D.Implement the class Fleet that has as data an array of n aircrafts.

a) Write the constructor, which creates an empty collection of Aircrafts. The size of this array is passed as a parameter to the constructor of the class Fleet

b) Write the method addAircraft (A: Aircraft) which adds a CivilAircraft or a Fighter object to the collection.

c) Write the method aircraftAt(ind: int) which returns the aircraft in the collection at the index ind if the index is valid. Otherwise, it should return null.

d) Write the method fastestAircraft ( ) which returns the aircraft with the max speed in the collection.

> Comparable + compareTo(o:E):int 1 Aircraft - speed: double + Aircraft(speed: double) +toString():String + allowedWeight(): double Fleet - aircrafts: Aircraft[] + Fleet(size: int) + addAircraft (a: Aircraft): void + aircraftAt(ind:int): Aircraft +fastestAircraft(): Aircraft Fighter -armingWeight: double +Fighter(speed:double, armingWeight:double) +toString():String CivilAircraft -capacity: int +CivilAircraft(speed:double,capacity:int) +toString():String D. (20 pts] Implement the class Fleet that has as data an array of n aircrafts. a) Write the constructor, which creates an empty collection of Aircrafts. The size of this array is passed as a parameter to the constructor of the class Fleet b) Write the method addAircraft (A: Aircraft) which adds a CivilAircraft or a Fighter object to the collection. c) Write the method aircraftAt(ind: int) which returns the aircraft in the collection at the index ind if the index is valid. Otherwise, it should return null. d) Write the method fastestAircraft () which returns the aircraft with the max speed in the collection