2D grid array question

Processing Coding Questions
14

I moved the keyPressed() to the main program, but now am getting error y variable does not exist.
Also, I’m not sure what below quote means…

Button [][] myButtons;

// Number of columns and rows in the grid
int num = 10;
int cols = num, rows = cols;

color background = color (random(255), random(255), random(255));

void setup() {
  size(500, 500);

  int x = (width/num)/2, y = x;

  myButtons = new Button[cols][rows];
  for (int i = 0; i < cols; i++) {
    for (int j = 0; j < rows; j++) {
      // Initialize each object
      myButtons[i][j] = new Button (x+ i*(width/cols), y+ j*(height/rows), 
        color (random(255), random(255), random(255)), // random colors
        color (random(255), random(255), random(255)), // new random colors when mouseOver
        (width/num));
    }
  }
}

void draw() {

  background(background);


  for (int i = 0; i < cols; i++) {
    for (int j = 0; j < rows; j++) {
      myButtons[i][j].mouseOver();
      myButtons[i][j].display();
    }
  }
}
void keyPressed() {
  
      if (key == CODED) {
        if (keyCode== UP) {
          y = y+1;
        } else if (keyCode== DOWN) {
          y = y-1;
        } else if (keyCode== LEFT) {
          x = x-1;
        } else if (keyCode== RIGHT) {
          x = x+1;
        }
      }
    }