Develop Reference

Android Problem with sharing temporary file

I' m trying to create a temporary file and share it.
So I created this class:
public class GenerateFile {
public static File writeToFile(Context mcoContext, String sBody) {
String fileName = "LOG FILE_" + String.valueOf(System.currentTimeMillis()) +".txt";
File file = new File(mcoContext.getCacheDir(), fileName);
try{
FileWriter writer = new FileWriter(file);
writer.append(sBody);
writer.flush();
writer.close();
return file;
}catch (Exception e){
Toast.makeText(mcoContext, "File write failed: " + e.toString(), Toast.LENGTH_LONG).show();
}
return null;
}
}
to generate a file that after I will share here:
String logContent = "123";
File filePath = new File(file.getAbsolutePath(), "external_files");
filePath.mkdir();
Uri uri = FileProvider.getUriForFile(StatusActivity.this, getPackageName(), filePath);
Intent intent = ShareCompat.IntentBuilder.from(StatusActivity.this)
.setStream(uri) // uri from FileProvider
.setType("text/html")
.getIntent()
.setAction(Intent.ACTION_VIEW) //Change if needed
.setDataAndType(uri, "text/*")
.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
startActivity(intent);
And in the manifest there are already this permission:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="com.sec.android.provider.badge.permission.WRITE"/>
<uses-permission android:name="com.sec.android.provider.badge.permission.READ"/>
and the provider declaration
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="android.getqardio.com.gmslocationtest"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/provider_paths"/>
</provider>
The provider_paths class is defined in this way:
<?xml version="1.0" encoding="utf-8"?>
<paths>
<files-path
name="share"
path="external_files"/>
</paths>
But it generate the message, when I try to share it by mail or telegram "Unable to attach file" or "Unsupported attachment". Also it seems to me that the file is not created.

Other apps do not have access to your app's getCacheDir(). FLAG_GRANT_READ_URI_PERMISSION and FLAG_GRANT_WRITE_URI_PERMISSION are for content Uri values, not file Uri values. And, on Android 7.0+ devices, your code should crash with a FileUriExposedException.
Use FileProvider to make your content available to other apps, and use FileProvider.getUriForFile() to get the Uri to put in the Intent.

So I follow the suggestion of #CommonsWare, and I edited my code. This is the final result:
public class GenerateFile {
public static Uri getFileURI(Context context, String nameFile, String content, String fileExtension) {
DateFormat dateFormat = new SimpleDateFormat("yyyy_MM_dd");
Date date = new Date();
String fileName = dateFormat.format(date)+nameFile+fileExtension;
File file = new File(context.getCacheDir(), fileName);
try{
FileWriter writer = new FileWriter(file);
writer.append(content);
writer.flush();
writer.close();
//Toast.makeText(context, "Writing to the file completed successfully", Toast.LENGTH_LONG).show();
}catch (Exception e){
Toast.makeText(context, "File writing failed: " + e.toString(), Toast.LENGTH_LONG).show();
}
File filePath = new File(context.getCacheDir(), "");
File newFile = new File(filePath, fileName);
return FileProvider.getUriForFile(context, "MYPACKAGE.fileprovider", newFile);
}
}
and in another class:
private void sendFile(String nameFile, String logContent, String fileExtension) {
Uri contentUri = GenerateFile.getFileURI(getApplicationContext(), nameFile, logContent, fileExtension);
Intent intent = ShareCompat.IntentBuilder.from(StatusActivity.this)
.setStream(contentUri) // uri from FileProvider
.setType("text/plain")
.getIntent()
.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
startActivity(Intent.createChooser(intent, "send"));
}
so to send the file. I also deleted the permission (previously mentioned) in the manifest, because I didn't need it anymore.
And I also edited my provider and provider_path file like that:
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="MYPACKAGE.fileprovider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/provider_paths" />
</provider>
<?xml version="1.0" encoding="utf-8"?>
<cache-path
name="my_files"
path=""
/>
Now it works! Thank you very much guys for the help!

Did you specifically ask the user for those permissions? It's not enough to just put the permissions in the manifest for target sdks below 28. Also, in Android Q, you will need to work around external storage permissions altogether as this is disallowed.

