user/0/com.xl.cl.debug/cache/audio/records/17-10-17_170728_abc_.wav
Any suggestion what I'm doing wrong ?

<files-path> already points to what on some devices will be /data/user/0/com.xl.cl.debug
<cache-path> is what you should be using, replacing path with just the subdirectory of interest (audio/records), eliminating the /data/user/0/com.xl.cl.debug/cache bit
You are calling grantUriPermission(), where the first parameter is not a package
You are calling grantUriPermission(), where the first parameter is not a package identifying the app to which you are trying to grant permission
You are not adding FLAG_GRANT_READ_URI_PERMISSION to the Intent, which is the typical way of saying "the Uri in this Intent should be readable by the recipient of this Intent" (though it is possible that ACTION_SEND_MULTIPLE requires more work here, as I haven't played with that much)
No filesystem path in the human history has begun with content:/, so get rid of that
Calling new File() and supplying a value that is not a filesystem path is not going to work well
There may be more problems than those, but that should get you started

How to send(share) csv file?

How to send(share) *csv file?
I have android app, wich create a csv file. And i want to share it: send to email, open at excel and so on.
I read tutorials:set up file sharing and sharing a file, but can not understand: is it for my option or not?
I declare a manifest:
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="com.nam1.name2.fileprovider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/filepaths" />
</provider>
But what i should do next?
Can you tell me some simple code example (maybe git-repo) how to share file to another apps?
Thank you!
EDIT: I write some new code to share files (look at FileProvider example)
public class ExportActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_export);
Intent intentShareFile = new Intent(Intent.ACTION_SEND);
intentShareFile.setAction(Intent.ACTION_SEND);
File imagePath = new File(getApplicationContext().getFilesDir(), "statistics");
File newFile = new File(imagePath, "stat.csv");
CSVHelper csvHelper = new CSVHelper(SharedData.AllPlayersColl);
try {
String path=imagePath.getAbsolutePath();
csvHelper.SaveToCSV(path);
} catch (IOException e) {
e.printStackTrace();
}
Context context=getApplicationContext();
Uri contentUri = getUriForFile(context, "com.name1.name2.fileprovider", newFile);
List<ResolveInfo> resInfoList = getApplicationContext().getPackageManager()
.queryIntentActivities(intentShareFile, PackageManager.MATCH_DEFAULT_ONLY);
for (ResolveInfo resolveInfo : resInfoList) {
String packageName = resolveInfo.activityInfo.packageName;
getApplicationContext()
.grantUriPermission(packageName, contentUri, Intent.FLAG_GRANT_WRITE_URI_PERMISSION | Intent.FLAG_GRANT_READ_URI_PERMISSION);
}
intentShareFile.setData(contentUri);
intentShareFile.setFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
setResult(100, intentShareFile);
startActivityForResult(intentShareFile,100);
}
}
Where CSVHelper is:
fun SaveToCSV(fileName: String?) {
if (fileName == null)
throw NullPointerException("fileName is null!")
val writer = CSVWriter(FileWriter(fileName), '\t')
// make csv file
writer.writeNext(firstLine);
}
And filepaths is:
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<paths>
<files-path name="stat" path="statistics/" />
</paths>
But, i get a error:
Caused by: android.content.ActivityNotFoundException: No Activity found to handle Intent { act=android.intent.action.SEND dat=content://com.name1.name2.fileprovider/stat/stat.csv flg=0x2 }
I want, that when i start an Intent a list of variants shows (at android device) : email_app,excel_app and so on. So, i want to send noname intent.

FileProvider is a helper class designed to share files as content:// URIs instead of file:// URIs which have been deprecated for some time and forbidden since API level 24.
You have declared the content provider, you need now to configure it, i.e. choose what file it can serve. This is done in the xml/filepath file that you have declared in the meta-data. You will then be able to generate shareable content URIs using FileProvider.getUriForFile().
There is a complete wrap up
Unfortunately not all application understand content:// URIs. If you need to share a file with a (very old or badly written) application which only handle file:// URIs you may still use them if you set the target level of your application to 23 or lower.

