Java Online Quiz – Test Your Knowledge in 7 Min. Only

1. Java Online Quiz

Earlier we saw Java Quiz Part 1. This Java online quiz will help you to clear your java concepts and also check your java knowledge. It will increase your confidence while appearing for Java interview. Answer all these Java online quiz questions and follow the relevant link for better Java understanding.

Java Online Quiz 2018 – Test Your Knowledge

So, ALL THE BEST!! for this Java Online Quiz.

Q.1 What guarantees type-safety in a collection?

Generics

Abstract classes

Interfaces

Collection

Correct! Wrong!

Q.2 HashSet internally uses?

Set

HashMap

List

Collection

Correct! Wrong!

Q.3 The most used interfaces from the collection framework are?

List

Map

Set

Correct! Wrong!

Q.4 The root interface of Java collection framework hierarchy is -

Collection

Root

Collections

List/Set

Correct! Wrong!

Q.5 Which of those is synchronized?

ArrayList

LinkedList

Vector

None of these

Correct! Wrong!

Q.6 ArrayList implements that of the following?

List

RandomAccess

Cloneable

All of these

Correct! Wrong!

Q.7 Which of those permits the storage of the many null values?

Set

List

None of these

All of these

Correct! Wrong!

Q.8 nextIndex() and previousIndex() are methods of which interface?

IndexIterator

Iterator

ListIterator

NextPreviousIterator

Correct! Wrong!

Q.9 Vector extends that of these?

ArrayList

LinkedList

AbstractList

None

Correct! Wrong!

Q.10 LinkedList implements?

Deque

List

None of the above

Both of the above

Correct! Wrong!

Q.11 In Iterator, nextElement() method of Enumeration has been changed to:

next()

getNext()

returnNext()

name remains same

Correct! Wrong!

Q.12 Enumeration returned by Vector is?

fail-fast

fail-safe

none

Correct! Wrong!

Q.13 From Java five onwards, that one among these is suggested to replace Hashtable?

ConcurrentHashMap

HashMap

ConcurrentHashtable

None

Correct! Wrong!

Q.14 Which doesn't permit to store a null value?

TreeSet

LinkedHashSet

HashSet

None

Correct! Wrong!

Q.15 Iterator returned by Vector is?

fail-fast

fail-safe

none

Correct! Wrong!

Q.16 What describes an algorithm performs in best, average or worse case scenarios?

Big-B

Big-O

Big-Data

Big-N

Correct! Wrong!

Q.17 State the search time complexity of an ordered array.

O(n)

O(1)

O(log n)

O(n-1)

Correct! Wrong!

Q.18 Name the map that should be kept in a multi-threading environment to keep up the natural order of keys?

ConcurrentHashMap

ConcurrentSkipListMap

ConcurrentMap

Correct! Wrong!

Q.19 TreeMap implements?

Dictionary

HashMap

AbstractMap

NavigableMap

Correct! Wrong!

Q.20 Which list class should be most popular in a multi-threading environment, considering performance constraint?

Vector

CopyOnWriteArrayList

ArrayList

ConcurrentArrayList

Correct! Wrong!

See also – 

Java Quiz Part 3

Technical Java Quiz Questions