Java Interview Questions Flashcards
1
Q
What is Java?
A
Let us Java Page 3
https://aws.amazon.com/what-is/java/#:~:text=Java%20is%20a%20widely%2Dused,as%20a%20platform%20in%20itself.
2
Q
Why is Java a popular choice among modern-day software developers?
A
https://aws.amazon.com/what-is/java/#:~:text=Java%20is%20a%20widely%2Dused,as%20a%20platform%20in%20itself.
3
Q
Why is Java Platform Independent?
A
Let us Java Page 4
4
Q
What is the difference between compiler and interpreter?
A
https://www.simplilearn.com/difference-between-compiler-and-interpreter-article#:~:text=A%20compiler%20translates%20the%20entire,potentially%20slowing%20down%20the%20program.
5
Q
Why is Java not a pure object-oriented programming language?
A
https://medium.com/codex/why-is-java-not-a-pure-object-oriented-programming-language-b5ef9b2b291c#:~:text=well%2Ddefined%20interfaces.-,Java%20is%20not%20considered%20a%20pure%20object%2Doriented%20programming%20language,pure%20object%2Doriented%20programming%20language.
6
Q
What are the features of Java?
A
https://www.javatpoint.com/features-of-java
7
Q
Hat do you get in Java Download file?
A
https://www.quora.com/What-do-you-get-in-the-Java-download-file#:~:text=It%20includes%20the%20Java%20Virtual,debugger%2C%20and%20other%20development%20utilities.
8
Q
What is classLoader?
A
https://www.geeksforgeeks.org/classloader-in-java/
9
Q
What are the memory allocations available in Java?
A
https://www.educba.com/types-of-memory-in-java/#:~:text=The%20Java%20virtual%20machine%20memory,area%20and%20Native%20method%20area
10
Q
What is the default value stored in local variables?
A
https://www.tutorialspoint.com/what-is-the-default-value-of-a-local-variable-in-java#:~:text=The%20local%20variables%20do%20not,the%20compiler%20throws%20an%20error.
11
Q
What is association in Java?
A
https://medium.com/edureka/association-in-java-3d0facf63d56#:~:text=What%20is%20the%20Association%3F,and%20many%2Dto%2Dmany.
12
Q
What is Copy Constructor in Java?
A
https://www.javatpoint.com/java-copy-constructor-example
13
Q
What are Marker Interfaces? Can we create own marker interfaces?
A
https://www.baeldung.com/java-marker-interfaces#:~:text=A%20marker%20interface%20is%20an,also%20called%20a%20tagging%20interface.
14
Q
What is Object Cloning?
A
https://www.javatpoint.com/object-cloning
15
Q
What are wrapper classes in Java?
A
https://www.javatpoint.com/wrapper-class-in-java
16
Q
What is singleton class in Java and how to implement it?
A
https://www.geeksforgeeks.org/singleton-class-java/
https://www.javatpoint.com/singleton-design-pattern-in-java
17
Q
What is Package in Java?
A
https://www.javatpoint.com/package
18
Q
Can we implement pointers in Java?
A
https://stackoverflow.com/questions/1750106/how-can-i-use-pointers-in-java
https://www.simplilearn.com/tutorials/java-tutorial/java-interview-questions#GoTop
19
Q
Difference between instance and local variable
A
https://pediaa.com/what-is-the-difference-between-instance-variable-and-local-variable/#:~:text=An%20instance%20variable%20is%20a%20variable%20that%20is%20bound%20to,instance%20variable%20and%20local%20variable.
20
Q
String pool in Java
A
https://www.linkedin.com/pulse/java-strings-string-pool-muhammad-noman?utm_source=share&utm_medium=member_ios&utm_campaign=share_via
https://www.digitalocean.com/community/tutorials/what-is-java-string-pool
https://www.simplilearn.com/tutorials/java-tutorial/java-interview-questions#GoTop
21
Q
What is an Exception?
A
https://docs.oracle.com/javase/tutorial/essential/exceptions/definition.html#:~:text=Definition%3A%20An%20exception%20is%20an,off%20to%20the%20runtime%20system.
Page 453 in Let us Java
22
Q
Final keyword in Java
A
https://www.javatpoint.com/final-keyword
23
Q
Can we declare main[] as Non-static in Java?
A
https://www.tutorialspoint.com/can-we-declare-main-method-as-non-static-in-java
24
Q
Why is main method static in Java?
A
https://www.javatpoint.com/why-main-method-is-always-static-in-java
https://www.scaler.com/topics/why-main-method-is-static-in-java/
25
Garbage collection process
https://www.geeksforgeeks.org/garbage-collection-java/
26
Difference between process and program
https://www.almabetter.com/bytes/articles/difference-between-process-and-program#:~:text=A%20program%20is%20a%20set%20of%20instructions%20written%20in%20a,%2C%20data%2C%20and%20system%20resources.
27
Difference between constructor and method of a class
https://www.geeksforgeeks.org/difference-between-the-constructors-and-methods/
28
Difference between String, StringBuffer and StringBuilder
https://www.digitalocean.com/community/tutorials/string-vs-stringbuffer-vs-stringbuilder#:~:text=String%20is%20immutable%20whereas%20StringBuffer,uses%20StringBuffer%20or%20StringBuilder%20class.
