1Z0-819 Core APIs & Data Manipulation

Question 1

Which Java package is primarily used for collections?

Accepted Answer

java.util

Answer

java.lang

Answer

java.io

Answer

java.net

Question 2

What does the List interface provide?

Accepted Answer

Ordered collection that allows duplicates

Answer

Sorted elements with no duplicates.

Answer

An unordered collection of unique elements.

Answer

Randomized collection of values.

Question 3

How does the HashMap store data?

Accepted Answer

Using key-value pairs

Answer

Sequentially with index values.

Answer

In a tree structure.

Answer

As a continuous memory block.

Question 4

What is the function of the Stream API?

Accepted Answer

To process collections with functional-style operations

Answer

To build user interfaces.

Answer

To create threads.

Answer

To handle network connections.

Question 5

Which method is used to add an element to a List?

Accepted Answer

add()

Answer

insert()

Answer

append()

Answer

push()

Question 6

What is the default sorting method in Java?

Accepted Answer

Natural order using Comparable

Answer

Random sort.

Answer

Lexicographical order.

Answer

Reverse alphabetical.

Question 7

Which class is used to manipulate strings?

Accepted Answer

StringBuilder

Answer

StringBuffer

Answer

String

Answer

CharSequence

Question 8

What is the result of calling size() on an ArrayList?

Accepted Answer

Returns the number of stored elements

Answer

Returns -1.

Answer

Returns the array length.

Answer

Returns the memory usage.

Question 9

How do you remove an element from a List by index?

Accepted Answer

remove(index)

Answer

delete(index)

Answer

pop(index)

Answer

unset(index)