Couldn't find meta-data for provider with authority

I have integrated Snapchat's Creative Kit in my Android app. After processing, I receive an image from the server in the form of Byte Array which I am saving to the disk and then sending the file to the Snapchat's Creative Kit as shown below.
private fun downloadImage(
fileName: String,
imageByteArray: ByteArray?): Uri? {
val state = Environment.getExternalStorageState()
if (Environment.MEDIA_MOUNTED == state) {
val downloadDir = File(
Environment.getExternalStorageDirectory(), context?.getString(R.string.app_name)
)
if (!downloadDir.isDirectory) {
downloadDir.mkdirs()
}
val file = File(downloadDir, fileName)
var ostream: FileOutputStream? = null
try {
ostream = FileOutputStream(file)
ostream.write(imageByteArray)
ostream.flush()
ostream.close()
}
} catch (e: IOException) {
e.printStackTrace()
}
val snapCreativeKitApi = SnapCreative.getApi(context!!)
val snapMediaFactory = SnapCreative.getMediaFactory(context!!)
lateinit var snapPhotoFile: SnapPhotoFile
try {
snapPhotoFile = snapMediaFactory.getSnapPhotoFromFile(file)
} catch (e: SnapMediaSizeException) {
return
}
val snapPhotoContent = SnapPhotoContent(snapPhotoFile)
snapCreativeKitApi.send(snapPhotoContent)
}
}
I have also added provider in the manifest file as shown below:
<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_app" />
</provider>
And in the provider_paths_app.xml, I have tried all the possible paths by referring this answer and none of them works.
<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<external-path
name="My App Name"
path="." />
</paths>
With the above path, I am getting the below error.
Couldn't find meta-data for provider with authority my.package.name.fileprovider
All I have to do is send this image to Snapchat but I am unable to figure out what I am doing wrong. Any help will be appreciated.

First, write the following tag in manifest under the <application> tag
<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>
Then create a xml folder in res and create a file named: provider_paths.xml
and then copy paste the code:
<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<external-path
name="external_files"
path="." />
</paths>
And now here's where most developers make mistakes: in your script, create your File with:
FileProvider.getUriForFile(Objects.requireNonNull(getApplicationContext()),
BuildConfig.APPLICATION_ID + ".provider", file);

<provider
android:name="androidx.core.content.FileProvider"
android:authorities="${applicationId}.fileprovider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/file_paths"></meta-data>
</provider>
This is my provider declaration, the value of ${applicationId} is "com.limxtop.research", make sure that the name of authorities is the same with that of the codes below.
// Create the file where the photo should save.
File file = null;
try {
file = createImageFile();
} catch (IOException e) {
break;
}
// The second parameter is the name of authorities.
Uri uri = FileProvider.getUriForFile(this,
"com.limxtop.research.fileprovider", file);
intent.putExtra(MediaStore.EXTRA_OUTPUT, uri);
intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION
| Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
startActivityForResult(intent, fullSizeRequestCode);
So, maybe your codes post here is not complete, there you should pass "my.package.name.fileprovider" as parameter some where.

In my case.
I have a library project .Let's call it :LibApk
When I code this : applicationId "my.package.name" in the build.grale(app)
when build gradle tell me that : Library projects cannot set applicationId.
applicationId is set to 'com.darcy.apkupdate' in default config.
So ,I delete applicationId "my.package.name" .
Then ,build.gradle look like this :
But I forgot update the AndroidManifest.xml file which use ${applicationId}
This is the problem!!!
So I changed the variable to constant .The result looks like below picture:
After This ,It's wokr for me!
Hope this is help you...

