Question on Data Type-Enums
Question on Data Type-Enums
1. What is the order of variables in Enum?
a) Ascending order
b) Descending order
c) Random order
d) depends on the order() method
Answer: a
Explanation: The compareTo() method is implemented to
order the variable in ascending order.
2. Can we create an instance of Enum outside of Enum
itself?
a) True
b) False
Answer: b
Explanation: Enum does not have a public constructor.
3.
enum Season {
WINTER,
SPRING, SUMMER, FALL
};
System.out.println(Season.WINTER.ordinal());
a) 0
b) 1
c) 2
d) 3
Answer: a
Explanation: ordinal() method provides number to the
variables defined in Enum.
4. If we try to add Enum constants to a TreeSet, what
sorting order will it use?
a) Sorted in the order of declaration of Enums
b) Sorted in alphabetical order of Enums
c) Sorted based on order() method
d) Sorted in descending order of names of Enums
Answer: a
Explanation: Tree Set will sort the values in the order
in which Enum constants are declared.
5. What is the output of below code snippet?
class A
{
}
enum Enums extends A
{
ABC, BCD, CDE,
DEF;
}
a) Runtime Error
b) Compilation Error
c) It runs successfully
d) EnumNotDefined Exception
Answer: b
Explanation: Enum types cannot extend class.
6. What is the output of below code snippet?
enum Levels
{
private TOP,
public MEDIUM,
protected
BOTTOM;
}
a) Runtime Error
b) EnumNotDefined Exception
c) It runs successfully
d) Compilation Error
Answer: d
Explanation: Enum cannot have any modifiers. They are
public, static and final by default.
7. What is the output of below code snippet?
enum Enums
{
A, B, C;
private Enums()
{
System.out.println(10);
}
}
public class MainClass
{
public static
void main(String[] args)
{
Enum en =
Enums.B;
}
}
a)
10
10
10
b) Compilation Error
c)
10
10
d) Runtime Exception
Answer: a
Explanation: The constructor of Enums is called which
prints 10.
8. Which method returns the elements of Enum class?
a) getEnums()
b) getEnumConstants()
c) getEnumList()
d) getEnum()
Answer: b
Explanation: getEnumConstants() returns the elements of
this enum class or null if this Class object does not represent an enum type.
9. Which class does all the Enums extend?
a) Object
b) Enums
c) Enum
d) EnumClass
Answer: c
Explanation: All enums implicitly extend java.lang.Enum.
Since Java does not support multiple inheritance, an enum cannot extend
anything else.
10. Are enums are type-safe?
a) True
b) False
View Answer
Answer: a
Explanation: Enums are type-safe as they have own
name-space.
Question on Data Type-Enums
Reviewed by Unknown
on
February 24, 2019
Rating:
Reviewed by Unknown
on
February 24, 2019
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