How to open an APK file for all Android versions

Background
So far, there was an easy way to install an APK file, using this intent:
final Intent intent=new Intent(Intent.ACTION_VIEW)
.setDataAndType(Uri.fromFile(apkFile), "application/vnd.android.package-archive");
But, if your app targets Android API 24 and above (Nougat - 7.0) , and you run this code on it or newer, you will get an exception, as shown here , for example:
android.os.FileUriExposedException: file:///storage/emulated/0/sample.apk exposed beyond app through Intent.getData()
The problem
So I did what I was told: use the support library's FileProvider class, as such:
final Intent intent = new Intent(Intent.ACTION_VIEW)//
.setDataAndType(android.support.v4.content.FileProvider.getUriForFile(context,
context.getPackageName() + ".provider", apkFile),
"application/vnd.android.package-archive").addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
manifest:
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="${applicationId}.provider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/provider_paths"/>
</provider>
res/xml/provider_paths.xml :
<?xml version="1.0" encoding="utf-8"?>
<paths>
<!--<external-path name="external_files" path="."/>-->
<external-path
name="files_root"
path="Android/data/${applicationId}"/>
<external-path
name="external_storage_root"
path="."/>
</paths>
But, now it works only on Android Nougat. On Android 5.0, it throws an exception: ActivityNotFoundException.
What I've tried
I can just add a check for the version of Android OS, and use either methods, but as I've read, there should be a single method to use: FileProvider.
So, what I tried is to use my own ContentProvider that acts as FileProvider, but I got the same exception as of the support library's FileProvider.
Here's my code for it:
final Intent intent = new Intent(Intent.ACTION_VIEW)
.setDataAndType(OpenFileProvider.prepareSingleFileProviderFile(apkFilePath),
"application/vnd.android.package-archive")
.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
OpenFileProvider.java
public class OpenFileProvider extends ContentProvider {
private static final String FILE_PROVIDER_AUTHORITY = "open_file_provider";
private static final String[] DEFAULT_PROJECTION = new String[]{MediaColumns.DATA, MediaColumns.DISPLAY_NAME, MediaColumns.SIZE};
public static Uri prepareSingleFileProviderFile(String filePath) {
final String encodedFilePath = new String(Base64.encode(filePath.getBytes(), Base64.URL_SAFE));
final Uri uri = Uri.parse("content://" + FILE_PROVIDER_AUTHORITY + "/" + encodedFilePath);
return uri;
}
#Override
public boolean onCreate() {
return true;
}
#Override
public String getType(#NonNull Uri uri) {
String fileName = getFileName(uri);
if (fileName == null)
return null;
return MimeTypeMap.getSingleton().getMimeTypeFromExtension(fileName);
}
#Override
public ParcelFileDescriptor openFile(#NonNull Uri uri, #NonNull String mode) throws FileNotFoundException {
final String fileName = getFileName(uri);
if (fileName == null)
return null;
final File file = new File(fileName);
return ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY);
}
#Override
public Cursor query(#NonNull Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
final String filePath = getFileName(uri);
if (filePath == null)
return null;
final String[] columnNames = (projection == null) ? DEFAULT_PROJECTION : projection;
final MatrixCursor ret = new MatrixCursor(columnNames);
final Object[] values = new Object[columnNames.length];
for (int i = 0, count = columnNames.length; i < count; ++i) {
String column = columnNames[i];
switch (column) {
case MediaColumns.DATA:
values[i] = uri.toString();
break;
case MediaColumns.DISPLAY_NAME:
values[i] = extractFileName(uri);
break;
case MediaColumns.SIZE:
File file = new File(filePath);
values[i] = file.length();
break;
}
}
ret.addRow(values);
return ret;
}
private static String getFileName(Uri uri) {
String path = uri.getLastPathSegment();
return path != null ? new String(Base64.decode(path, Base64.URL_SAFE)) : null;
}
private static String extractFileName(Uri uri) {
String path = getFileName(uri);
return path;
}
#Override
public int update(#NonNull Uri uri, ContentValues values, String selection, String[] selectionArgs) {
return 0; // not supported
}
#Override
public int delete(#NonNull Uri uri, String arg1, String[] arg2) {
return 0; // not supported
}
#Override
public Uri insert(#NonNull Uri uri, ContentValues values) {
return null; // not supported
}
}
manifest
<provider
android:name=".utils.apps_utils.OpenFileProvider"
android:authorities="open_file_provider"
android:exported="true"
android:grantUriPermissions="true"
android:multiprocess="true"/>
The questions
Why does it occur?
Is there anything wrong with the custom provider I've created? Is the flag needed? Is the URI creation ok ? Should I add the current app's package name to it?
Should I just add a check if it's Android API 24 and above, and if so, use the provider, and if not, use a normal Uri.fromFile call ? If I use this, the support library actually loses its purpose, because it will be used for newer Android versions...
Will the support library FileProvider be enough for all use cases (given that I do have external storage permission, of course) ?

