Untitled Quiz

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Questions and Answers

How should the rear pointer be updated when inserting an element in a queue?

rear=(rear%1)+MAX_SIZE

rear=rear%(MAX_SIZE+1)

rear=rear+(1%MAX_SIZE)

rear=(rear+1)%MAX_SIZE (correct)

What will be the output of the given Java program that manipulates a LinkedList?

2 5 8

2 1 8 (correct)

2 8 5

8 5 1

Is PriorityQueue thread safe?

True (correct)

False

Which method is used to clear a specified bit in a data structure?

clear() Signup and view all the answers

Which method of the Date class checks if one date is before another date?

before() Signup and view all the answers

What happens when two threads try to access the same ArrayList simultaneously?

ConcurrentModificationException is thrown. Signup and view all the answers

What will be the output when adding elements to an ArrayList as shown in the Java program?

2 Signup and view all the answers

Which data structure is typically used in Breadth First Traversal of a graph?

Queue Signup and view all the answers

What does a package in Java mainly consist of?

A collection of classes and interfaces Signup and view all the answers

Which keyword is essential for defining a package in Java?

package Signup and view all the answers

What option describes the main purpose of a package in Java?

To organize classes and interfaces Signup and view all the answers

How would you properly import all classes from a specific package in Java?

import packageName.*; Signup and view all the answers

Which is the automatically imported package in every Java program?

java.lang Signup and view all the answers

Which of the following packages contains the Scanner class used for input?

java.util Signup and view all the answers

What is indicated by the fully qualified name of a class in Java?

Class name and package name together Signup and view all the answers

Is it possible for two different packages in Java to have classes with the same name?

Yes, packages isolate classes Signup and view all the answers

How can you use a class from another package without importing it?

Use the fully qualified name of the class Signup and view all the answers

What is the primary purpose of the java.sql package?

Handling database operations Signup and view all the answers

Can a package include private classes?

Yes Signup and view all the answers

What does the CLASSPATH variable in Java specify?

Both B and C Signup and view all the answers

Which package in Java contains classes specifically for networking?

java.net Signup and view all the answers

What type of classes are contained within the java.util package?

Utility classes like Scanner and ArrayList Signup and view all the answers

Which method is used to initiate a thread in Java?

start() Signup and view all the answers

Which interface must be implemented to create a thread in Java?

Runnable Signup and view all the answers

What will occur if the run() method is invoked directly instead of the start() method?

The code will run in the current thread Signup and view all the answers

What is the primary function of the synchronized keyword in Java?

Prevents thread interference and memory consistency errors Signup and view all the answers

When a thread goes to sleep using Thread.sleep(), what happens?

The thread releases CPU but holds any locks it has Signup and view all the answers

Which method should be used to make one thread wait for another to complete?

join() Signup and view all the answers

Which method can be called to check if a thread is currently alive?

isAlive() Signup and view all the answers

What is the role of the yield() method in Java threads?

It pauses the thread to allow other threads of the same priority to execute Signup and view all the answers

What exception is raised if the sleep() method is interrupted?

InterruptedException Signup and view all the answers

How does the notifyAll() method function in thread management?

Wakes up all threads waiting on the object's monitor Signup and view all the answers

What will be the output of the Java program that adds elements to a TreeSet and prints it?

[1, 3, 4, 8, 9] Signup and view all the answers

How do you synchronize access to a HashMap?

Collections.synchronizedMap(new HashMap()); Signup and view all the answers

What is the relation between HashSet and HashMap?

HashSet internally implements HashMap. Signup and view all the answers

Which method of the ArrayList class retrieves the current size of the list?

size() Signup and view all the answers

What will be the result of using max() method incorrectly, such as max(Comparator comp)?

It throws a compilation error. Signup and view all the answers

Which iterator is specifically designed to work only with List collections?

ListIterator Signup and view all the answers

What will the output be if we add multiple null entries in a TreeMap?

{1=null, 2=null, 3=null, 4=null, 5=null} Signup and view all the answers

Which method is used to remove duplicates from a List using HashSet?

new HashSet(duplicateList); Signup and view all the answers

How can we make all elements of a collection equal to a specified value?

fill() Signup and view all the answers

Which method is not implemented in HashSet to retrieve an object?

get() Signup and view all the answers

Which Java collection class has a fixed size when initialized using Arrays.asList()?

Collections type Lists Signup and view all the answers

What happens when invoking clear() on a Hashtable?

