Jexer - Java Text User Interface library

This library implements a text-based windowing system loosely reminiscent of Borland's Turbo Vision system. It looks like this:

Jexer works on both Xterm-like terminals and Swing, and supports images in both Xterm and Swing. On Swing, images are true color:

On Xterm, images are dithered to a common palette:

License

Jexer is available to all under the MIT License. See the file LICENSE for the full license text.

Obtaining Jexer

Jexer is available on Maven Central:

<dependency>
  <groupId>com.gitlab.klamonte</groupId>
  <artifactId>jexer</artifactId>
  <version>0.3.2</version>
</dependency>

Binary releases are available on SourceForge: https://sourceforge.net/projects/jexer/files/jexer/

The Jexer source code is hosted at: https://gitlab.com/klamonte/jexer

1.0.0 Release

Jexer's original list of features for its 1.0.0 release are undergoing final testing. Issues and merge requests are disabled until that release is out.

Documentation

• Java API Docs

• Wiki

• Jexer web page

• Development Standards

Programming Examples

The examples/ folder currently contains:

• A prototype tiling window manager in less than 250 lines of code.

• A much slicker prototype tiling window manager in less than 200 lines of code.

• A prototype image thumbnail viewer in less than 350 lines of code.

jexer.demos contains official demos showing all of the existing UI controls. The demos can be run as follows:

• 'java -jar jexer.jar' . This will use System.in/out with Xterm-like sequences on non-Windows non-Mac platforms. On Windows and Mac it will use a Swing JFrame.

• 'java -Djexer.Swing=true -jar jexer.jar' . This will always use Swing on any platform.

• 'java -cp jexer.jar jexer.demos.Demo2 PORT' (where PORT is a number to run the TCP daemon on). This will use the Xterm backend on a telnet server that will update with screen size changes.

• 'java -cp jexer.jar jexer.demos.Demo3' . This will use System.in/out with Xterm-like sequences. One can see in the code how to pass a different InputReader and OutputReader to TApplication, permitting a different encoding than UTF-8.

• 'java -cp jexer.jar jexer.demos.Demo4' . This demonstrates hidden windows and a custom TDesktop.

• 'java -cp jexer.jar jexer.demos.Demo5' . This demonstrates two demo applications using different fonts in the same Swing frame.

• 'java -cp jexer.jar jexer.demos.Demo6' . This demonstrates two applications performing I/O across three screens: an Xterm screen and Swing screen, monitored from a third Swing screen.

• 'java -cp jexer.jar jexer.demos.Demo7' . This demonstrates the BoxLayoutManager, achieving a similar result as the javax.swing.BoxLayout apidocs example.

More Screenshots

Jexer can be run inside its own terminal window, with support for all of its features including images and mouse, and more terminals:

Sixel output uses a single palette which works OK for a variety of real-world images:

The color wheel with that palette is shown below:

Terminal Support

The table below lists terminals tested against Jexer's Xterm backend:

Terminal	Environment	Mouse Click	Mouse Cursor	Images
xterm	X11	yes	yes	yes
jexer	CLI, X11, Windows	yes	yes	yes
mlterm	X11	yes	yes	yes
RLogin	Windows	yes	yes	yes
alacritty(3)	X11	yes	yes	no
gnome-terminal	X11	yes	yes	no
iTerm2	Mac	yes	yes	no(5)
kitty(3)	X11	yes	yes	no
lcxterm(3)	CLI, Linux console	yes	yes	no
mintty	Windows	yes	yes	no(5)
rxvt-unicode	X11	yes	yes	no(2)
xfce4-terminal	X11	yes	yes	no
aminal(3)	X11	yes	no	no
konsole	X11	yes	no	no
yakuake	X11	yes	no	no
Windows Terminal(6)	Windows	no	no	no(2)
screen	CLI	yes(1)	yes(1)	no(2)
tmux	CLI	yes(1)	yes(1)	no
putty	X11, Windows	yes	no	no(2)
Linux	Linux console	no	no	no(2)
qodem(3)	CLI, Linux console	yes	yes(4)	no
qodem-x11(3)	X11	yes	no	no
yaft	Linux console (FB)	no	no	yes

1 - Requires mouse support from host terminal.

2 - Also fails to filter out sixel data, leaving garbage on screen.

3 - Latest in repository.

4 - Requires TERM=xterm-1003 before starting.

5 - Sixel images can crash terminal.

6 - Version 0.7.3291.0, on Windows 10.0.18362.30. Tested against WSL-1 Debian instance.

See Also

• Tranquil Java IDE is a TUI-based integrated development environment for the Java language that was built using a very lightly modified GPL version of Jexer. TJ provided a real-world use case to shake out numerous bugs and limitations of Jexer.

• LCXterm is a curses-based terminal emulator that allows one to use Jexer with full support on the raw Linux console.

• ptypipe is a small C utility that permits a Jexer TTerminalWindow to resize the running shell when its window is resized.

Acknowledgements

Jexer makes use of the Terminus TrueType font made available here .