Java
Multiple Choice Questions

James Gosling

Dennis Ritchie

Bjarne Stroustrup

Guido van Rossum

1991

1995

1997

2000

Oak

Green

Java

Coffee

Microsoft

IBM

Sun Microsystems

Oracle

Java 17

Java 21

Java 22

Java 23

.java

.class

.jar

.jvm

int

float

String

boolean

8 bits

16 bits

32 bits

64 bits

char

String

Character

byte

true

false

null

0

const

final

static

constant

-128 to 127

-32768 to 32767

-2147483648 to 2147483647

0 to 65535

2

1

0

2.5

&

&&

|

||

3.33

3

3.0

4

instanceof

typeof

getClass

is

Left to right

Right to left

Both

None

Whether an object is an instance of a specific class

The size of an object

The memory address of an object

The class name of an object

break

continue

return

exit

Yes

No

Error

None

for

while

do-while

All of these

To implement multi-way branching

To loop until a condition is met

To define a method

To declare variables

Yes, from Java 7 onwards

No

Only in Java 8

Only with numbers

012

0123

123

No output

Wrapping data and methods into a single unit

Creating multiple methods with the same name

Inheriting properties from parent class

Hiding implementation details

extends

implements

inherits

super

Ability to take many forms

Creating multiple objects

Defining multiple constructors

Using interfaces

super

this

parent

base

Multiple methods with same name but different parameters

Multiple methods with same name and same parameters

Methods in different classes

Methods with different return types

Redefining a method in child class

Defining multiple methods

Calling a method from parent

Using abstract methods

A class that cannot be instantiated

A class with only static methods

A class with private constructors

A class without any methods

A blueprint for classes that defines abstract methods

A concrete class

A method signature

A package

1

0

-1

Any

int[] arr;

int arr[];

Both A and B

array int arr;

1

2

3

Error

arr.length

arr.size()

arr.length()

len(arr)

int[][] arr = new int[3][4];

int arr[][] = new int[3][4];

Both A and B

int arr[3][4];

Returns null

Throws ArrayIndexOutOfBoundsException

Returns 0

Compilation error

Yes

No

Only if using StringBuilder

Only in Java 8

String

StringBuilder

StringBuffer

Both B and C

HelloWorld

Hello World

Hello

World

str.length

str.length()

str.size()

len(str)

String is immutable, StringBuilder is mutable

String is mutable, StringBuilder is immutable

Both are immutable

Both are mutable

equalsIgnoreCase()

compareToIgnoreCase()

Both A and B

equals()

List

Set

Collection

Map

Set

List

Map

Queue

ArrayList is faster for random access, LinkedList for insertion/deletion

LinkedList is faster for random access

ArrayList is faster for insertion/deletion

No difference

ArrayList

HashSet

TreeSet

LinkedList

HashMap is unsorted, TreeMap is sorted

TreeMap is unsorted, HashMap is sorted

Both are sorted

Both are unsorted

List

Set

Map

Queue

try

catch

finally

All of these

Exception

Throwable

Error

RuntimeException

Checked exceptions are checked at compile time, unchecked at runtime

Unchecked exceptions are checked at compile time

Both are checked at compile time

Both are checked at runtime

throw

throws

try

catch

To execute code regardless of exception

To catch exceptions

To throw exceptions

To handle exceptions

NullPointerException

ArrayIndexOutOfBoundsException

IOException

ArithmeticException

synchronized

volatile

atomic

lock

Extend Thread class

Implement Runnable interface

Both A and B

Use ThreadFactory

sleep() is for Thread, wait() is for Object

sleep() releases lock, wait() doesn't

Both release lock

Both are for Thread

run()

start()

execute()

begin()

To ensure visibility of changes to variables across threads

To make a variable read-only

To declare a static variable

To initialize a variable

Two or more threads are waiting forever for each other to release resources

A thread is waiting for its own lock

Threads are executing simultaneously

Threads are paused

java.io

java.nio

java.file

Both A and B

FileReader

BufferedReader

Both A and B

FileInputStream

FileWriter

BufferedWriter

Both A and B

FileOutputStream

FileReader reads character data, FileInputStream reads byte data

FileReader reads byte data, FileInputStream reads character data

Both read character data

Both read byte data

readLine()

read()

getLine()

nextLine()