I can just add a check for the version of Android OS, and use either methods, but as I've read, there should be a single method to use: FileProvider.
Well, as the saying goes, "it takes two to tango".
To use any particular scheme (file, content, http, etc.), not only do you have to provide the data in that scheme, but the recipient needs to be able to support accepting the data in that scheme.
In the case of the package installer, support for content as a scheme was only added in Android 7.0 (and then, perhaps only because I pointed out the problem).
Why does it occur?
Because Google (see this and this).
Is there anything wrong with the custom provider I've created?
Probably not.
Should I just add a check if it's Android API 24 and above, and if so, use the provider, and if not, use a normal Uri.fromFile call ?
Yes. Or, if you prefer, catch the ActivityNotFoundException and react to that, or use PackageManager and resolveActivity() to see ahead of time if a given Intent (e.g., one with a content Uri) will work properly.
If I use this, the support library actually loses its purpose, because it will be used for newer Android versions
The "support library" has little to do with newer-vs.-older Android versions. Only a small percentage of the classes across the various Android Support artifacts are backports or compatibility shims. Vast quantities of it — FileProvider, ViewPager, ConstraintLayout, etc. — are simply classes that Google wanted to provide and support but wanted to make them available outside of the firmware.
Will the support library FileProvider be enough for all use cases
Only on Android 7.0+. Again, the stock Android package installer does not support content schemes prior to Android 7.0.

just for those who wonder how to finally install an APK properly, here:
#JvmStatic
fun prepareAppInstallationIntent(context: Context, file: File, requestResult: Boolean): Intent? {
var intent: Intent? = null
try {
intent = Intent(Intent.ACTION_INSTALL_PACKAGE)//
.setDataAndType(
if (VERSION.SDK_INT >= VERSION_CODES.N)
androidx.core.content.FileProvider.getUriForFile(context, context.packageName + ".provider", file)
else
Uri.fromFile(file),
"application/vnd.android.package-archive")
.putExtra(Intent.EXTRA_NOT_UNKNOWN_SOURCE, true)
.putExtra(Intent.EXTRA_RETURN_RESULT, requestResult)
.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
if (VERSION.SDK_INT < VERSION_CODES.JELLY_BEAN)
intent!!.putExtra(Intent.EXTRA_ALLOW_REPLACE, true)
} catch (e: Throwable) {
}
return intent
}
manifest
<provider
android:name="androidx.core.content.FileProvider" android:authorities="${applicationId}.provider" android:exported="false" android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS" android:resource="#xml/provider_paths"/>
</provider>
/res/xml/provider_paths.xml
<?xml version="1.0" encoding="utf-8"?>
<paths>
<!--<external-path name="external_files" path="."/>-->
<external-path
name="files_root" path="Android/data/${applicationId}"/>
<external-path
name="external_storage_root" path="."/>
</paths>

How to read files stored in cache from other applications? [duplicate]

