I am working on a Java application which has to launch a different application. If I launch the second application using Runtime.getRuntime().exec(), it becomes the active process and its window comes before my application's window. What I really want to do is launch the process in "hidden" mode so that its taskbar entry does not appear and its window is initially invisible or behind my application window. Then my application would make it visible or move it to the front when it is good and ready. Is this possible or am I asking for too much?
This is for a demo. So I am not worried about security issues.
Edit: Daniel's answer has given me an idea. What if I use Powershell to invoke the application instead of CMD.EXE? Will that let me start the app without the window and then bring the window back? I will be using to launch java to launch PowerShell to launch app, but what the heck!
You don't say what this other application is, but I'm assuming that it's one that you have no control over (i.e. you can't give it a parameter option to start up in a minimized mode or similar.) Rather than hide the application you're launching, can you just use the toFront() method on your window after the other application has launched to bring your window in front of the other? And then minimize your window when you want to reveal the other one?
I'm the first to admit it's a bit of a bodged solution, but it might work depending on what you're after.
You cannot provide these parameters, BUT you can use the "start" command (try it in cmd), which supports these parameters. Eventually you have to call it with a cmd.exe shell, but this will work!
Related
How can I disable OS-level keyboard shortcuts (e.g. Alt-Tab, Ctrl-Alt-Left/Right, etc.) on a [Ubuntu] Linux machine? I'm developing a full-screen Java Swing app and don't want the user to be able to task switch away from the program arbitrarily. It's not enough to toggle the "always on top" flag; users mustn't be allowed to switch workspaces, migrate focus or any other such things. The machine must function normally before and after the application is executed. Google says that this will require JNI or JNA but I'm looking for a bit more hand-holding.
There's no point in trying to do this in your application because any of these changes are going to need to be handled by X11 and/or the window manager since those are what respond to the commands. Assuming that you have control of the platform, choose a window manager which supports a kiosk mode. Then use the window manager's settings to start your application and enter kiosk mode.
Options for window managers which can do this include KDE or twm-kiosk.
(And if you don't have control of the platform, you're not likely to be able to have your application intercept things like ctrl-alt-backspace anyway.)
Edit:
In response to a scaled-down version of the question in which he's willing to let things like ctl-alt-backspace go and just wants most of the keys including alt-tab or other similar application switching key combinations, the following should work:
You should be able to do this using XLib's XGrabKeyboard method through JNI. This Java/XLib JNI keypress capture tutorial should be a good starting point. However, it uses XGrabKey which just passively listens for keys and does not prevent other applications from receiving them. You'll instead want to use XGrabKeyboard which actively snags all of the normal keyboard events (which, if the premise of this StackOverflow question is correct, includes the task switching keys).
Note that as a side-effect, key capture in Swing will also probably stop working because your Swing windows are going to be separate from the window you create in C. As such, you will probably have to use your JNI interface to get key presses to your program when needed. (Although I would definitely advise testing it first before writing the code.) You might be able to avoid this if you can get the window using Java AWT Native Interface to get the window ID. (Note that Swing is built on top of AWT, so this will work for Swing.) However, I'm not sure how to do this. It looks like you might be able to navigate the window tree by getting the root window from the Display and going from there to find your Window, but it's all kind of weird. It would be nice if the AWT NI just told you the window ID, but it doesn't look like it does that.
As this warning Reminder: XGrabKeyboard is not a security interface notes, this doesn't make it impossible for other programs to see the keys, but it seems likely that window managers will not be using XQueryKeyMap so it is likely to prevent task switching.
Due to a suite of antivirus and security policies, a java applet I developed for my organization loads very slowly. The problem is not the cache or the applet, but rather it's JVM. When Windows first loads, if I go to command window and enter "java", it will take nearly a minute for the response (the command usage text) to come up. Subsequent commands are responded immediately.
So, one mitigation I can think of is to set all users to run java once as they login. I can either put a shortcut to Start Up folder in the start menu, or create a registry key. If I want this to be as least intrusive as possible (load it in background and in low priority), what's the best way to do this?
Did you consider Windows Task Scheduler and task that starts on windows start-up?
You can add the call to java to the registry, under
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
http://msdn.microsoft.com/en-us/library/aa376977(v=vs.85).aspx
But what about not using java?
I am making an application that will sit in the system tray and open a window when a user clicks it, the problem is I want the application to be run from start up using an exe, adding the application to the system tray without opening a window. but when the user opens the application on their own I want the window to pop up. how can i determine weather the application was run on boot up or by the user?
You can write a class that through JNI you call some windows libraries that has a Enum with all the processes and information about it. This way you find your process and see who executed it. Process Information
You can run the main method of your class with different args or have two different classes with main methods for each use case.
I am creating a program using Java Sockets in which I capture the client desktop and send messaging to client. Its working properly but now I want to block Client applications like Notepad, MS-Word, etc.
How can I do this?
Thanks.
It is hard to do using pure java API.
I do not know what do you mean when you say "block". The easiest way is to check from time to time running processes and kill one named "notepad" by executing taskkill from java.
If you wish to achieve effect of inactivity of application, i.e. user sees the notepad but cannot type you can do the following.
You have to check which application is on front. There is no clean pure java solution for this but you can probably write VBScript or JScript that does this task and run it from java. Once you detected that notepad is on top create transparent window (or even probably half-transparent window) that occupies full screen. Bring it on top. User will not be able to type into notepad because your window is on top but will see it.
Here is reference how to create transparent windows: http://java.sun.com/developer/technicalArticles/GUI/translucent_shaped_windows/
Good luck.
Is there any option which i can use to Control Window State of another App. from a Java Application .
Like if i need to minimize or maximize another app. window on Ubuntu Enviroment (if it's matter's im using Gnome Window Manager).
Bests
Two bad options:
1) use java.awt.Robot to click the appropriate coordinates where the window is. (You have to hard code these)
2) use jni