To automatically close resources

To handle exceptions

To define resources

To open files

Java 7

Java 8

Java 9

Java 11

(parameters) -> expression

(parameters) => expression

parameters -> expression

function(parameters) -> expression

An interface with a single abstract method

An interface with multiple abstract methods

An interface with no methods

An interface with default methods

To perform functional operations on collections

To create new collections

To iterate over arrays

To write to files

map() returns a stream, flatMap() flattens nested streams

flatMap() returns a stream, map() flattens nested streams

Both flatten nested streams

Both return streams

@FunctionalInterface

@Functional

@Interface

@Lambda

Java Database Connectivity

Java Database Connection

Java Data Base Connection

Java Database Controller

Class.forName()

DriverManager.getDriver()

Driver.load()

JDBC.load()

Statement

PreparedStatement

CallableStatement

All of these

PreparedStatement prevents SQL injection

Statement prevents SQL injection

Both prevent SQL injection

Neither prevents SQL injection

executeQuery()

executeUpdate()

execute()

runQuery()

To store and navigate query results

To execute queries

To connect to databases

To close connections

To provide compile-time type safety

To improve performance

To reduce code

To create objects

class MyClass<T>

class MyClass[T]

class MyClass(T)

generic class MyClass<T>

A type parameter that extends a specific class

A type parameter with no bounds

A type parameter for primitive types

A type parameter for arrays

An unknown type represented by ?

A specific type

A primitive type

A void type

No, due to type erasure

Yes, using T[]

Yes, using generic arrays

Only with ArrayList

Removing generic type information at compile time

Removing class information

Removing method information

Removing variable information

To provide metadata about the code

To execute code

To create objects

To declare variables

@Override

@OverrideMethod

@Overrides

@Super

@Deprecated

@DeprecatedMethod

@Obsolete

@Old

An annotation with no elements

An annotation with one element

An annotation with multiple elements

An annotation that is not used

To mark an interface with a single abstract method

To mark a class as functional

To mark a method as functional

To create lambda expressions

An annotation applied to other annotations

An annotation applied to classes

An annotation applied to methods

An annotation applied to fields

Java Virtual Machine

Java Variable Manager

Java Version Manager

Java Visual Machine

Automatic memory management

Manual memory management

Memory allocation

Memory deallocation

finalize()

dispose()

destroy()

clean()

Memory area for objects

Memory area for stack frames

Memory area for method area

Memory area for native methods

Memory area for method frames and local variables

Memory area for objects

Memory area for classes

Memory area for threads

To create objects

To create arrays

To allocate memory

All of these

Inspecting and modifying classes at runtime

Creating objects at runtime

Executing methods at runtime

All of these

A group of related packages

A single class

A method

An interface

Java 8

Java 9

Java 10

Java 11

Local variable type inference

Variable declaration

Constant declaration

Method declaration

A class with restricted subclasses

A class that cannot be instantiated

A class with private methods

A class with no methods

A transparent data carrier class

A database record

A file record

A method record

JDK includes development tools, JRE only runs programs

JRE includes development tools, JDK only runs programs

Both include development tools

Both only run programs

Integer

Int

int

IntWrapper

3

1

0

2

continue

break

return

goto

final is for constants, finally is for exception handling, finalize is for garbage collection

All are the same

final is for methods, finally is for variables

finalize is for inheritance

0

null

undefined

garbage value

toUpperCase()

toUpper()

upperCase()

toUppercase()

LinkedHashSet maintains insertion order, HashSet doesn't

HashSet maintains insertion order, LinkedHashSet doesn't

Both maintain insertion order

Neither maintains insertion order

Yes

No

Only in Java 8

Only in Java 11

Synchronized method locks the entire method, synchronized block locks only specified code

Synchronized block locks the entire method

Both are the same

Neither provides synchronization

To allow object serialization

To allow object cloning

To allow object comparison

To allow object creation

An operation that produces a result

An operation that transforms data

An operation that filters data

An operation that sorts data

createStatement()

getStatement()

prepareStatement()

getPreparedStatement()

To set upper bound for type parameter

To set lower bound for type parameter

To define an interface

To create a class

To suppress compiler warnings

To suppress runtime errors

To suppress exceptions

To suppress methods

Heap stores objects, stack stores method frames and local variables

Stack stores objects, heap stores method frames

Both store objects

Neither stores objects