code: public void setAlpha (float alpha)
      {
          if (alpha < 0.0f) {
              alpha = 0.0f;
  
          } else if (alpha > 1.0f) {
              alpha = 1.0f;
          }
          if (alpha != _alphaComposite.getAlpha()) {
              _alphaComposite = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, alpha);
              if (_mgr != null) {
                  _mgr.getRegionManager().invalidateRegion(_bounds);
              }
          }
      }
docs: Sets the alpha value of this sprite.