Processing button class

Button.pde

class Button {
  private float x, y, w, h;
  private String label;
  private Runnable onClickRunnable;

  public Button(float x, float y, float w, float h, String label, Runnable onClickRunnable) {
    this.x = x; this.y = y; this.w = w; this.h = h;
    this.font = createFont("Tahoma", 13, true);
    this.label = label;
    this.onClickRunnable = onClickRunnable;
  }

  public void draw() {
    runActions();

    drawRectangle();
    drawText();
  }

  private void drawRectangle() {
    // not setting cursor(HAND), because processing makes it ugly
    if (isMouseOver()) {
      fill(212, 218, 240, 40);
    } else {
      fill(212, 218, 240, 20);
    }

    noStroke();
    rect(x, y, w, h, 3);
  }

  private void drawText() {
    fill(200);
    noStroke();
    textFont(font);
    textAlign(CENTER, CENTER);
    text(label, x + w/2, y + h/2);
  }

  private void runActions() {
    if (mousePressed && isMouseOver()) {
      onClickRunnable.run();
    }
  }

  public boolean isMouseOver() {
    boolean inX = mouseX >= x && mouseX <= x + w;
    boolean inY = mouseY >= y && mouseY <= y + h;
 
    return inX && inY;
  }
}

index.pde

Button myButton = new Button(
  x, y,
  buttonW, buttonH,
  "Press me",
  new Runnable() { public void run() { println("Hi babe"); } }
);
void setup() {
  size(600, 600, P3D);
  pixelDensity(2);
  noFill();
}
void draw() {
  myButton.draw();
}