All elements are removed Signup and view all the answers

Which of the following statements about properties object is false?

It uses a linear data structure Signup and view all the answers

What is the primary purpose of the Comparator interface in the Java Collections Framework?

It defines a comparison function for ordering elements Signup and view all the answers

Which of these methods can be used to convert an object into a List?

singletonList() Signup and view all the answers

Which interface in the Java Collections Framework represents a collection of elements stored in sorted order?

SortedSet Signup and view all the answers

What is the primary difference between a HashSet and a LinkedHashSet?

LinkedHashSet maintains insertion order; HashSet does not Signup and view all the answers

Which class typically implements a Deque in the Java Collections Framework?

ArrayDeque Signup and view all the answers

What method is used to remove all elements from a collection in the Java Collections Framework?

clear() Signup and view all the answers

Which class is used to implement a Map interface in the Java Collections Framework?

LinkedHashMap Signup and view all the answers

What will be the output of a program that uses the Collections.sort() method on a list with unsorted integers?

The list will be sorted in ascending order Signup and view all the answers

What happens when two threads simultaneously modify a TreeSet?

A ConcurrentModificationException is thrown Signup and view all the answers

Which of the following interfaces represents a last-in, first-out (LIFO) stack of elements?

Stack Signup and view all the answers

What is the purpose of the toArray() method in the Java Collections Framework?

To convert a collection to an array Signup and view all the answers

Which of these methods can be used to obtain a synchronized (thread-safe) version of a collection?

Collections.synchronizedCollection() Signup and view all the answers

Which class is typically used to implement a Set in the Java Collections Framework?

HashSet Signup and view all the answers

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

The capacity of the ArrayList is decreased to its size Signup and view all the answers

Study Notes

Question 1

The Collections Framework provides a unified architecture for representing and manipulating collections.

Question 2

The List interface in the Java Collections Framework represents an ordered collection that can contain duplicate values.

Question 3

The primary difference between a List and a Set is that a List allows duplicate elements, while a Set does not.

Question 4

The ArrayList class is typically used to implement a List in the Java Collections Framework.

Question 5

The Deque interface extends the List interface to provide more efficient insertions and deletions in the middle of the list.

Question 6

The Map interface in the Java Collections Framework is used to store key-value pairs.

Question 7

The HashMap class is typically used to implement a Map in the Java Collections Framework.

Question 8

The TreeMap allows duplicate keys, while a HashMap does not.

Question 9

The Set interface represents a collection of unique elements with no duplicates.

Question 10

The HashSet class is typically used to implement a Set in the Java Collections Framework.

Question 11

LinkedHashSet maintains insertion order, while HashSet does not.

Question 12

The Collection interface represents a collection of elements with no specific order.

Question 13

A Queue represents a single-ended queue, while a Deque represents a double-ended queue.

Question 14

The ArrayDeque class is typically used to implement a Deque in the Java Collections Framework.

Question 15

The Collections class allows you to create a synchronized (thread-safe) collection.

Question 16

The SortedSet interface extends the Set interface and represents a collection of elements stored in a sorted order.

Question 17

The Comparator interface in Java provides methods for comparing objects to enable ordering.

Question 18

The TreeSet class implements the SortedSet interface.

Question 19

The Stack interface represents a last-in, first-out (LIFO) stack of elements.

Question 20

A Stack uses LIFO order, while a Queue uses FIFO order.

Question 21

The add() method is used to add an element to a collection in the Java Collections Framework.

Question 22

The toArray() method converts a collection to an array.

Question 23

The Collections class provides methods to manipulate the size of a list and its elements.

Question 24

The Iterator interface provides a way to iterate over a collection's elements.

Question 25

The clear() method removes all elements from a collection.

Question 26

The Map.Entry interface represents a key-value pair in a map.

Question 27

The Collections.synchronizedCollection() method obtains a synchronized or thread-safe version of a collection.

Question 28

HashSet does not maintain insertion order; LinkedHashSet does.

Question 29

The Collections.synchronizedMap() method is used to make a synchronized map from an existing map.

Question 30

The Collections.reverse() method reverses the order of elements in a list.

Question 31

The ensureCapacity() method increases the capacity of an ArrayList object.

Question 32

The output of the provided Java code snippet is [D, A, B, C].

Question 33

A Collection in Java is a group of objects.

Question 34

The singletonList() method converts an object into a List.