I am trying to share image file in cache directory, i have the complete path, but not able to send the file in attachments, the code is
File shareImage=Utils.getBitmapFile();
Log.d("Activity", "get final path in result"+shareImage.getAbsolutePath());
/*MimeTypeMap mime = MimeTypeMap.getSingleton();
String ext=shareImage.getName().substring(shareImage.getName().lastIndexOf(".")+1);
String type = mime.getMimeTypeFromExtension(ext);
shareIntent.setType(type);
Intent shareIntent = new Intent(Intent.ACTION_SEND);
shareIntent.setType("image/*");
Uri shareImageUri = Uri.fromFile(shareImage);
Uri shareImageUri = Uri.fromParts("content", shareImage.getAbsolutePath(), null);//("content://"+shareImage.getAbsolutePath());
*/
Uri shareImageUri = Uri.fromFile(shareImage);
Log.d("Result ","uri is "+shareImageUri.toString());
shareIntent.putExtra(Intent.EXTRA_STREAM, shareImageUri);
startActivity(Intent.createChooser(shareIntent, "Share Results"));
the above commented code is not working
the send mail shows attachment,but not receiving end there is not attachment,
facebook sharing also shows no image in post
what the reason for this??
I have already seen the following SO Links how-to-use-share-image-using-sharing-intent-to-share-images-in-android and many others, none of them are able to resolve the issue
P.S.;
1.The aim is to take screenshot of screen save it in cache directory and share it online from there
2.Yes i do have file, I can pull it via DDMS from device and see on system.

I followed #CommonsWare's advice and used a FileProvider. Assuming your image is already in the internal cache directory as cache/images/image.png, then you can use the following steps. These are mostly a consolidation of the documentation.
Set up the FileProvider in the Manifest
<manifest>
...
<application>
...
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="com.example.myapp.fileprovider"
android:grantUriPermissions="true"
android:exported="false">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/filepaths" />
</provider>
...
</application>
</manifest>
Replace com.example.myapp with your app package name.
Create res/xml/filepaths.xml
<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<cache-path name="shared_images" path="images/"/>
</paths>
This tells the FileProvider where to get the files to share (using the cache directory in this case).
Share the image
File imagePath = new File(context.getCacheDir(), "images");
File newFile = new File(imagePath, "image.png");
Uri contentUri = FileProvider.getUriForFile(context, "com.example.app.fileprovider", newFile);
if (contentUri != null) {
Intent shareIntent = new Intent();
shareIntent.setAction(Intent.ACTION_SEND);
shareIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION); // temp permission for receiving app to read this file
shareIntent.setDataAndType(contentUri, getContentResolver().getType(contentUri));
shareIntent.putExtra(Intent.EXTRA_STREAM, contentUri);
startActivity(Intent.createChooser(shareIntent, "Choose an app"));
}
Documentation
FileProvider
Storage Options - Internal Storage
Sharing Files
Saving Files

what the reason for this?
As noted, other apps do not have access to your app's internal storage.
none of them are able to resolve the issue
Feel free to open a fresh StackOverflow question, where you explain, completely and precisely what specific solutions you have tried and what specific problems you have encountered.
but that does not seems to be working as per SO post!!!
Feel free to open a fresh StackOverflow question, where you explain, completely and precisely what "that does not seems to be working" means.
Or, use FileProvider, which offers this capability with no code required beyond an entry for it in your manifest.
Or, store your image on external storage, such as getExternalCacheDir().

I share cached image by followed steps .
1.Copy your cached image to target path.
public static File copyImage(String sourcePath, String targetPath){
try {
InputStream in = new FileInputStream(sourcePath);
OutputStream out = new FileOutputStream(targetPath);
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
in.close();
out.close();
return new File(targetPath);
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
2.Get the Uri of copy file.
Uri uri = Uri.fromFile(target);
3.Share image by intent
File dir = new File(Constant.INKPIC_PATH);//your custom path,such as /mnt/sdcard/Pictures
if(!dir.exists()){
dir.mkdirs();
}
File f = new File(dir,"temporary_file.jpg");
File target = copyImage(url,f.getAbsolutePath());
Uri uri = Uri.fromFile(target);
Intent intent = new Intent();
intent.setAction(Intent.ACTION_SEND);
intent.setType("image/*");
intent.putExtra(Intent.EXTRA_STREAM,uri );
context.startActivity(intent);

