مساعده في الجافا x_x

[أنفآإس الورد..}]

السلام عليكم ,,
ممكن احد يشرح لي هذا البرنامج ايش يبغى,,
انافاهمته بس مو عاارفه الطريقه اللي تبيها الاستااذه في شرحها للبرنامج ,,
فاياليت احد يسااعدني واكون شااكره لكم,,

Design and implement a class called Sphere that contains instance data that represents the sphere's diameter. Define the Sphere constructor to accept and initialize the diameter, and include getter and setter methods for the diameter. Include methods that calculate and return the volume and surface area of the sphere (Volume= 3/4 π r3 , area = 4 π r2 ). Include a toString method that returns a one-line
deion of the sphere. Create a driver class called MultiSphere, whose main method instantiates and updates several (at least 5) Sphere objects.