code: public void pairsSortedByKey(final IntArrayList keyList, final ObjectArrayList valueList) {
  	keys(keyList);
  	keyList.sort();
  	valueList.setSize(keyList.size());
  	for (int i=keyList.size(); --i >= 0; ) {
  		valueList.setQuick(i,get(keyList.getQuick(i)));
  	}
  }
docs: Fills all keys and values <i>sorted ascending by key</i> into the specified lists.
  Fills into the lists, starting at index 0.
  After this call returns the specified lists both have a new size that equals <tt>this.size()</tt>.
  <p>
  <b>Example:</b>
  <br>
  <tt>keys = (8,7,6), values = (1,2,2) --> keyList = (6,7,8), valueList = (2,2,1)</tt>
  
  @param keyList the list to be filled with keys, can have any size.
  @param valueList the list to be filled with values, can have any size.