I code in java. I wrote a keylistener for the frame and it prints all the keystrokes when the frame is active, but when i minimize it or deactivate it, the program obviously stops and no keystrokes are printed. I wanted to make a small game where i enter a key and using the robot class, it presses another set of keys but this game is in flash. any idea as to how i would capture keystrokes when window is deactivated.
edit: I only code in java so is it possible using only java or at most combining it with native machine... i use windows
By its nature, Java is sandboxed by the JVM, so you will have to incorporate some kind of native methods. There already exists a very flexible and helpful library to accomplish this under open source, called JNativeHook. It's very easy to hook in, especially if you're already familiar with Swing event handlers. Same basic concept, except it leverages native code written in C. It supports all of the basic operating systems (Windows, Mac, *Nix).
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So from this question In Java Swing how do you get a Win32 window handle (hwnd) reference to a window? it appears that I can get the window32 handle .
would it be possible for java.awt.Robot to send mouse/keyboard events to that window handle?
sometimes when I am sending keys via Robot, if the window gets minimized, it will start typing into other background irrelevant windows that are open. I want to prevent this by allowing Robot to send keys and mouse events to that specific window of interest.
Would it be possible to achieve the same deal in Mac and Linux as well? be able to send Robot events to those respective specific window handles?
This is a classic problem with Robot. As they have quoted in the other thread, its not possible with pure AWT/Swing. You have to get into sun's internal API or use native code. There is not getting around that problem.
It is exactly because of the problem that you have i.e. make it work across OS's is why Java has not exposed such a control.
It would be useful to know what you are using this for.
My brief requires me to control itunes through a Java Program and must work on either OS X or Windows.
From my research it seems most people's Windows Control uses the Itunes/COM SDK over a COM bridge, and Mac control uses Applescript.
Thing is I can't seem to find a way to develop this to be truely cross platform, because the libraries I need for OSX seems to be inbuilt and non-accessible from windows.
So I was wondering if anyone had a solution, or another cross platform way to control iTunes from either operating system?
If you just need some commands like Play, pause, stop, next etc. you could try just to simulate a global keyPress event and sent the right KeyCode (for the multimedia Keys). In Java you can use JNI to call a simple C program which will simulates a Keypress for you...or you look at the Robot class in Java.
In windows the function is called: keybd_event(keycode,0,0,0);
The only problem is that other programs (if started) would probably also react to the multimedia keypresses.
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.
I want to write a program that responds when I press a certain key on the keyboard. However, there will be a completely unrelated full-screen program running in the foreground and my program won't have the window focus.
So, basically, what I want to do is start my program and have it run in the background, then start the full-screen program. And then I want to be able to get my program to do stuff in the background when I press a certain key.
Is there a way to do this in Java? If not, is there any way at all to do it?
My platform is Windows 7.
A keystroke is an O/S event. You can write a listener in C++ using hooks, then create a JNI interface on top of it.
Lookup MSDN entry for "SetWindowsHookEx" function for hooking procedure.
If you don't want to fuss with JNI, consider implementing the listener in Visual C++ or Visual Basic and cross-compiling the .NET binaries into Java bytecode. Here is a free tool to do that: http://www.ikvm.net/
I'm looking for a push in the right direction. I have a simple chat program, written totally in Java, and am looking for a way to get the Taskbar icons to flash. Preferably in a manner similar to Pidgin, or MSN.
I'm hoping for a platform independent solution, as there are both Linux and Windows users, and preferably totally in Java.
There is unfortunately no way to do this in the standard Swing API. But you could work around it in several ways:
Flash the icon and title of the window (set a timer and change them whenever it fires).
Request focus, then immediately make the window invisible; reverse the process at your preferred interval.
Both techniques are demonstrated in this forums.sun.com thread.
Alternatively, instead of flashing, you could display a message in the system tray using TrayIcon.displayMessage(); that may or may not suit you better, but beware that it may not work cross-platform.