Quiz | Croma Campus

Which of these is an interface in Java?

Runnable
RunnableThread
SerializableThread
SerializableRun

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What is the use of the 'this' keyword in Java?

To refer to the current object
To refer to the parent class object
To refer to the child class object
To refer to the object of the same class

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Which method is used to get the current thread in Java?

currentThread()
activeThread()
current()
active()

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Which of the following cannot be stored in a Collection?

Objects
Primitive data types
Arrays
User-defined classes

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Which method is used to add elements to a collection?

add()
append()
insert()
push()

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Which of these is not a valid identifier in Java?

_abc
$abc
abc123
123abc

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Which of these methods can be used to check if a key exists in a Map?

contains()
hasKey()
containsKey()
has()

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Which of these classes are synchronized?

ArrayList
Vector
HashMap
HashSet

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Which of these is a valid declaration of a char?

char ch = 'ab';
char ch = 'a';
char ch = 'a'';
char ch = a;

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Which keyword is used to prevent inheritance of a class in Java?

final
finally
finalize
static

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Which of these keywords is used to define an abstract class in Java?

abstract
final
static
volatile

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What is the default value of byte variable in Java?

0
0
null
undefined

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Which of the following is not a Java feature?

Dynamic
Architecture Neutral
Use of pointers
Object-oriented

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Which method in Thread class is used to pause the execution of a thread for a specific time?

wait()
sleep()
pause()
stop()

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Which package is automatically imported into every Java program?

java.lang
java.util
java.io
java.net

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Which package contains the Random class in Java?

java.io
java.lang
java.util
java.awt

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Which method of the java.util.ArrayList class is used to obtain the number of elements in an ArrayList object?

size()
count()
length()
getSize()

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Which of these is not a method of the java.lang.String class?

length()
compareTo()
toString()
valueOf()

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Which of these methods is used to obtain an iterator for a collection?

iterator()
iterate()
listIterator()
list()

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Which method is used to start a thread execution in Java?

init()
start()
run()
resume()

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Which of the following is used to find and fix bugs in Java programs?

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Which of these keywords is used to handle exceptions in Java?

try
catch
finally
all of the mentioned

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Which of the following is not a valid declaration of a String?

String s1 = null;
String s2 = "null";
String s3 = (String) "abc";
String s4 = 'abc';

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Which of these is a marker interface?

Runnable
Serializable
Comparable
Cloneable

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Which of the following is true about Java?

Java is a platform-independent language
Java is a language dependent on a platform
Java is a procedure-oriented language
Java does not support OOPS concept

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Which of these classes is used to generate random numbers in Java?

Random
RandomGenerator
RandomGen
Randomize

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Which of the following is not an OOPS concept in Java?

Inheritance
Encapsulation
Polymorphism
Compilation

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Which method is used to compare two strings in Java?

equals()
==
compareTo()
compare()

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Which of these methods is a part of the Abstract class?

main()
abstract()
run()
None of the mentioned

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What is the implicit return type of constructor?

void
int
float
None of the mentioned

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