Latest java Interview Questions and Answers 2024 for Freshers and Experienced

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If you're looking for current Java interview questions and answers, you've come to the right place! This Latest 2024 Question List will provide you with a comprehensive list of trending Java interview questions and answers asked in Top Companies interview round.

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#	Question	Options	Answer
201	Which of these keywords are used to define an abstract class?	abst abstract Abstract abstract class	abstract
202	Which of these is not abstract?	Thread AbstractList List None of the Mentioned	Thread
203	If a class inheriting an abstract class does not define all of its function then it will be known as?	Abstract A simple class Static class None of the mentioned	Abstract
204	Which of these is not a correct statement?	Every class containing abstract method must be declared abstract Abstract class defines only the structure of the class not its implementation Abstract class can be initiated by new operator Abstract class can be inherited	Abstract class can be initiated by new operator
205	Which of these packages contains abstract keyword?	java.lang java.util java.io java.system	java.lang
206	Which of these class is superclass of String and StringBuffer class?	java.util java.lang ArrayList None of the mentioned	java.lang
207	Which of these operators can be used to concatenate two or more String objects?	+ += & \|\|	+
208	Which of this method of class String is used to obtain a length of String object?	get() Sizeof() lengthof() length()	length()
209	Which of these constructors is used to create an empty String object?	String() String(void) String(0) None of the mentioned	String()
210	Which of these is an incorrect statement?	String objects are immutable, they cannot be changed String object can point to some other reference of String variable StringBuffer class is used to store string in a buffer for later use None of the mentioned	StringBuffer class is used to store string in a buffer for later use
211	Which of this method of class String is used to extract a substring from a String object?	substring() Substring() SubString() None of the mentioned	substring()
212	Which of these method of class String is used to remove leading and trailing whitespaces?	startsWith() trim() Trim() doTrim()	trim()
213	What is the value returned by function compareTo() if the invoking string is greater than the string compared?	zero value less than zero value greater than zero none of the mentioned	value greater than zero
214	Which of the following statement is correct?	replace() method replaces all occurrences of one character in invoking string with another character replace() method replaces only first occurrences of a character in invoking string with another character replace() method replaces all the characters in invoking string with another character replace() replace() method replaces last occurrence of a character in invoking string with another character	replace() method replaces all occurrences of one character in invoking string with another character
215	Which of these method of class String is used to compare two String objects for their equality?	equals() Equals() isequal() Isequal()	equals()
216	Which of these methods is used to compare a specific region inside a string with another specific region in another string?	regionMatch() match() RegionMatches() regionMatches()	regionMatches()
217	Which of these methods of class String is used to check whether a given object starts with a particular string literal?	startsWith() endsWith() Starts() ends()	startsWith()
218	What is the value returned by function compareTo() if the invoking string is less than the string compared?	zero value less than zero value greater than zero none of the mentioned	value less than zero
219	Which of these data type value is returned by equals() method of String class?	char int boolean all of the mentioned	boolean
220	Which of these class is used to create an object whose character sequence is mutable?	String() StringBuffer() String() & StringBuffer() None of the mentioned	StringBuffer()
221	Which of this method of class StringBuffer is used to concatenate the string representation to the end of invoking string?	concat() append() join() concatenate()	append()
222	Which of these method of class StringBuffer is used to find the length of current character sequence?	length() Length() capacity() Capacity()	length()
223	Which of the following statement is correct?	reverse() method reverses all characters reverseall() method reverses all characters replace() method replaces first occurrence of a character in invoking string with another character replace() method replaces last occurrence of a character in invoking string with another character	reverse() method reverses all characters
224	Which of these methods of class StringBuffer is used to extract a substring from a String object?	substring() Substring() SubString() None of the mentioned	substring()
225	Which of this method of class StringBuffer is used to reverse sequence of characters?	reverse() reverseall() Reverse() reverseAll()	reverse()
226	Which of this method of class StringBuffer is used to get the length of the sequence of characters?	length() capacity() Length() Capacity()	length()
227	Which of these is a process of writing the state of an object to a byte stream?	Serialization Externalization File Filtering All of the mentioned	Serialization
228	Which of these process occur automatically by the java runtime system?	Serialization Garbage collection File Filtering All of the mentioned	Serialization
229	Which of these is an interface for control over serialization and deserialization?	Serializable Externalization FileFilter ObjectInput	Externalization