The problem here is, you use the class name .provider for authorities in manifest
and use .fileprovider class name in java code.
<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_app" />
</provider>
Couldn't find meta-data for provider with authority my.package.name.fileprovider
Just rename fileprovider to provider

If the build's suffix is different, it makes sense to make a change like this.
FileProvider.getUriForFile(mContext.get(), BuildConfig.APPLICATION_ID + ".fileprovider", file)

In My Case;
Manifest File:
<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>
Code:
import androidx.multidex.BuildConfig // NOT DO THIS!!!
val uri = FileProvider.getUriForFile(this,
BuildConfig.APPLICATION_ID+ ".provider", _tempFile)
Exception:
java.lang.IllegalArgumentException: Couldn't find meta-data for provider with authority androidx.multidex.provider
Do not use androidx.multidex.BuildConfig, Because this values are not the values of our application:
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
package androidx.multidex;
public final class BuildConfig {
public static final boolean DEBUG = false;
public static final String APPLICATION_ID = "androidx.multidex";
public static final String BUILD_TYPE = "release";
public static final String FLAVOR = "";
public static final int VERSION_CODE = -1;
public static final String VERSION_NAME = "";
public BuildConfig() {
}
}

{applicationId} == com.companyName.application
append ".provider"
which will be == com.example.test.provider
in xml authorities:com.example.test.provider
in activity Uri mPath = FileProvider.getUriForFile(this, "com.example.example.provider", imageFile);

FileProvider.getUriForFile(this, "{yourPAckageName}.fileprovider",
file);
to
FileProvider.getUriForFile(Objects.requireNonNull(getApplicationContext()),
BuildConfig.APPLICATION_ID + ".provider", file);
I spent a day finding a solution. This part is very important. That saved my day.

mImageFromCamera = FileProvider.getUriForFile(this, BuildConfig.APPLICATION_ID + ".fileprovider", mImageFile);
android:authorities="${applicationId}.fileprovider"
authorities must be same in xml and in code

First you use
File(getExternalFilesDir(null),context?.getString(R.string.app_name));
instead of
Environment.getExternalStorageDirectory(), context?.getString(R.string.app_name) // this is deprecated in API29
then use this
Uri contentUri = getUriForFile(getContext(), "com.mydomain.fileprovider", newFile);
For more help: File Provider Description

You can replace your BuildConfig import class file name:
import androidx.multidex.BuildConfig;
with:
import com.yourAppName.BuildConfig;

This is Because of this authority name difference
<provider
android:name="androidx.core.content.FileProvider"
android:authorities="${applicationId}.provider"
android:exported="false"
android:grantUriPermissions="true"
>
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/provider_paths"
/>
</provider>
here Look
<pre>android:authorities="${applicationId}.provider" </pre>
Here the authority name is you packagename.provider
(com.example.app.provider)
val uri: Uri? = FileProvider.getUriForFile(
this.contexts,
BuildConfig.APPLICATION_ID + ".provider",
file
)
whenever we copy paste the code the authority may be change from one source to another. in stackoverflow some devs put in manifest ${applicationId}.provider" and in uri they put (.fileprovider) FileProvider.getUriForFile(
this.contexts,
BuildConfig.APPLICATION_ID + ".fileprovider",
file
) this is the problem now authority is different that is showing in log

what solved my problem is :
replace your paths app file by this :
take a look at files root, i determined the path with my app package name, change the pkg name to yours.
<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<external-path
name="files_root"
path="Android/data/com.my.newproject4" />
<external-path
name="external_files"
path="." />
</paths>
and also in your provider
use your package name instead of ${applicationId}
same as me here
<provider
android:name="androidx.core.content.FileProvider"
android:authorities="com.my.newproject4.provider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/provider_paths" />
</provider>
this is what worked with me
the only solution and way after long time of trying and searching
just this was the problem
maybe it helps someone
i hope for you a good luck

Change the authorities to a unique name to solve the issue like
android:authorities="${applicationId}.myUniquefileprovider"
also in java code

I just removed the '$' from android:authorities="${applicationId}.provider" and it works like a charm now.

Its fileprovider and not provider
android:authorities="${applicationId}.fileprovider"

