46 lines
1.4 KiB
Java
46 lines
1.4 KiB
Java
/**
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* Answer to question.
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*
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* # Question 4
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*
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* Q: Now that the Student class uses an animal as pet, can you still use a cat
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* object as the pet of a student? Why or why not?
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*
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* A: Yes, you can. The Student class has a method getPet() that returns the pet
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* which is Animal type.
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*
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* Q: Can you now use a dog object as the pet of a student? Why or why not?
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*
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* A: Yes, you can. But only attributes and methods definded in the Animal class
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* can be accessed. When you do so, the Dog object will be converted to an
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* Animal object. Assign a child object to a parent object is called upcasting
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* in Java. Upcasting is implicit.
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*
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* # Question 5
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*
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* Q: Where are the name and weight of the bird stored? How?
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*
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* A: The Bird class has a private instance variable name and weight which are
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* inherited from the Animal class.
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*
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* Q: Suppose a student has a bird as a pet. Can the student get the altitude of
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* his pet?
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*
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* A: No. The student's pet is an Animal object. The Bird object is a subclass
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* of Animal. getAltitude is only avaliable in Animal object. When we assign a
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* Bird to an Animal variable, upcasting happend and only attributes and methods
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* in the super class can be accessed.
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*
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*/
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public class Start {
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public static void main(String[] args) {
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Cat.testCat();
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Dog.testDog();
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Student.testStudent();
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Animal.testAnimal();
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Bird.testBird();
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Chicken.testChicken();
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LivingThing.testLiving();
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}
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}
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