Question 35

The output of the provided Java code snippet is 2.

Question 36

The premise of equality for IdentityHashMap is reference equality.

Question 37

The EMPTY_LIST is a static variable defined in Collections.

Question 38

The addElement() method is used to add elements to a Vector at specific locations.

Question 39

The output of the provided Java code is 1582.

Question 40

Stack is LIFO; Queue is FIFO.

Question 41

The output of the provided Java code is {3, 4}.

Question 42

Front pointer points to the first element; rear pointer points to the last element

Question 43

BlockingQueue is a sub-interface of Queue.

Question 44

trimToSize() method is used to reduce the capacity of an ArrayList object.

Question 45

Collections.sort(listObj) is used to sort elements of an ArrayList.

Question 46

The java.util package contains all collection classes.

Question 47

The keySet() method is used to obtain a set of all keys in a map.

Question 48

Remote class methods are checkIP(), addLocation(), and AddServer().

Question 49

The get() method of Map class is used to obtain an element with the specified key.

Question 50

The elementCount data member of Vector stores the number of elements.

Question 51

The output of the provided Java code snippet is {A=1, B=2, C=3}.

Question 52

The java code sample will output the current time and date.

Question 53

The worst case time complexity of accessing an element in ArrayList is O(1).

Question 54

The ArrayList class implements a dynamic array.

Question 55

The enqueue() and dequeue() methods are used to insert and delete items from a queue.

Question 56

The LinkedList class implements all the standard functions on list data structure.

Question 57

ConcurrentModificationException is thrown if two threads modify a TreeSet simultaneously.

Question 58

The output of the provided Java code snippet is Test 10 and Test 10.

Question 59

The Set interface and HashSet class do not maintain order.

Question 60

The Enumeration interface is a legacy interface.

Question 61

The output of the provided Java code snippet is false.

Question 62

The key is hashed multiple times until the correct bucket is found.

Question 63

The Collection interface is a basic interface that other interfaces inherit.

Question 64

The previousIndex() method of ListIterator obtains the index of the previous element.

Question 65

The output of the provided Java code snippet is [A, D, B, C].

Question 66

The output of the provided Java code snippet is 12345.

Question 67

The length() method calculates the number of bits required to hold a BitSet object.

Question 68

RemoteException is a possible exception thrown by a remote method.

Question 69

BitSet objects have an architecture similar to arrays.

Question 70

The sort() method in the Array class sorts the array or its subset.

Question 71

The output of the program is {A=3, B=2, C=8}.

Question 72

The Enumeration interface is implemented by Hashtable and Dictionary classes.

Question 73

The output of the following Java code snippet is 12345.

Question 74

LinkedHashSet maintains insertion order and ensures uniqueness of elements.

Question 75

The output of the program is false.

Question 76

The output of the program is {A=1, B=2, C=3}.

Question 77

Map class objects use keys to store values.

Question 78

ArrayList and Vector can be used to create dynamic arrays.

Question 79

The output of the Java program is 1852.

Question 80

The output of the Java code snippet is [5, 8, 2, 3, 2].

Question 81

The output of the provided Java code snippet is 2.

Question 82

The shuffle() method randomizes elements.

Question 83

The toArray() method is used to obtain a static array from ArrayList objects.

Question 84

The put() method inserts a value and its key into a Map.

Question 85

The clear() method removes all entries from a Map.

Question 86

The output of the following Java program is "EMPTY".

Question 87

The output depends on the program to be run.

Question 88

If a key object already exists in a HashMap, the new object replaces the existing key-value pair.

Question 89

List and Collection handle sequences.

Question 90

Collections.synchronizedMap() is used for externally synchronizing HashMap.

Question 91

Set does have the contains(Object o) method.

Question 92

HashMap is not a concrete class; HashSet is a concrete class built upon HashMap.

Question 93

The iterator() method can obtain an iterator to the set's start.

Question 94

max(Comparator comp) is an incorrect method for max in Java.

Question 95

The iterator() method is used to obtain an iterator to the start of a Collection.

Question 96

The output of the program is [1, 3, 4, 8, 9].

Question 97

The output of the program is 81432

Question 98

The output of the program is 0

Question 99

The getProperty() method retrieves elements from a Properties object.

Question 100

Set has a contains(Object o) method.

Question 101

HashSet is implemented on top of HashMap.

Question 102

The return type of the hasNext() method of an iterator is Boolean.

