StringBuffer behavior in LWJGL
- by Michael Oberlin
Okay, I've been programming in Java for about ten years, but am entirely new to LWJGL. I have a specific problem whilst attempting to create a text console. I have built a class meant to abstract input polling to it, which (in theory) captures key presses from the Keyboard object and appends them to a StringBuilder/StringBuffer, then retrieves the completed string after receiving the ENTER key.
The problem is, after I trigger the String return (currently with ESCAPE), and attempt to print it to System.out, I consistently get a blank line. I can get an appropriate string length, and I can even sample a single character out of it and get complete accuracy, but it never prints the actual string.
I could swear that LWJGL slipped some kind of thread-safety trick in while I wasn't looking.
Here's my code:
static volatile StringBuffer command = new StringBuffer();
@Override
public void chain(InputPoller poller) {
this.chain = poller;
}
@Override
public synchronized void poll() {
//basic testing for modifier keys, to be used later on
boolean shift = false, alt = false, control = false, superkey = false;
if(Keyboard.isKeyDown(Keyboard.KEY_LSHIFT) || Keyboard.isKeyDown(Keyboard.KEY_RSHIFT))
shift = true;
if(Keyboard.isKeyDown(Keyboard.KEY_LMENU) || Keyboard.isKeyDown(Keyboard.KEY_RMENU))
alt = true;
if(Keyboard.isKeyDown(Keyboard.KEY_LCONTROL) || Keyboard.isKeyDown(Keyboard.KEY_RCONTROL))
control = true;
if(Keyboard.isKeyDown(Keyboard.KEY_LMETA) || Keyboard.isKeyDown(Keyboard.KEY_RMETA))
superkey = true;
while(Keyboard.next())
if(Keyboard.getEventKeyState()) {
command.append(Keyboard.getEventCharacter());
}
if (Framework.isConsoleEnabled() && Keyboard.isKeyDown(Keyboard.KEY_ESCAPE)) {
System.out.println("Escape down");
System.out.println(command.length() + " characters polled"); //works
System.out.println(command.toString().length()); //works
System.out.println(command.toString().charAt(4)); //works
System.out.println(command.toString().toCharArray()); //blank line!
System.out.println(command.toString()); //blank line!
Framework.disableConsole();
}
//TODO: Add command construction and console management after that
}
}
Maybe the answer's obvious and I'm just feeling tired, but I need to walk away from this for a while. If anyone sees the issue, please let me know. This machine is running the latest release of Java 7 on Ubuntu 12.04, Mate desktop environment.
Many thanks.