Create and Share a File from Internal Storage

My goal is to create a XML file on internal storage and then send it through the share Intent.
I'm able to create a XML file using this code
FileOutputStream outputStream = context.openFileOutput(fileName, Context.MODE_WORLD_READABLE);
PrintStream printStream = new PrintStream(outputStream);
String xml = this.writeXml(); // get XML here
printStream.println(xml);
printStream.close();
I'm stuck trying to retrieve a Uri to the output file in order to share it. I first tried to access the file by converting the file to a Uri
File outFile = context.getFileStreamPath(fileName);
return Uri.fromFile(outFile);
This returns file:///data/data/com.my.package/files/myfile.xml but I cannot appear to attach this to an email, upload, etc.
If I manually check the file length, it's proper and shows there is a reasonable file size.
Next I created a content provider and tried to reference the file and it isn't a valid handle to the file. The ContentProvider doesn't ever seem to be called a any point.
Uri uri = Uri.parse("content://" + CachedFileProvider.AUTHORITY + "/" + fileName);
return uri;
This returns content://com.my.package.provider/myfile.xml but I check the file and it's zero length.
How do I access files properly? Do I need to create the file with the content provider? If so, how?
Update
Here is the code I'm using to share. If I select Gmail, it does show as an attachment but when I send it gives an error Couldn't show attachment and the email that arrives has no attachment.
public void onClick(View view) {
Log.d(TAG, "onClick " + view.getId());
switch (view.getId()) {
case R.id.share_cancel:
setResult(RESULT_CANCELED, getIntent());
finish();
break;
case R.id.share_share:
MyXml xml = new MyXml();
Uri uri;
try {
uri = xml.writeXmlToFile(getApplicationContext(), "myfile.xml");
//uri is "file:///data/data/com.my.package/files/myfile.xml"
Log.d(TAG, "Share URI: " + uri.toString() + " path: " + uri.getPath());
File f = new File(uri.getPath());
Log.d(TAG, "File length: " + f.length());
// shows a valid file size
Intent shareIntent = new Intent();
shareIntent.setAction(Intent.ACTION_SEND);
shareIntent.putExtra(Intent.EXTRA_STREAM, uri);
shareIntent.setType("text/plain");
startActivity(Intent.createChooser(shareIntent, "Share"));
} catch (FileNotFoundException e) {
e.printStackTrace();
}
break;
}
}
I noticed that there is an Exception thrown here from inside createChooser(...), but I can't figure out why it's thrown.
E/ActivityThread(572): Activity
com.android.internal.app.ChooserActivity has leaked IntentReceiver
com.android.internal.app.ResolverActivity$1#4148d658 that was
originally registered here. Are you missing a call to
unregisterReceiver()?
I've researched this error and can't find anything obvious. Both of these links suggest that I need to unregister a receiver.
ChooserActivity has leaked IntentReceiver
Why does Intent.createChooser() need a BroadcastReceiver and how to implement?
I have a receiver setup, but it's for an AlarmManager that is set elsewhere and doesn't require the app to register / unregister.
Code for openFile(...)
In case it's needed, here is the content provider I've created.
public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException {
String fileLocation = getContext().getCacheDir() + "/" + uri.getLastPathSegment();
ParcelFileDescriptor pfd = ParcelFileDescriptor.open(new File(fileLocation), ParcelFileDescriptor.MODE_READ_ONLY);
return pfd;
}

