1Z0-811 Java Class Design 3

Question 1

What is the effect of declaring a method `abstract` in a non-abstract class?

Accepted Answer

Compilation error — the class must also be abstract

Answer

A class containing an abstract method must itself be declared abstract, or a compile error results.

Question 2

Which statement correctly describes constructor chaining using `this()`?

Accepted Answer

`this()` must be the first statement in the constructor

Answer

A `this()` constructor call must appear as the very first statement in the constructor body.

Question 3

Which of the following best describes method overloading?

Accepted Answer

Same method name, different parameter lists in the same class

Answer

Overloading means defining multiple methods with the same name but different parameter signatures in the same class.

Question 4

What does the `instanceof` operator return when the reference is null?

Accepted Answer

false

Answer

`null instanceof AnyType` always evaluates to `false` without throwing an exception.

Question 5

In Java, a static nested class differs from an inner class because it:

Accepted Answer

Does not hold an implicit reference to the outer class instance

Answer

A static nested class has no implicit reference to the enclosing instance, unlike a non-static inner class.

(1Z0-811) Oracle Java SE11 Programmer Practice Test