public void removeValue(Comparable key){
  int index=getIndex(key);
  if (index < 0) {
    throw new UnknownKeyException("The key (" + key.toString() + ") is not recognised.");
  }
  removeValue(index);
}

public void removeValue ( Comparable key ) { int index = getIndex ( key ) ; if ( index < 0 ) { throw new UnknownKeyException ( "The key (" + key . toString ( ) + ") is not recognised." ) ; } removeValue ( index ) ; }
removes a value from the collection .