It is possible to expose a file stored in your apps private directory via a ContentProvider. Here is some example code I made showing how to create a content provider that can do this.
Manifest
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.providertest"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="11" android:targetSdkVersion="15" />
<application android:label="#string/app_name"
android:icon="#drawable/ic_launcher"
android:theme="#style/AppTheme">
<activity
android:name=".MainActivity"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<provider
android:name="MyProvider"
android:authorities="com.example.prov"
android:exported="true"
/>
</application>
</manifest>
In your ContentProvider override openFile to return the ParcelFileDescriptor
#Override
public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException {
File cacheDir = getContext().getCacheDir();
File privateFile = new File(cacheDir, "file.xml");
return ParcelFileDescriptor.open(privateFile, ParcelFileDescriptor.MODE_READ_ONLY);
}
Make sure you have copied your xml file to the cache directory
private void copyFileToInternal() {
try {
InputStream is = getAssets().open("file.xml");
File cacheDir = getCacheDir();
File outFile = new File(cacheDir, "file.xml");
OutputStream os = new FileOutputStream(outFile.getAbsolutePath());
byte[] buff = new byte[1024];
int len;
while ((len = is.read(buff)) > 0) {
os.write(buff, 0, len);
}
os.flush();
os.close();
is.close();
} catch (IOException e) {
e.printStackTrace(); // TODO: should close streams properly here
}
}
Now any other apps should be able to get an InputStream for your private file by using the content uri (content://com.example.prov/myfile.xml)
For a simple test, call the content provider from a seperate app similar to the following
private class MyTask extends AsyncTask<String, Integer, String> {
#Override
protected String doInBackground(String... params) {
Uri uri = Uri.parse("content://com.example.prov/myfile.xml");
InputStream is = null;
StringBuilder result = new StringBuilder();
try {
is = getApplicationContext().getContentResolver().openInputStream(uri);
BufferedReader r = new BufferedReader(new InputStreamReader(is));
String line;
while ((line = r.readLine()) != null) {
result.append(line);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try { if (is != null) is.close(); } catch (IOException e) { }
}
return result.toString();
}
#Override
protected void onPostExecute(String result) {
Toast.makeText(CallerActivity.this, result, Toast.LENGTH_LONG).show();
super.onPostExecute(result);
}
}

So Rob's answer is correct I assume but I did it a bit differently. As far as I understand, with the setting in in provider:
android:exported="true"
you are giving public access to all your files?! Anyway, a way to give only access to some files is to define file path permissions in the following way:
<provider
android:authorities="com.your.app.package"
android:name="android.support.v4.content.FileProvider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/file_paths" />
</provider>
and then in your XML directory you define file_paths.xml file as follows:
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<files-path path="/" name="allfiles" />
<files-path path="tmp/" name="tmp" />
</paths>
now, the "allfiles" gives the same kind of public permission I guess as the option android:exported="true" but you don't really want that I guess so to define a subdirectory is the next line. Then all you have to do is store the files you want to share, there in that dir.
Next what you have to do is, as also Rob says, obtain a URI for this file. This is how I did it:
Uri contentUri = FileProvider.getUriForFile(context, "com.your.app.package", sharedFile);
Then, when I have this URI, I had to attach to it permissions for other app to use it. I was using or sending this file URI to camera app. Anyway this is the way how I got the other app package info and granted permissions to the URI:
PackageManager packageManager = getPackageManager();
List<ResolveInfo> list = packageManager.queryIntentActivities(cameraIntent, PackageManager.MATCH_DEFAULT_ONLY);
if (list.size() < 1) {
return;
}
String packageName = list.get(0).activityInfo.packageName;
grantUriPermission(packageName, sharedFileUri, Intent.FLAG_GRANT_WRITE_URI_PERMISSION | Intent.FLAG_GRANT_READ_URI_PERMISSION);
ClipData clipData = ClipData.newRawUri("CAMFILE", sharedFileUri);
cameraIntent.setClipData(clipData);
cameraIntent.setFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
cameraIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
startActivityForResult(cameraIntent, GET_FROM_CAMERA);
I left the code for camera as I did not want to take some other example I did not work on. But this way you see that you can attach permissions to URI itself.
The camera's thing is that I can set it via ClipData and then additionally set permissions. I guess in your case you only need FLAG_GRANT_READ_URI_PERMISSION as you are attaching a file to an email.
Here is the link to help on FileProvider as I based all of my post on the info I found there. Had some trouble finding a package info for camera app though.
Hope it helps.

