# JLine

© 2002, 2003, 2004, 2005 Marc Prud'hommeaux

# JLine Manual

JLine is a Java library for handling console input. It is similar in functionality to BSD editline and GNU readline. People familiar with the readline/editline capabilities for modern shells (such as bash and tcsh) will find most of the command editing features of JLine to be familiar.

JLine is distributed under the BSD license, meaning that you are completely free to redistribute, modify, or sell it with almost no restrictins. For more information on the BSD license, see http://www.opensource.org/licenses/bsd-license.php.

For information on obtaining the software under another license, contact the copyright holder: mwp1@cornell.edu.

JLine is hosted on SourceForge, and is located at http://jline.sf.net. The latest release can be downloaded from http://sourceforge.net/project/showfiles.php?group_id=64033. API documentation can be found in the javadoc directory.

JLine has no library dependencies, aside from a JVM of version 1.2 or higher. To install JLine, download the `jline.jar` file, and either place it in the system-wide java extensions directory, or manually add it to your `CLASSPATH`. The extensions directory is dependent on your operating system. Some few examples are:

- Macintosh OS X: `/Library/Java/Extensions` or `/System/Library/Java/Extensions`

- Microsoft Windows: `JAVAHOME\jre\lib\ext` (example: `C:\j2sdk1.4.1_03\jre\lib\ext`)

- UNIX Systems: `JAVAHOME/jre/lib/ext` (example: `/usr/local/java/jre/lib/ext`)

JLine is not 100% pure Java. On Windows, it relies on a `.dll` file to initialize the terminal to be able to accept unbuffered input. However, no installation is necessary for this: when initialized, JLine will dynamically extract the DLL to a temporary directory and load it. For more details, see the documentation for the `jline.WindowsTerminal` class.

On UNIX systems (including Macintosh OS X), JLine will execute the `stty` command to initialize the terminal to allow unbuffered input. For more details, see the documentation for the `jline.UnixTerminal` class.

For both Windows and UNIX systems, JLine will fail to initialize if it is run inside a strict security manager that does not allow the loading of libraries, writing to the file system, or executing external programs. However, for most console applications, this is usually not the case.

JLine should work on any Windows system, or any minimally compliant POSIX system (includling Linux and Macintosh OS X).

The platforms on which JLine has been confirmed to work are:

- Microsoft Windows XP

- RedHat Linux 9.0

- Debian Linux 3.0

- Macintosh OS X 10.3

Please report successes or failures to the author: mwp1@cornell.edu.

You can create your own keybindings by creating a `HOME/.jlinebindings.properties"` file. You can override the location of this file with the "`jline.keybindings`" system property.

The default keybindings are as follows:

    # Keybinding mapping for JLine. The format is:
    #    [key code]: [logical operation]

    # CTRL-B: move to the previous character
    2: PREV_CHAR

    # CTRL-G: move to the previous word
    7: PREV_WORD

    # CTRL-F: move to the next character
    6: NEXT_CHAR

    # CTRL-A: move to the beginning of the line
    1: MOVE_TO_BEG

    # CTRL-D: close out the input stream
    4: EXIT

    # CTRL-E: move the cursor to the end of the line
    5: MOVE_TO_END

    # CTRL-H: delete the previous character
    8: DELETE_PREV_CHAR

    # TAB, CTRL-I: signal that console completion should be attempted
    9: COMPLETE

    # CTRL-J, CTRL-M: newline
    10: NEWLINE

    # CTRL-K: erase the current line
    11: KILL_LINE

    # ENTER: newline
    13: NEWLINE

    # CTRL-L: clear screem
    12: CLEAR_SCREEN

    # CTRL-N: scroll to the next element in the history buffer
    14: NEXT_HISTORY

    # CTRL-P: scroll to the previous element in the history buffer
    16: PREV_HISTORY

    # CTRL-R: redraw the current line
    18: REDISPLAY

    # CTRL-U: delete all the characters before the cursor position
    21: KILL_LINE_PREV

    # CTRL-V: paste the contents of the clipboard (useful for Windows terminal)
    22: PASTE

    # CTRL-W: delete the word directly before the cursor
    23: DELETE_PREV_WORD

    # CTRL-?: delete the previous character
    127: DELETE_PREV_CHAR

This section discusses some common usages of the JLine API. For in-depth usage of the JLine API, see the javadoc.

A common task that console applications need to do is read in a password. While it is standard for software to not echo password strings as they are typed, the Java core APIs surprisingly do not provide any means to do this.

JLine can read a password with the following code:

    String password = new jline.ConsoleReader().readLine(new Character('*'));

This will replace every character types on the console with a star character.

Alternately, you can have it not echo password character at all:

    String password = new jline.ConsoleReader().readLine(new Character(0));

The `jline-demo.jar` file contains a sample application that reads the password. To run the sample, execute:

    java -cp jline-demo.jar jline.example.PasswordReader "*"

You can disable JLine by setting the System property "`jline.terminal`" to "`jline.UnsupportedTerminal`". For example:

    java -Djline.terminal=jline.UnsupportedTerminal jline.example.Example simple

You can create your own keybindings by creating a `HOME/.jlinebindings.properties"` file. You can override the location of this file with the "`jline.keybindings`" system property. To examine the format to use, see the `src/jline/keybindings.properties` file in the source distribution.

No, but you can use the `jline.ConsoleRunner` application to set up the system input stream and continue on the launch another program. For example, to use JLine as the input handler for the popular BeanShell console application, you can run:

    java jline.ConsoleRunner bsh.Interpreter

Yes. Try running:

    java jline.ConsoleRunner bsh.Interpreter

Yes. Try running:

    java jline.ConsoleRunner com.sun.tools.example.debug.tty.TTY args

No: JLine uses a couple small native methods in the Windows platform. On Unix, it is technically pure java, but relies on the execution of external (non-java) programs. See the installation section for more details.

See ???.

No: JLine has no ability to position the cursor on the console. It might someday evolve into a plausible Java curses implementation.

- Clearing the screen (CTRL-L) doesn't currently work on Windows.

- Add localization for all strings.

- Create a BNFCompletor that can handle any BNF.

- Add support for arrow keys on Windows.

- Fixed problem with the 0.9.0 distribution that failed to include the Windows jline.dll in the jline.jar, rendering it inoperable on Windows.

- Implemented proper interception or arrow keys on Windows, meaning that history can now be navigated with the UP and DOWN keys, and line editing can take place with the LEFT and RIGHT arrow keys.

- Changed license from GPL to BSD.

- Made "CTRL-L" map to clearing the screen.

- Fixed accidental dependency on JVM 1.4.

- Windows support using a native .dll

- A new ClassNameCompletor

- Many doc improvements

- Many bugfixes

- Better release system

- Automatically set terminal property by issuing stty on UNIX systems

- Additional tab-completion handlers

- Tested on Debian Linux and Mac OS 10.2

- Example includes dictionary, filename, and simple completion

- Initial release