Boolean variable help!

Programming Questions

TheGamers..

in Programming Questions • 2 years ago

I have defined a boolean variable "retro" false and I have my code setup so that if you press and hold the "r" key it will set it to "true" and if you release the "r" key it will set it to false and it will print if the variable is true or false. Well, when I ran the sketch it was already saying retro equaled true before I had pressed anything. Here are a few snippits of code if you need them.

boolean retro = false;
void ball() {

  if (retro = false) {

   smooth();

   noStroke();

   fill(255,50);

   rectMode(CORNER);

   stroke(0);

   rect(0,0,width,height);

   fill(0);

   ellipse(mouseX,mouseY,10,10);

  }

  if (retro = true) {

   noSmooth();

   fill(0,50);

   rectMode(CORNER);

   rect(0,0,width,height);

   stroke(0,255,0);

   ellipse(mouseX,mouseY,10,10);

  }

}

void keyPressed() {

      if (key == 'r' || key == 'R') {

   retro = true; //Enables retro mode.

   }

  }

void keyReleased() {

  if (key == 'r' || key == 'R') {

   retro = false; //Disables retro mode.

  }

}

I've been looking over my code for awhile and I couldn't find the reason why it isn't working... If you need anything else feel free to ask. I won't be able to respond, though, for a five to six hours because of school.

Also, if you could help me out with a previous problem, that would be just great.

http://forum.processing.org/topic/increasing-memory

Thanks,

TheGamersHaven

Replies(9)

quarks

Re: Boolean variable help!

2 years ago

In the ball() method you have two if statements to check the value of retor and you have

if (retro = true) {

when it should be

if (retro == true) {

It is the difference between an assignment statemnet (=) and a test (==)

PhiLho

Re: Boolean variable help!

2 years ago

The only case where Java doesn't protest for an assignment in a if...

Note: the second test can be replaced by a simple else.

TheGamers..

Re: Boolean variable help!

2 years ago

@quarks Thanks, it works now, but the only problem is that it doesn't turn retro when I press the "r" key...

@phi.lho Thanks for your response, I originally had that, just when it didn't work I changed it and forgot to put it back

Thanks,

TheGamersHaven

PhiLho

Re: Boolean variable help!

2 years ago

Beware that the OS will repeat the keyPressed event. Here it isn't important, but it might have side effects in some cases.
You also must have a draw() method, even if it is empty, for these events to be fired.

Side note on original error: beside the redundancy it implies, that's one of the reasons why I say to just use booleans for what they are: no need to test them for equality. if (retro) or if (!retro) is more than enough.

TheGamers..

Re: Re: Boolean variable help!

2 years ago

Thanks for your response, I know that it will repeat the keyPressed event, It's alright.

I do have a draw method, I might not have said it, but these were only a few snippits of code. So, you're saying I should use (retro) or (!retro) whenever using boolean? I changed the if (retro == false)and if (retro == true) To the (retro) and (!retro) and now it acts like it's supposed to. But, it doesn't switch to retro when I press the "r" key... I really don't know why.... How my sketch should work is that if you press and hold the "r" key, it will enable retro mode and that will result in every shape having a green outline, no smooth, and the background and shape fill will be black. If you let go of the "r" key, it will disable retro mode, resulting in the background turning white again and the stroke will be black and smooth will return. It acts like retro is always activated... I keep looking over the code and can't see anything that could result in this behavior.

Thanks,

TheGamersHaven

PhiLho

Re: Boolean variable help!

2 years ago

Debugging the Processing way: add a println(retro) in the key event handlers, to see if the value is correctly toggled.
Perhaps add another println() to see if ball() is called.

TheGamers..

Re: Re: Boolean variable help!

2 years ago

I added the debugging and it initially says that retro is false and that it is not running, which is good, but if you press the "r" key it still doesn't do anything. Is this command valid in setting retro to true?

void keyPressed() {
if (key == 'r' || key == 'R') {
retro = true; //Enables retro mode.
}
}

I'm really stuck.... it calls ball constantly in the draw function and I have all the if keyPressed() and such and the boolean variable...

TheGamersHaven

quarks

Re: Boolean variable help!

2 years ago

The keyPressed code seems fine, based on your description of how the program should work I have modified the code that has been provided and added a setup and draw and this seems to do what you want.

boolean retro = false;
void setup() {
size(400,400);
cursor(CROSS);
}
void draw() {
if(retro) {
background(0);
noSmooth();
}
else {
background(255);
smooth();
}
ball();
}
void ball() {
if (retro) {
noFill();
stroke(0,255,0);
}
else {
noStroke();
fill(0);
}
ellipse(mouseX,mouseY,10,10);
}
void keyPressed() {
if (key == 'r' || key == 'R') {
retro = true; //Enables retro mode.
}
}
void keyReleased() {
if (key == 'r' || key == 'R') {
retro = false; //Disables retro mode.
}
}

TheGamers..

Re: Re: Boolean variable help!

2 years ago

*EDIT*

Guys.... Thanks for all your help, but I made a stupid mistake that was right in front of me... one of the ifPressed key "r" commands was inside of another command I had...

Sorry for wasting all of your time, all of your willingness to help was greatly appreciated.

Thanks again and for being patient with my ignorance,

TheGamersHaven

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