Question 103

The method iterator() is used to obtain an iterator to the start of a Collection.

Question 104

The output of the following Java program is [1, 3, 4, 8, 9].

Question 105

The output of the program is 58881.

Question 106

The output of the following Java code is 0.

Question 107

The getProperty() method is used to retrieve elements in the Properties object.

Question 108

The put() method is used to add elements to a Map.

Question 109

HashSet<String> listToSet = new HashSet<>(duplicateList); This line of code converts a List into a Set that removes duplicates.

Question 110

The ListIterator can be used only with a List.

Question 111

HashMap is not an ordered collection.

Question 112

Arrays.asList() creates an unmodifiable List, limiting its capacity and preventing the addition or removal of elements.

Question 113

dequeue() removes and returns the next item, whereas peek() only returns, but does not remove, the next item.

Question 114

The size() method gets the current size of an ArrayList.

Question 115

Stack, Hashtable, and Vector are legacy classes.

Question 116

The initial capacity of HashSet is 16, and the load factor is 0.75.

Question 117

The output of the Java program will be 2851.

Question 118

The output will be 1582.

Question 119

HashSet does not have a get(Object o) method.

Question 120

LinkedList implements a linked list data structure.

Question 121

The clear() method deletes all elements from the collection.

Question 122

Collections.emptySet() returns an immutable set.

Question 123

The output of the code will be [1=null, 2=null, 3=null, 4=null, 5=null].

Question 124

The output is 6.

Question 125

The Map object manages key-value associations.

Question 126

The output of the program is 1582.

Question 127

The get() method can be used to retrieve an element in a list.

Question 128

The remove() method, or using an iterator, is used to eliminate an object from an ArrayList.

Question 129

The output of the program is 2.

Question 130

The output of the program will be 54321.

Question 131

The next() method moves to the next element.

Question 132

This question is missing from the data.

Question 133

This question is missing from the data.

Question 134

The set() method changes an element in a LinkedList.

Question 135

The output of the Java program is [A, B, C].

Question 136

The output of the java code is [3,2,6,8].

Question 137

The output of the java code is {B=2, C=8}

Question 138

HashSet is a class that implements Set.

Question 139

SortedList is not a Java collection interface.

Question 140

The fill() method sets all elements of a collection to a given value.

Question 141

The Collection interface declares fundamental methods that are commonly used across collections.

Question 142

SortedSet is an interface, and TreeSet is a class that implements it.

Question 143

Map is not an interface for Collection.

Question 144

The output of the program will be 285 1.

Question 145

The output of this Java code will be a randomized order of the numbers (2, 1, 8, 5).

Question 146

fill() method in Java's collections framework sets all elements of a list to a given value.

Question 147

removeLast() is used to delete the last element of a LinkedList.

Question 148

The add() method is not used in this context, but addFirst() is used to add to the front of a LinkedList.

Question 149

The output of the java program is [AB, BC, CD].

Question 150

Vector does not implement the Map interface.

Question 151

HashMap, and Hashtable are Map implementations.

Question 152

The get() method is used to obtain an element from BitSet

Question 153

IllegalStateException can occur from a remove() method in a collection.

Question 154

The add() method is used to add elements into a HashSet.

Question 155

The output is 2.

Question 156

The output is ["A", "D"].

Question 157

Set interface requires unique elements

Question 158

size() of ArrayList returns number of elements, and length() is not a valid method for ArrayList.

Question 159

The rear pointer is updated using the formula rear=(rear+1)%MAX_SIZE to implement a circular queue.

Question 160

The output of the program is 851.

Question 161-166

These questions relate to the functionality of the Date class, and Set and Map interfaces.

Question 167

Maps isn't a Java collection framework interface.

Question 168-171

These questions deal with Java code packages.

Question 172-176

These questions involve Java packages and their properties

Question 177

The java.io package contains classes for handling input and output operations.

Question 178

The syntax to create a package in Java is package packageName;.

Question 179

Yes, two packages can have classes with the same name.

Question 180

java.graphics is not part of the Java standard library.

Question 181

Use the fully qualified class name to access a class in another package.

Question 182-186

These questions cover the purpose and functionalities of various Java packages.

Question 187-191

These questions involve Java threads and their properties.

Question 192-201

These involve information about various Java threading concepts like wait, notify, join, sleep.

Question 202-206

These questions deal with thread pools and concepts of concurrency.