/**
  * Sets the compression strategy. Strategy is one of DEFAULT_STRATEGY, HUFFMAN_ONLY and FILTERED.
  * For the exact position where the strategy is changed, the same as for setLevel() applies.
  *
  * @param stgy the new compression strategy.
  */
 public void setStrategy(int stgy) {
   if (stgy != DEFAULT_STRATEGY && stgy != FILTERED && stgy != HUFFMAN_ONLY)
     throw new IllegalArgumentException();
   engine.setStrategy(stgy);
 }