Failed to find configured root that contains

I'm sorry to ask an overly repeated question, but any of the answer here on stackoverflow really helped me.
I want to use a FileProvider to access file to a custom folder. My declaration in the manifest, inside the <application> tag:
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="my.package.name.provider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/provider_paths" />
</provider>
then, in provider_paths.xml
<paths>
<cache-path name="my_videos" path="MyFolderName/"/>
</paths>
(but I tried, instead of cache-path, files-path, external-path and external-files-path)
The creation of my files is:
public static Uri getUriFromFile(File file, Context context) {
int flags = Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION;
Uri uri = FileProvider.getUriForFile(context, context.getPackageName() + ".provider", file);
context.grantUriPermission(context.getPackageName(), uri, flags);
return uri;
}
public static File getMyDirectory() {
File root = new File(context.getCacheDir(), "MyFolderName");
if(root.mkdir()) Log.e(Consts.TAG, "Directory created");
return root;
}
...
File outputFile = new File(getMyDirectory(), filename + ".mp4");
videoUri = getUriFromFile(outputFile, this);
(and, instead of context.getCacheDir(), I tried context.getFilesDir(), Environment.getExternalStorageDirectory() and context.getExternalFilesDir(""))
and finally, I want to retrieve my file:
String pathToFile = "/my_videos/filename.mp4";
Uri file = getUriFromFile(new File(pathToFile), context);
tried with paths:
"/MyFolderName/filename.mp4"
"content://my.package.name.provider/my_videos/filename.mp4"
"content://my.package.name.provider/MyFolderName/filename.mp4"
ALL of this tries brought me to this error:
Failed to find configured root that contains /my_videos/filename.mp4
Any idea on what I am doing wrong? Thanks in advance!

I want to retrieve my file:
None of those are valid paths to the file.
You already have code that gives you a valid path to the file:
File outputFile = new File(getMyDirectory(), filename + ".mp4");
So, use the code that you already wrote.

FileProvider crash - npe attempting to invoke XmlResourceParser on a null String

This is a part of my manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.asd"
android:versionCode="118"
android:versionName="118" >
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="19" />
<application
android:name="com.example.asd.AsdApplication"
android:allowBackup="true"
android:allowTaskReparenting="true"
android:theme="#style/AsdTheme" >
...
<provider
android:name="com.example.asd.database.hq.ContentProviderDB"
android:authorities="ourContentProviderAuthorities" >
</provider>
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="com.example.asd.fileprovider"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/filepaths" />
</provider>
...
</application>
</manifest>
This is the filepaths file in raw/xml/filepaths.xml
<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<files-path name="media"/>
</paths>
I download a video from internet and save it to internal storage this way:
public static boolean saveInputStreamToInternalStorageFile(Context context, String filename, byte[] dataToWrite, Context ctx) {
FileOutputStream fos;
try {
fos = new FileOutputStream(context.getFilesDir() + File.separator + filename);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(dataToWrite);
oos.close();
return true;
} catch (FileNotFoundException e) {
e.printStackTrace();
return false;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
I try to use it like so:
private void playVideoFromDeviceWithWorkaround(String fileName) {
File newFile = new File(getFilesDir(), fileName);
Uri contentUri = FileProvider.getUriForFile(getApplicationContext(), "com.example.asd", newFile);
try {
vvVideoFullscreen.setVideoURI(contentUri);
showMediaControls = true;
playVideo();
} catch (Exception e) {
playVideoFromNetwork();
}
}
At this line:
Uri contentUri = FileProvider.getUriForFile(getApplicationContext(), "com.example.asd", newFile);
I get the following error:
java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.XmlResourceParser android.content.pm.ProviderInfo.loadXmlMetaData(android.content.pm.PackageManager, java.lang.String)' on a null object reference
at android.support.v4.content.FileProvider.parsePathStrategy(FileProvider.java:560)
at android.support.v4.content.FileProvider.getPathStrategy(FileProvider.java:534)
at android.support.v4.content.FileProvider.getUriForFile(FileProvider.java:376)

The problem was that in Manifest I had this line:
android:authorities="com.example.asd.fileprovider"
and when calling getUriForFile I was passing:
Uri contentUri = FileProvider.getUriForFile(getApplicationContext(), "com.example.asd", newFile);
So changed from "com.example.asd" to "com.example.asd.fileprovider" and it worked

You can do this without hardcoding the package name with an additional benefit of being able to run multiple variants on the same device (think release and debug with applicationIdSuffix, see these issues):
Based on FileProvider.java:560
final ProviderInfo info = context.getPackageManager()
.resolveContentProvider(authority, PackageManager.GET_META_DATA);
final XmlResourceParser in = info.loadXmlMetaData( //560
context.getPackageManager(), META_DATA_FILE_PROVIDER_PATHS);
you were using the wrong authority and it didn't find the ContentProvider (info == null).
Change your manifest to (${applicationId} will be replaced by Manifest Merger)
android:authorities="${applicationId}.share"
and
Uri uri = FileProvider.getUriForFile(context, context.getPackageName() + ".share", result);
The .share suffix is optional, in case you have a real ContentProvider which is better to have the package name as the authority.