230	Which of these interface extends DataOutput interface?	Serializable Externalization ObjectOutput ObjectInput	ObjectOutput
231	Which of these is a method of ObjectOutput interface used to finalize the output state so that any buffers are cleared?	clear() flush() fflush() close()	flush()
232	Which of these is method of ObjectOutput interface used to write the object to input or output stream as required?	write() Write() StreamWrite() writeObject()	writeObject()
233	Which of these is a process of extracting/removing the state of an object from a stream?	Serialization Externalization File Filtering Deserialization	Deserialization
234	Which of these process occur automatically by java run time system?	Serialization Memory allocation Deserialization All of the mentioned	All of the mentioned
235	Which of these interface extends DataInput interface?	Serializable Externalization ObjectOutput ObjectInput	ObjectInput
236	Which of these class extend InputStream class?	ObjectStream ObjectInputStream ObjectOutput ObjectInput	ObjectInputStream
237	How an object can become serializable?	If a class implements java.io.Serializable class If a class or any superclass implements java.io.Serializable interface Any object is serializable No object is serializable	If a class or any superclass implements java.io.Serializable interface
238	What is serialization?	Turning object in memory into stream of bytes Turning stream of bytes into an object in memory Turning object in memory into stream of bits Turning stream of bits into an object in memory	Turning object in memory into stream of bytes
239	What is deserialization?	Turning object in memory into stream of bytes Turning stream of bytes into an object in memory Turning object in memory into stream of bits Turning stream of bits into an object in memory	Turning stream of bytes into an object in memory
240	How many methods Serializable has?	1 2 3 0	0
241	What type of members are not serialized?	Private Protected Static Throwable	Static
242	If member does not implement serialization, which exception would be thrown?	RuntimeException SerializableException NotSerializableException UnSerializedException	NotSerializableException
243	Which of the following methods is used to avoid serialization of new class whose super class already implements Serialization?	writeObject() readWriteObject() writeReadObject() unSerializaedObject()	writeObject()
244	Which of the following methods is not used while Serialization and DeSerialization?	readObject() readExternal() readWriteObject() writeObject()	readWriteObject()
245	Which of these package contains classes and interfaces for networking?	java.io java.util java.net java.network	java.net
246	Which of these is a protocol for breaking and sending packets to an address across a network?	TCP/IP DNS Socket Proxy Server	TCP/IP
247	How many ports of TCP/IP are reserved for specific protocols?	10 1024 2048 512	1024
248	How many bits are in a single IP address?	8 16 32 64	32
249	Which of these is a full form of DNS?	Data Network Service Data Name Service Domain Network Service Domain Name Service	Domain Name Service
250	Which of these class is used to encapsulate IP address and DNS?	DatagramPacket URL InetAddress ContentHandler	InetAddress
251	Which of these interface abstractes the output of messages from httpd?	LogMessage LogResponse Httpdserver httpdResponse	LogMessage
252	Which of these class is used to create servers that listen for either local or remote client programs?	httpServer ServerSockets MimeHeader HttpResponse	ServerSockets
253	Which of these is a standard for communicating multimedia content over email?	http https Mime httpd	Mime
254	Which of these methods is used to make raw MIME formatted string?	parse() toString() getString() parseString()	parse()
255	Which of these class is used for operating on request from the client to the server?	http httpDecoder httpConnection httpd	httpd
256	Which of these method of MimeHeader is used to return the string equivalent of the values stores on MimeHeader?	string() toString() convertString() getString()	toString()
257	Which of these is an instance variable of class httpd?	port cache log All of the mentioned	All of the mentioned
258	Which of these methods of httpd class is used to read data from the stream?	getDta() GetResponse() getStream() getRawRequest()	getRawRequest()
259	Which of these method of httpd class is used to get report on each hit to HTTP server?	log() logEntry() logHttpd() logResponse()	logEntry()
260	Which of these methods are used to find a URL from the cache of httpd?	findfromCache() findFromCache() serveFromCache() getFromCache()	serveFromCache()
261	Which of these variables stores the number of hits that are successfully served out of cache?	hits hitstocache hits_to_cache hits.to.cache	hits.to.cache
262	Which of these method of httpd class is used to write UrlCacheEntry object into local disk?	writeDiskCache() writetoDisk() writeCache() writeDiskEntry()	writeDiskCache()
263	Which of these method is used to start a server thread?	run() start() runThread() startThread()	run()
264	Which of these method is called when http daemon is acting like a normal web server?	Handle() HandleGet() handleGet() Handleget()	handleGet()
265	Which of these standard collection classes implements a dynamic array?	AbstractList LinkedList ArrayList AbstractSet	ArrayList
266	Which of these class can generate an array which can increase and decrease in size automatically?	ArrayList() DynamicList() LinkedList() MallocList()	ArrayList()
267	Which of these method of ArrayList class is used to obtain present size of an object?	size() length() index() capacity()	size()
268	Which of these methods can be used to obtain a static array from an ArrayList object?	Array() convertArray() toArray() convertoArray()	toArray()
269	Which of these method is used to reduce the capacity of an ArrayList object?	trim() trimSize() trimTosize() trimToSize()	trimToSize()
