You can use this lightweight library to implement the attachment feature (taking pictures using the camera, picking up files/images from the gallery or file system, or google drive). The library helps you to simplify all the processes related to picking files without worrying about system permissions.
SimpleStorage simplifies Android Storage Access Framework (SAF) for file management across API levels.
This library reads word documents (.doc and .docx), txt and PDF files, and gives the output content of the document as a String.
An RxJava2 implementation of the Android AssetManager.
It is a library for Android that lets you to explore your device file system. It gives you an easy access to files and directories. You can get direct intent for file to run it on your device that matches with file type.
Using this library, you can easily extract jar file using android app.
Rx methods to get a File and Image or Video thumbnails from any
DocumentProvider on Android (Drive, Dropbox, Photos etc)
Reactive wrapper around Android's FileObserver.
Amaze File Manager source code.
Goreinu allows to copy application files on sdcard.
A helper class to write files in external android storage.
Localify is a small library which allows to load a content from files which are stored under assets and/or raw directory. It can be useful when you have to load some init data or during tests to load mock data.
A tiny library that assists in saving and restoring objects to and from disk using RxJava on Android.
Library to create, read, delete, append, encrypt files and more, on internal or external disk spaces with a really simple API.