In my case, I got the error because the
BuildConfig.APPLICATION_ID
was being imported from
import android.support.v4.BuildConfig;
So the string it returned was "android.support.v4" instead of my project package name. Check out the import file is from your import project.Buildconfig and not another. Example:
import com.example.yourProjectName.BuildConfig;
Finally, in <provider> tag in Manifest I have android:authorities="${applicationId}" to always get my project package name as the authority
<manifest>
..
..
<application>
..
..
<provider
android:name="android.support.v4.content.FileProvider"
android:authorities="${applicationId}"
android:exported="false"
android:grantUriPermissions="true">
<meta-data
android:name="android.support.FILE_PROVIDER_PATHS"
android:resource="#xml/ruta_fileprovider" />
</provider>
</application>
</manifest>

First, be sure that you provider android:authorities does not conflict with your other providers. Besides that you may choose any name for the last part of its name: "provider", "fileprovider" etc., but app crashes when there are more than one android:authorities listed, while documentation states that it allows multiple values listed.
file:// scheme is now not allowed to be attached with Intent on targetSdkVersion >= 24 (Android N 7.0), only content:// is always passed for all devices (Android 5, 6 and 7). But we encountered that Xiaomi breaks this Google convention and sends file://, hence data.getData().getAuthority() gives empty string.
final String uriScheme = currentUri.getScheme();
if ("content".equals(uriScheme)) {
// getting full file path (works with some providers, i.e. Gallery)
path = FileUtils.getPath(getContext(), currentUri);
if (path != null) {
currentFile = new File(path);
}
} else if ("file".equals(uriScheme)) {
// in a rare case we received file:// in currentUri, we need to:
// 1. create new File variable from currentUri that looks like "file:///storage/emulated/0/download/50044382b.jpg"
// 2. generate a proper content:// Uri for it
currentFile = new File(currentUri.getPath());
String authority = data.getData().getAuthority();
if (authority != null && !authority.isEmpty()) {
currentUri = FileProvider.getUriForFile(getActivity(), authority, currentFile);
}
} else {
// throw exception
}
Also, the bug when FileProvider.getUriForFile() resulted in crash java.lang.IllegalArgumentException: Failed to find configured root that contains /storage/emulated/0/Android/data/com.example/files/attachments/image.jpg was fixed in Android Support Library v24.2.0. The problem was that FileProvider.java did not see external-path folders.

If you're building your AUTHORITY at runtime using BuildConfig make sure you use the full class name including your package name.
Bad:
final String AUTHORITY = BuildConfig.APPLICATION_ID + ".provider";
Good:
final String AUTHORITY = com.mycompany.myapp.BuildConfig.APPLICATION_ID + ".provider";

Following worked for me.
mUri = FileProvider.getUriForFile(this,
BuildConfig.APPLICATION_ID + ".provider",
fileObject);

Here is what i did to fix the issue. I gave fully qualified name in android:name. It works in android 6,7,8
<provider android:authorities="${applicationId}.opener.provider"
android:exported="false" android:grantUriPermissions="true"
android:name="io.github.pwlin.cordova.plugins.fileopener2.FileProvider">
<meta-data android:name="android.support.FILE_PROVIDER_PATHS" android:resource="#xml/provider_paths" />
</provider>

You should try it:
Context context = PostAdapter.this.activity;
StringBuilder stringBuilder2 = new StringBuilder();
stringBuilder2.append(PostAdapter.this.activity.getPackageName());
stringBuilder2.append(".provider");
Uri uri;
uri = FileProvider.getUriForFile(context,stringBuilder2.toString(), newFile);

This is what you need to do:
Uri fileURI = FileProvider.getUriForFile(getActivity(), getActivity().getPackageName() + ".fileprovider", file);

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"));
}