270	Map implements collection interface?	True False No idea All of the above	False
271	Which of the below does not implement Map interface?	HashMap Hashtable EnumMap Vector	Vector
272	What is the premise of equality for IdentityHashMap?	Reference equality Name equality Hashcode equality Length equality	Reference equality
273	What happens if we put a key object in a HashMap which exists?	The new object replaces the older object The new object is discarded The old object is removed from the map It throws an exception as the key already exists in the map	The new object replaces the older object
274	If two threads access the same hashmap at the same time, what would happen?	ConcurrentModificationException NullPointerException ClassNotFoundException RuntimeException	ConcurrentModificationException
275	If large number of items are stored in hash bucket, what happens to the internal structure?	The bucket will switch from LinkedList to BalancedTree The bucket will increase its size by a factor of load size defined The LinkedList will be replaced by another hashmap Any further addition throws Overflow exception	The bucket will switch from LinkedList to BalancedTree
276	How can we remove an object from ArrayList?	remove() method using Iterator remove() method and using Iterator delete() method	remove() method and using Iterator
277	How to sort elements of ArrayList?	Collection.sort(listObj); Collections.sort(listObj); listObj.sort(); Sorter.sortAsc(listObj);	Collections.sort(listObj);
278	When two threads access the same ArrayList object what is the outcome of the program?	Both are able to access the object ConcurrentModificationException is thrown One thread is able to access the object and second thread gets Null Pointer exception One thread is able to access the object and second thread will wait till control is passed to the second one	ConcurrentModificationException is thrown
279	How is Arrays.asList() different than the standard way of initialising List?	Both are same Arrays.asList() throws compilation error Arrays.asList() returns a fixed length list and doesn’t allow to add or remove elements We cannot access the list returned using Arrays.asList()	Arrays.asList() returns a fixed length list and doesn’t allow to add or remove elements
280	What is the difference between length() and size() of ArrayList?	length() and size() return the same value length() is not defined in ArrayList size() is not defined in ArrayList length() returns the capacity of ArrayList and size() returns the actual number of elements stored in the list	length() returns the capacity of ArrayList and size() returns the actual number of elements stored in the list
281	Which class provides thread safe implementation of List?	ArrayList CopyOnWriteArrayList HashList List	CopyOnWriteArrayList
282	Which of the below is not an implementation of List interface?	RoleUnresolvedList Stack AttibuteList SessionList	SessionList
283	What does Collections.emptySet() return?	Immutable Set Mutable Set The type of Set depends on the parameter passed to the emptySet() method Null object	Immutable Set
284	What is the relation between hashset and hashmap?	HashSet internally implements HashMap HashMap internally implements HashSet HashMap is the interface; HashSet is the concrete class HashSet is the interface; HashMap is the concrete class	HashSet internally implements HashMap
285	What is the difference between TreeSet and SortedSet?	TreeSet is more efficient than SortedSet SortedSet is more efficient than TreeSet TreeSet is an interface; SortedSet is a concrete class SortedSet is an interface; TreeSet is a concrete class	SortedSet is an interface; TreeSet is a concrete class
286	What happens if two threads simultaneously modify TreeSet?	ConcurrentModificationException is thrown Both threads can perform action successfully FailFastException is thrown IteratorModificationException is thrown	ConcurrentModificationException is thrown
287	What is the unique feature of LinkedHashSet?	It is not a valid class It maintains the insertion order and guarantees uniqueness It provides a way to store key values with uniqueness The elements in the collection are linked to each other	It maintains the insertion order and guarantees uniqueness
288	Which of these standard collection classes implements a linked list data structure?	AbstractList LinkedList HashSet AbstractSet	LinkedList
289	Which of these classes implements Set interface?	ArrayList HashSet LinkedList DynamicList	HashSet
290	Which of these method is used to add an element to the start of a LinkedList object?	add() first() AddFirst() addFirst()	addFirst()
291	Which of these method of HashSet class is used to add elements to its object?	add() Add() addFirst() insert()	add()
292	Which of these methods can be used to delete the last element in a LinkedList object?	remove() delete() removeLast() deleteLast()	removeLast()
293	Which of this method is used to change an element in a LinkedList Object?	change() set() redo() add()	set()
294	Which of these object stores association between keys and values?	Hash table Map Array String	Map
295	Which of these classes provide implementation of map interface?	ArrayList HashMap LinkedList DynamicList	HashMap
296	Which of these method is used to remove all keys/values pair from the invoking map?	delete() remove() clear() removeAll()	remove()
297	Which of these method Map class is used to obtain an element in the map having specified key?	search() get() set() look()	get()
298	Which of these methods can be used to obtain set of all keys in a map?	getAll() getKeys() keyall() keySet()	keySet()
299	Which of these method is used add an element and corresponding key to a map?	put() set() redo() add()	put()
300	Which of these class object can be used to form a dynamic array?	ArrayList Map Vector ArrayList & Vector	ArrayList & Vector

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