Convert file: Uri to File in Android

use

InputStream inputStream = getContentResolver().openInputStream(uri);    

directly and copy the file. Also see:

https://developer.android.com/guide/topics/providers/document-provider.html

Android + Kotlin

1. Add dependency for Kotlin Android extensions:

   implementation 'androidx.core:core-ktx:{latestVersion}'

2. Get file from uri:

   uri.toFile()

Android + Java

Just move to top ;)

What you want is...

new File(uri.getPath());

... and not...

new File(uri.toString());

Notes

1. For an android.net.Uri object which is named uri and created exactly as in the question, uri.toString() returns a String in the format "file:///mnt/sdcard/myPicture.jpg", whereas uri.getPath() returns a String in the format "/mnt/sdcard/myPicture.jpg".
2. I understand that there are nuances to file storage in Android. My intention in this answer is to answer exactly what the questioner asked and not to get into the nuances.

After searching for a long time this is what worked for me:

File file = new File(getPath(uri));


public String getPath(Uri uri) 
    {
        String[] projection = { MediaStore.Images.Media.DATA };
        Cursor cursor = getContentResolver().query(uri, projection, null, null, null);
        if (cursor == null) return null;
        int column_index =             cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        cursor.moveToFirst();
        String s=cursor.getString(column_index);
        cursor.close();
        return s;
    }