JStudio is an integrated development environment(IDE) for developing Android apps or Java/Kotlin console programs on your device with support for auto completion and real time error checking among others.
It supports modern Java build tools like Gradle Ant and Maven.

Features

Editor
- Code completion for java.
- Real Time error checking.
- Auto backup if you leave the app without saving.
- Undo and Redo.
- Support for characters not normally present in the virtual keyboard like tabs and arrows.

Terminal
- Access the shell and commands that ship with android.
- Preinstalled with basic unix command like grep and find(Missing in older android versions but newer devices already ship with them)
- Support for tab and arrows even if the virtual keyboard lacks them.

File Manager
- Access your files without leaving the app.
- Copy Paste and Delete.