void switchPresentation(){
  if (availablePresentations.size() < 2) {
    return;
  }
  int index=availablePresentations.indexOf(activePresentationDescriptor);
  if (index < availablePresentations.size() - 1) {
    index++;
  }
 else {
    index=0;
  }
  switchPresentation(availablePresentations.get(index));
}

void switchPresentation ( ) { if ( availablePresentations . size ( ) < 2 ) { return ; } int index = availablePresentations . indexOf ( activePresentationDescriptor ) ; if ( index < availablePresentations . size ( ) - 1 ) { index ++ ; } else { index = 0 ; } switchPresentation ( availablePresentations . get ( index ) ) ; }
switch to the next presentation
