Java Online Test | Know Your Java Knowledge

All the best for the quiz! - Java Quiz part 6

Q.1 Which interface should be implemented for sorting on basis of many criteria’s?

Comparator

Comparable

Serializable

None

Q.2 Can two threads on same ConcurrentHashMap object access it concurrently

We need to add additional functionality to achieve the same.

Its not possible

Different threads will access different|completely different} segments concurrently

Q.3 What will be the output of the following code -

List l=new ArrayList();

Q.4 Which of those provides a get(in the index) method?

Map

Set

List

All

Q.5 LinkedHashSet implements:
a. Set
b. Cloneable
c. Serializable

a

b

c

All of these

Q.6 What will be the output of the following code -

Followed by Exception

Runtime Exception

Compile time exception

a

Q.7 In WeakHashMap

An entry are automatically removed by garbage collector

Behaves normally like HashMap

An entry are never removed by garbage collector

None

Q.8 A EnumSet

Can use enum and non enum type keys

Cannot use enum type keys

Is specialised Set implementation for use with enum type keys only

None

Q.9 Iterator returned by HashSet is

Fail-fast

Fail-safe

None

Q.10 Iterator returned by CopyOnWriteArraySet is

Fail-fast

Fail-safe

None

Q.11 Iterator returned by TreeSet is

Fail-fast

Fail-safe

None

Q.12 Iterator returned by LinkedHashSet is

Fail-fast

Fail-safe

None

Q.13 Iterator returned by ConcurrentSkipListSet is

Fail-fast

Fail-safe

None

Q.14 Which List is synchronized?

Vector

CopyOnWriteArrayList

All

None

Q.15 Which Set is synchronized?
a. CopyOnWriteArraySet
b. ConcurrentSkipListSet

a

b

All of these

Q.16 What will be the output of the following code -

a
b
a

a
b

Will print a infinite times

a

Q.17 What is the significance of using instanceOf operator and getClass() in equals method?
a. InstanceOf can return true for comparing current class with its subclass as well
b. getClass() can return true only if exactly same class is compared
c. getClass() can return false when compared with subclass

a

b

c

All of these

Q.18 What will be the output of the following code -

11 44

Runtime Exception

Compile time exception

44 11

Q.19 What will be the output of the following code –

0
null

1
null

2
null

3
null

Q.20 What will be the output of the following code -

Compile time exception

a b c d e 1

a b c d e 2

e d c b a -1

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