Develop Reference

Swapping JButtons in Java

I made an array list of strings and assigned an image to each string. Then, I randomized these images. I want to now make a method that swaps one button to the button adjacent to it, but I have no idea how to do this. Any suggestions about how to go about it? Thanks

First suggestion: Don't. Don't swap JButtons as you're making things much harder than they need to be. Instead if possible swap images or more specifically ImageIcons, and this can be easily done using the JButton method, setIcon(...).
It almost sounds as if you're trying to create a memory game, and if so there are plenty of examples of just this sort of thing to be found on this site, at least one created by me.
As always in these sorts of things, first concentrate on the program's model, that is, its logical underpinnings, and only after getting that working, apply it to the program's view or its GUI representation of the model's state.

Java - Best way to go about collecting PAST values

I have a simple Mario game and have key events that decide different animations and movements of the player.
They are:
Move Left
Move Right
Jump Left
Jump Right
As you can imagine, the player will only be able to play the jump right animation if he is moving right and is/has pressed the jump button
The issue I have come across is that only 1 key value may be sent at once. This makes if statements with && conditions useless.
Here was the code that did not work:
if(key == KeyEvent.VK_LEFT) {
if(distanceTraveled<300)dx=-5; else dx=-4;
if(key == KeyEvent.VK_UP)
player = jump_L_anim.getImage();
else
player = walk_L_anim.getImage();
} else {
if(distanceTraveled<300)dx=5; else dx=4;
if(key == KeyEvent.VK_UP)
player = jump_R_anim.getImage();
else
player = walk_R_anim.getImage();
}
Simple enough, I realized that there are solutions to this and began attempting to figure out the key pressed before the current one.(this key could not be equal to the one currently pressed).
This would allow an if statement such as
if key==right && lastKey == up
run jump_R animation
I managed to be able to grab the last key, but not the last key that was not a repeat.
I felt really confused and decided to watch this missile guidance for dummies video. That made me even more confused, In my boring accounting class I figured out the solution must be to store all previous values in an array, then I would loop through the values from the last to the beginning. I would continue this until the numbers would not continue. The number where the repetition stops is the last value i am looking for.
For anyone confused by this take a look at these console readings of key movements
48
48
48
49
49
49
49
47
47
47
The number I am looking for in this situation is 49. That is because it was the last key pressed that is not the current key.
Is my logic behind this issue correct? How would you solve this issue? I prefer not working with arrays if there is a simple variable only solution available. I am looking for the fastest and most efficient logic.

Perhaps you can store which keys are held down at the moment into an HashSet, and the if statement would be something like:
if (keyCodeSet.contains(x) && keyCodeSet.contains(y))
where x and y are the key numbers you want. When the keys are released, you simply remove them from the set.

You should keep track of when the keys are released. If up is never released, you know it's still being held. If right is never released, you know it's still being held. Each update, you can check if both are down and react accordingly.

It's actually totally simple:
Listen to both keyPressed and keyReleased
use a Set<Key>1 or just 4 variable for the keys you're interested in
when a key gets pressed set, add it to the set
when a key gets released, remove it
On any key press, check if the other key is there. This way you can distinguish "Up+Right" from "Right+Up" if you want to.
1 Key may be Integer or whatever representation you prefer.

Processing/Java - Key pressed/Key released

I'm building an application on Processing using NyARToolkit, but my question is not directly about NyArToolkit but about a key released() method.
The thing is, I show a card and then I can do a few things if I press different keys. I press "X" and it shows one thing, I press "Y" and it shows another thing. The problem is, it shows the info from the last key pressed all the time.
If I change my AR card, it will immediatly show the info from the last key pressed. I would like to do something to release the key, something like: just show while i'm pressing the key, or have an "ESC" to stop showing everything.
I've been reading about the keyreleased() method but I didn't figured it yet out to put it to work.
By the way my method is like this:
if(key == "c") then
else if(key =="d") then...