None of the above answers helped. My problem was the point of passing intent extras but I'll walk you through all the steps to share a file.
Step 1: Create a Content Provider
This will make the file accessible to whichever app you want to share with.
Paste the following in the Manifest.xml file inside the <application></applicatio> tags
<provider
android:name="androidx.core.content.FileProvider"
android:authorities="{YOUR_PACKAGE_NAME}.fileprovider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/provider_paths" />
</provider>
Step 2: Define paths accessible by the content provider
Do this by creating a file called provider_paths.xml (or a name of your choice) under res/xml. Put the following code in the file
<?xml version="1.0" encoding="utf-8"?>
<paths>
<external-path
name="external"
path="." />
<external-files-path
name="external_files"
path="." />
<cache-path
name="cache"
path="." />
<external-cache-path
name="external_cache"
path="." />
<files-path
name="files"
path="." />
</paths>
Step 3: Create the Intent to share the file
Intent intentShareFile = new Intent(Intent.ACTION_SEND);
Uri uri = FileProvider.getUriForFile(getApplicationContext(), getPackageName() + ".fileprovider", fileToShare);
intentShareFile.setDataAndType(uri, URLConnection.guessContentTypeFromName(fileToShare.getName()));
//Allow sharing apps to read the file Uri
intentShareFile.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
//Pass the file Uri instead of the path
intentShareFile.putExtra(Intent.EXTRA_STREAM,
uri);
startActivity(Intent.createChooser(intentShareFile, "Share File"));

If you need to permission other apps to see your app's private files (for Share, or otherwise) you might be able to save some time and just use v4 compat library's FileProvider

This is what i'm using:
I combined some answers and used the current AndroidX Doku:
Sharing files Android Development
Basic Process: You change the manifest to make it possible for other apps to access your local files. the filepath's that are allowed to be accessed from outside are found in the res/xml/filepaths.xml. When sharing you create an intent to share and set a Flag that temporarily allowed the other app to access your local files. Android documentation claims this is the secure way to share files
Step1: Add FileProvider to Manifest
<provider
android:name="androidx.core.content.FileProvider"
android:authorities="com.YOUR.APP.PACKAGE.fileprovider"
android:grantUriPermissions="true"
android:exported="false">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/filepaths" />
</provider>
Step2: Add filepaths.xml to res/xml (if XML folder does not exists just create it yourself)
<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<files-path path="share/" name="share" />
</paths>
Step3: Use a function like this to start a file share. this function moves the file to the predefined share folder and creates a Url to it. the ShareDir is the File pointing to the files/share/ directory. the copy_File function copies the given file to the share directory in order to be accessible from the outside.
The function also makes it possible to Send the File as email with given header and body. if not needed just set it to empty strings
public void ShareFiles(Activity activity, List<File> files, String header, String body) {
ArrayList<Uri> uriList = new ArrayList<>();
if(files != null) {
for (File f : files) {
if (f.exists()) {
File file_in_share = copy_File(f, ShareDir);
if(file_in_share == null)
continue;
// Use the FileProvider to get a content URI
try {
Uri fileUri = FileProvider.getUriForFile(
activity,
"com.YOUR.APP.PACKAGE.fileprovider",
file_in_share);
uriList.add(fileUri);
} catch (IllegalArgumentException e) {
Log.e("File Selector",
"The selected file can't be shared: " + f.toString());
}
}
}
}
if(uriList.size() == 0)
{
Log.w("StorageModule", "ShareFiles: no files to share");
return;
}
Intent intent = new Intent(Intent.ACTION_SEND_MULTIPLE);
intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
intent.setType("text/html");
intent.putExtra(Intent.EXTRA_SUBJECT, header);
intent.putExtra(Intent.EXTRA_TEXT, body);
intent.putParcelableArrayListExtra(Intent.EXTRA_STREAM, uriList);
activity.startActivity(Intent.createChooser(intent, "Share Files"));
}