simple state switch

gistfile1.java

color redColor; 
color blueColor; 

boolean colorIsRed; 

void setup () {

  redColor = color (255, 0, 0); 
  blueColor = color (0, 0, 255); 

  colorIsRed = false; //default to a blue color
  
}

void draw () {

  //conditional changes the fill color based on the colorIsRed boolean
  if (colorIsRed == true) { 
    fill (redColor);
  } 
  else {
    fill (blueColor);
  } 

  //draw the ellipse
  ellipseMode (CENTER); 
  ellipse (width/2, height/2, 50, 50);
}

void mousePressed () {

  colorIsRed = !colorIsRed; //make colorIsRed equal to whatever colorIsRed is NOT
  println ("colorIsRed is: " + colorIsRed); 
}