Free Java Quiz Questions With Answers – Prepare Yourself For Interviews

1. Online Java Quiz Questions

Today, we will move towards Java quiz questions. These Java quiz questions will brush up your concepts of java and prepare you to face Java interview. This Java quiz contains multiple choice questions for java. Answers to all these Java quiz questions and follow the relevant link to get the deeper knowledge of Java.

So, let’s start exploring Java Quiz Questions.

Free Java Quiz Questions With Answers

Q.1 Which Set class should be most popular in a multi-threading environment, considering performance constraint?

HashSet

ConcurrentSkipListSet

LinkedHashSet

CopyOnWriteArraySet

Correct! Wrong!

Q.2 Which Map class should be most popular in a multi-threading environment, considering performance constraint?

Hashtable

CopyOnWriteMap

ConcurrentHashMap

ConcurrentMap

Correct! Wrong!

Q.3 Which allows the removal of elements from a collection?

Enumeration

Iterator

Both

None of the above

Correct! Wrong!

Q.4 What will be the output of given code

Compile time exception

3 2 1

1 2 3

2 3 1

Correct! Wrong!

Q.5 What will be the output of the following code

1 2 3

1 followed by exception

Compile time exception

321

Correct! Wrong!

Q.6 What will be the output of given code

a followed by ConcurrentModificationException

a b c

a b

a c

Correct! Wrong!

Q.7  What will be the output of the following code

[null, 1]

[1]

[null, 1, 1, null]

Runtime Exception

Correct! Wrong!

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

{a=ferrari}

{a=ferrari, a=audi}

Runtime Exception

{a=audi}

Correct! Wrong!

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

Runtime Exception

[1]

[null, 1]

{a=ferrari}

Correct! Wrong!

Q.10 Which permits the removal of elements from a collection?

Enumeration

Iterator

None of the above

Correct! Wrong!

Q.11 The Comparator interface contains the method?

compareWith

compareTo()

compare()

Correct! Wrong!

Q.12 Which of those is synchronized?

TreeMap

HashMap

Hashtable

Correct! Wrong!

Q.13 Which offers the best performance?

TreeMap

HashMap

LinkedHashMap

Correct! Wrong!

Q.14 Which of these is the most popularly used class as a key in a HashMap?

String

Integer

Double

All of the above

Correct! Wrong!

Q.15 What should we use when add and remove operations are more frequent than get operations

LinkedList

ArrayList

Vector

Correct! Wrong!

Q.16 Iterator returned by ArrayList is?

Fail-fast

Fail-safe

None of the above

Correct! Wrong!

Q.17 Iterator returned by LinkedList is?

Fail-fast

Fail-safe

None of the above

Correct! Wrong!

Q.18 Iterator returned by CopyOnWriteArrayList is?

Fail-fast

Fail-safe

None of the above

Correct! Wrong!

Q.19 Iterator returned by HashMap on key, value and entry are?

Fail-fast

Fail-safe

None of the above

Correct! Wrong!

See also – 

Java Quiz Part 4

Java Quiz Part 5