For questions 3 through 9, state whether each of the statements is true or false
ID: 3715433 • Letter: F
Question
For questions 3 through 9, state whether each of the statements is true or false. If false, explain why.
3. All methods in an abstract class must be declared as abstract methods.
4. Invoking a subclass-only method through a superclass variable is not allowed.
5. If a superclass declares an abstract method, a subclass must implement that method.
6. An object of a class that implements an interface may be though of as an object of that interface type.
7. An interface’s type can be used as an argument’s type in a method.
8. Abstract methods in an interface must use the abstract keyword.
9. Abstract classes do not have constructors.
Explanation / Answer
3. All methods in an abstract class must be declared as abstract methods.
Answer: True
4. Invoking a subclass-only method through a superclass variable is not allowed.
Answer: True
5. If a superclass declares an abstract method, a subclass must implement that method.
Answer: True
6. An object of a class that implements an interface may be though of as an object of that interface type.
Answer: True
7. An interface’s type can be used as an argument’s type in a method.
Answer: True
8. Abstract methods in an interface must use the abstract keyword.
Answer: False
Does not need to mention abstract. by default interfaces will consider
9. Abstract classes do not have constructors.
Answer: False
it can have contructors though it is an abstract class.
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