如何从应用程序打开 Pdf 到默认查看器？

Question

I'm trying to open pdf from my application to default document viewer in Nougat.

This is not duplicate cause I have different problem than others so read till end .

What I've tried:

I know i have to use FileProvider , Make provider.xml , get runtime permission about accessing that app .

in AndroidManifest.xml

 <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>

my GenericFileProvider

public class GenericFileProvider extends FileProvider {}

provider_path.xml

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
       <external-path name="external_files" path="."/>
</paths>

openign pdf by this

 val file = File(Environment.getExternalStorageDirectory().toString()+"pdfname")

            val intent = Intent()
            intent.action = Intent.ACTION_VIEW
            val uri = FileProvider.getUriForFile(context,  BuildConfig.APPLICATION_ID + ".provider", file)

           context.grantUriPermission("com.google.android.apps.docs", uri, Intent.FLAG_GRANT_WRITE_URI_PERMISSION or Intent.FLAG_GRANT_READ_URI_PERMISSION)


            intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)

            intent.setDataAndType(uri, "application/pdf")
            context.startActivity(intent)

My problem is :

at the time of viewing my pdf its first character has been changed . so it generates file not found exception

when i'm using this provider path . it delete my first character of pdf name

 my file name is  : /storage/emulated/0on the matter of.pdf
 my uri is : content://mypackage.provider/root/storage/emulated/0on%20the%20matter%20of.pdf
so pdf name is : n the matter of.pdf

when using provider_path this .

<root-path
           name="root"
           path="/" />

it adds 0 to my pdf name

 my file name is  : /storage/emulated/0on the matter of.pdf
 my uri is : content://mypackage.provider/root/storage/emulated/0on%20the%20matter%20of.pdf
so pdf name is : 0on the matter of.pdf

What should i do to get pdf name properly. what should i have to write in provider path .

Answer 1

Thanks to @VladyslavMatviienko and @greenapps . I've solved my issue.

As pointed out by @VladyslavMatviienko . I was passing wrong file path .

val file = File(Environment.getExternalStorageDirectory().toString()+"pdfname")

Instead of

val file = File(Environment.getExternalStorageDirectory().toString()+"/pdfname")

So its showing that java.io.FileNotFoundException:

So everything posted in my question is working fine for displaying pdf from my app to viewer in Oreo. So maybe it will help someone.