void advance(double deltaTime){
  for (  Spring spring : mActiveSprings) {
    if (spring.systemShouldAdvance()) {
      spring.advance(deltaTime / 1000.0);
    }
 else {
      mActiveSprings.remove(spring);
    }
  }
}

void advance ( double deltaTime ) { for ( Spring spring : mActiveSprings ) { if ( spring . systemShouldAdvance ( ) ) { spring . advance ( deltaTime / 1000.0 ) ; } else { mActiveSprings . remove ( spring ) ; } } }
update the springs in the system
