Does javax.swing need X11 on Unix?

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sakcee@gmail.com - 03 May 2007 23:21 GMT

Hi

this question might as well be that "does OS needs processor to run "
but anyway

Does javax.swing needs X11 on the unix platform? I have a machine
which havs just barebone Unix with no windowing system and although
the calls to javax.swing.UIMangere is in catch all block, it still
crashes that it "Can't connect to X11 window server using".

what I am wondering is that how can it trick the catch all , and does
swing needs windowing system to run.

thanks

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Tom Hawtin - 03 May 2007 23:48 GMT

> Does javax.swing needs X11 on the unix platform? I have a machine
> which havs just barebone Unix with no windowing system and although
> the calls to javax.swing.UIMangere is in catch all block, it still
> crashes that it "Can't connect to X11 window server using".

Are you expecting it to do some ASCII art? ;)

Sun's AWT X implementation requires X "client" libraries: xlib. I'm not
entirely sure of the exact details. You will also need to have the
DISPLAY environment variable pointing to a working X Server. The X
Server need not be on the same machine, but you need to be able to
connect to it. For instance, I sometimes run Java programs on my Ubuntu
machine, but displaying on my Vista laptop.

You don't technically need a desktop environment (e.g. KDE, GNOME, RoX)
or even a window manager (e.g. metacity, sawfish, fvwm, twm) (although
you wont get window frames, unless you explicitly get Swing (the PL&F)
to draw them).

Older versions also required the Motif library. I think for 1.5 this is
the default on Solaris but not on Linux (google for AWT_TOOLKIT).

Tom Hawtin

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Matt Humphrey - 04 May 2007 01:57 GMT

| > Does javax.swing needs X11 on the unix platform? I have a machine
| > which havs just barebone Unix with no windowing system and although
[quoted text clipped - 17 lines]
| Older versions also required the Motif library. I think for 1.5 this is
| the default on Solaris but not on Linux (google for AWT_TOOLKIT).

Also, if you just want to run Java without a display at all and are trying
to get around any GUI or Font requirements, look into Xvfb--X virtual frame
buffer. It gives you an X Server that you can direct Java to, but does not
actually display anything. I've used this when I've had servlets doing
headless rendering, but that was quite a number of years ago--there may be
better techniques available now.

Cheers,
Matt Humphrey matth@ivizNOSPAM.com http://www.iviz.com/

Reply to this Message

Daniel Pitts - 04 May 2007 02:11 GMT

> | > Does javax.swing needs X11 on the unix platform? I have a machine
> | > which havs just barebone Unix with no windowing system and although
[quoted text clipped - 27 lines]
> Cheers,
> Matt Humphrey m...@ivizNOSPAM.comhttp://www.iviz.com/

You can start Java in headless mode too. There are a lot of operations
you CAN do in headless mode.

Reply to this Message

Tom Hawtin - 04 May 2007 03:40 GMT

>> Also, if you just want to run Java without a display at all and are trying
>> to get around any GUI or Font requirements, look into Xvfb--X virtual frame
>> buffer. It gives you an X Server that you can direct Java to, but does not
>> actually display anything. I've used this when I've had servlets doing
>> headless rendering, but that was quite a number of years ago--there may be
>> better techniques available now.

> You can start Java in headless mode too. There are a lot of operations
> you CAN do in headless mode.

Prior to 1.4 you needed xvfb on Unix machines without access to real X
Servers. Windows machines don't have this problem.

Headless AWT support from 1.4:

http://java.sun.com/j2se/1.4.2/docs/guide/awt/AWTChanges.html#headless

Tom Hawtin

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Does javax.swing need X11 on Unix?

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