How about a boolean keeping track wether you've pushed something
private boolean buttonIsPressed = false;
and inside your keyPressed
buttonIsPressed = true;
and inside your keyReleased
buttonIsPressed = false;
This way you can keep track wether it's pressed or not, using a String you can also keep track which button is being held by initializing it in your keyPressed and making it null in your keyReleased.
If I missunderstood your question let me know.
EDIT:
Reading your edit, you're making quite a big mistake there, make sure to use .equals to compare strings so if(key.equals("c"))
Again, your question is not quite clear for me, so if I'm wrong, excuse me.

ParkingSimulation infinite while loop crisis

I'm a beginning computer science student and we've been asked to complete a project that animates random generated car objects moving to randomly generated parking spots on a city map grid. I've developed a GUI for the buttons, text fields, and text areas. Everything works as required except for at the end of the animation, when all cars have reached parking spots, I need to display analytics in my JTextArea. My buttons are set up properly and I will show you where the code takes place below:
else if (e.getSource() == start) {
setAnimate(true);
if(simulator.simulationFinished()) {
createAnalytics();
}
}
So here I have implemented an action listener on the button "start" that begins the animation. Currently it:
currently it begins the animation and all the cars travel to the parking spots as intended.
it displays analytics that are derived from before the animation began (Analytics include: car ID, number of moves, average number of spots tried, average distance travelled)
then the animation will conclude.
If I press the start button again it will display the proper analytics.
I know that in order for the program to display the right analytics the moment the program finishes I most likely need a while loop, however I haven't been able to dream anything up that will not create an infinite loop and require me to manually terminate the program via console.
while(!simulator.simulationFinished()) {
if(simulator.simulationFinished() == true)break; {
createAnalytics();
}
}
I've also tried this among several hundred other variations of all the loops in existence. Following from my logic, I need the while loop so that it will keep checking to see if the simulation is finished so that I can execute my method that generates analytics, but if don't give the while loop something to do it just goes on forever and crashes. I'm at a loss, any help would be appreciated. Thanks.

First: no, you don't need a while loop necessarily. You could use the observer pattern instead (for example) and your object would be notified as soon as the simulation had finished. As to your question: the if inside the while is obviously superfluous (as is the == true). The real problem seems to be that simulator.simulationFinished() never returns true. Could you post the code of that function and the code (and any code that directly influences the return value of it)?

Without going into details, there's a serious problem with your while loop.
See, it loops as long as simulator.simulationFinished() returns false.
However, within the loop, you check for the opposite - which will never happen.
I would recommend using listeners of some sort, although the requirement is not clear enough for me to advise any further.

Slick2D Movement Issue

So, I converted a game to Slick2D. The movement is broke, and I am at a loss. Before, we used KeyPressed and keyReleased methods, but now with Slick2D movement isn't working right.
Yea, nothing has gone right with converting to Slick2D. First the launcher, which I had a help topic on before, and now this. Though, the other topic was an issue with WebStart hating code.
You can only move right, using A. And you can't stop moving. Am I using the right methods? How can I fix it? Any help is greatly appreciated!
Here is a PasteBin link to the code, if it helps! http://pastebin.com/GRH86Yuw

I'm a fan of Slick, and I'd be happy to help.
The fundamental difference is that Slick is a polling model, not an event-driven model when it comes to input. Basically, in your logic update method you loop through the keys bound to your events, and check to see if any of the keys are currently pressed, and then trigger those events. For a number of reasons that I can go into if you like, polling tends to work better for games, especially with a large number of keys. It's just a different way of doing things, an not that complicated. The biggest upside is that you get centralized input processing a single method, instead of having it spread across multiple KeyListener instance objects.
If you want to look at Pedestrians - a simple pedestrian sim implemented in Slick - you can see an example of how to handle input in Slick.
Specifically, I handle input in this file (lines 192-295), inside the processInput method. Basically, you pass in a reference to the GameContainer object (the Slick object that contains your game), and from that you can get an instance to the Input instance that will allow you to check which keys are pressed, what mouse buttons are clicked, etc.