Java Multiple Choice Questions & Answers – A Door to Success

1. Online Java Multiple Choice Questions

Earlier, we have discussed Java MCQ’s Part 3. Today, we have come with Java multiple choice questions. These Java multiple choice questions will help you to test yourself in Java Programming Language. Answers all these java multiple choice questions and follow the link to get a better understanding.

So, let’s start Java Multiple Choice Questions.

Java Multiple Choice Questions & Answers

Q.1 Iterator returned by Hashtable on key, value and entry are?

Fail-fast

Fail-safe

None of the both

Correct! Wrong!

Q.2 Iterator returned by ConcurrentHashMap on key, value and entry is?

Fail-fast

Fail-safe

None of the both

Correct! Wrong!

Q.3 Iterator returned by LinkedHashMap on key, value and entry is?

Fail-fast

Fail-safe

None of the both

Correct! Wrong!

Q.4 Iterator returned by TreeMap on key, value and entry is?

Fail-fast

Fail-safe

None of the both

Correct! Wrong!

Q.5 Iterator returned by ConcurrentSkipListMap on key, value and entry is?

Fail-fast

Fail-safe

None of the baove

Correct! Wrong!

Q.6 Which Set implementation is sorted and synchronized?

LinkedHashSet

ConcurrentSkipListSet

TreeSet

CopyOnWriteArraySet

Correct! Wrong!

Q.7 TreeMap -

Doesn't enable null key

Allow several null values

Both the above

Correct! Wrong!

Q.8 What will be the output of the following code –

{11=a}

{11=a, 12=b}

UnsupportedOperationException

Compile time exception

Correct! Wrong!

Q.9 What will be the output of the following code -

Runtime Exception

Compile time exception

2
{11=bmw, null=fer}

Correct! Wrong!

Q.10 What will be the output of the following code -

3
null

2
null

1
null

0
null

Correct! Wrong!

Q.11 What will be the output of the following code -

1
null

2
emp1 OVERRIDDEN

3
null

1
emp1 OVERRIDDEN

Correct! Wrong!

Q.12 What will be the output of the following code -

1
emp1 OVERRIDDENQ

2
emp1 OVERRIDDEN

1
null

3
null

Correct! Wrong!

Q.13 What will be the output of the following code -

1
true
1
[1, 3, 4]

3
true
1
[1, 3, 4]

3
false
1
[1, 3, 4]

1
false
1
[1, 2, 4]

Correct! Wrong!

Q.14 Which Map is synchronized?

Hashtable

ConcurrentSkipListMap

ConcurrentHashMap

All of the above

Correct! Wrong!

Q.15 concurrentSkipListMap permits

One null key

Many null values

None of the above

Correct! Wrong!

Q.16 What should we use get operations are more?

ArrayList

LinkedList

Any

Correct! Wrong!

Q.17 Complexity of ArrayList get method

O(n-1)

O(n)

O(1)

O(2n)

Correct! Wrong!

Q.18 Which is sorted by natural order?

LinkedHashSet

TreeSet

HashSet

None of the above

Correct! Wrong!

Q.19 Which of these maintains insertion order?

List

Set

Correct! Wrong!

Q.20 Which maintains insertion order?

TreeSet

HashSet

LinkedHashSet

Correct! Wrong!

See also –
java Multiple Choice Question Part 2
Free java Quiz part 1