Processing3 1.随机行走

class Walker {
  int x;
  int y;
  Walker() {
    x = width/2;
    y = height/2;
  }
  void display() {
    stroke(0);
    point(x,y);
  }
  
  void step() {
    int choice = int(random(4)); //0,1,2,or 3
    if(choice == 0) {
      x++;
    } else if(choice == 1) {
      x--;
    } else if(choice == 2) {
      y++;
    } else {
      y--;
    }
  }
}

Walker walker;
void setup() {
  size(640,360);
  walker = new Walker();
  background(255);
}
void draw() {
  walker.setup();
  walker.display();
}