29
Daemon thread in Java?
https://www.geeksforgeeks.org/daemon-thread-java/#:~:text=By%20default%2C%20the%20main%20thread,is%20also%20a%20non%2Ddaemon.
https://www.scaler.com/topics/daemon-thread-in-java/#:~:text=What%20is%20Daemon%20Thread%20in,that%20helps%20the%20user%20thread.
30
What happens if there are multiple main() methods in a class
https://stackoverflow.com/questions/13399836/can-there-exist-two-main-methods-in-a-java-program
31
How does exception propagate in code in Java?
https://www.javatpoint.com/exception-propagation#:~:text=An%20exception%20is%20first%20thrown,bottom%20of%20the%20call%20stack.
32
How do exceptions affect the program if it doesn't handle them?
If you don't deal with an exception once it occurs, the programme will end abruptly and the code after the line where the exception occurred won't run.
Exceptions are runtime errors. Suppose we are making an android application with java. And it all works fine but there is an exceptional case when the application tries to get the file from storage and the file doesn’t exist (This is the case of exception in java). And if this case is not handled properly then the application will crash. This will be a bad experience for users. This is the type of error that cannot be controlled by the programmer. But programmers can take some steps to avoid this so that the application won’t crash. The proper action can be taken at this step.
33
Is it mandatory for a catch block to be followed after a try block?
https://stackoverflow.com/questions/6703085/is-it-necessary-to-put-catch-statements-after-a-try-block
34
Can you call a constructor of a class inside another constructor?
https://www.javatpoint.com/what-is-constructor-chaining-in-java
35
Contiguous memory locations are usually used for storing actual values in an array but not in ArrayList. Explain.
Primitive data types like int, float, and others are typically present in an array. In such circumstances, the array immediately saves these elements at contiguous memory regions. While an ArrayList does not contain primitive data types. Instead of the actual object, an ArrayList includes the references to the objects' many locations in memory. The objects are not kept in consecutive memory regions because of this.
36
Why does the java array index start with 0?
https://stackoverflow.com/questions/24841172/why-does-array-indexing-in-java-start-with-0#:~:text=The%20index%20in%20an%20array,Therefore%20the%20offset%20is%200.
37
Why is the remove method faster in the linked list than in an array?
https://www.baeldung.com/java-arraylist-vs-linkedlist-vs-hashmap#:~:text=The%20insertion%2C%20addition%2C%20and%20removal,surrounding%20elements%20need%20to%20change.
38
Difference between LinkedList, ArrayList and HashMap
https://www.baeldung.com/java-arraylist-vs-linkedlist-vs-hashmap#:~:text=The%20insertion%2C%20addition%2C%20and%20removal,surrounding%20elements%20need%20to%20change.
39
How many overloaded add() and addAll() methods are available in the List interface?
https://www.digitalocean.com/community/tutorials/java-list-add-addall-methods
40
How does the size of ArrayList grow dynamically?
https://www.javaguides.net/2018/08/how-size-of-arraylist-increases-dynamically.html#google_vignette
41
Although inheritance is a popular OOPs concept, it is less advantageous than composition. Explain.
https://www.thoughtworks.com/insights/blog/composition-vs-inheritance-how-choose
42
What are Composition and Aggregation? State the difference.
https://www.geeksforgeeks.org/difference-between-aggregation-and-composition-in-java/#:~:text=Aggregation%20can%20be%20described%20as,is%20contained%20in%20another%20object.
43
How is string literal different from string object
https://www.geeksforgeeks.org/string-initialization-java-string-literal-vs-string-object/
44
new Operator vs newInstance() Method in Java
https://www.geeksforgeeks.org/new-operator-vs-newinstance-method-java/#:~:text=In%20Java%2C%20new%20is%20an,newInstance()%20method%20is%20used.
45
Is exceeding the memory limit possible in a program despite having a garbage collector?
Yes, even with a garbage collector in place, the programme could still run out of memory. Garbage collection aids in identifying and removing programme objects that are no longer needed in order to release the resources they use. When an object in a programme cannot be reached, trash collection is executed with respect to that object. If there is not enough memory available to create new objects, a garbage collector is used to free up memory for things that have been removed from the scope. When the amount of memory released is insufficient for the creation of new objects, the program's memory limit is exceeded.
46
What is Multithreading in Java
https://www.scaler.com/topics/multithreading-in-java/
https://www.digitalocean.com/community/tutorials/multithreading-in-java
47
Why is synchronization necessary?
https://www.javatpoint.com/synchronization-in-java
48
Define System.out.println().
https://www.tutorialspoint.com/system-out-println-in-java#:~:text=Introduction,the%20execution%20of%20a%20program.
49
Life cycle of a Thread (Thread States)
https://www.javatpoint.com/life-cycle-of-a-thread
50
What could be the tradeoff between the usage of an unordered array versus the usage of an ordered array?
https://stackoverflow.com/questions/54027951/difference-between-sorted-and-unsorted-array-time-complexity
51
Is it possible to import the same class or package twice in Java and what happens to it during runtime?
The same package or class may be imported more than once. Neither the JVM nor the compiler raise an objection. Even if you import the same class several times, the JVM will only internally load it once.
52
In case a package has sub packages, will it suffice to import only the main package? e.g. Does importing of com.myMainPackage.* also import com.myMainPackage.mySubPackage.*?
Sub-packages won't be imported when a package is imported. When you import a package, all of its classes and interfaces—with the exception of those from its sub-packages—are imported.
This is a big NO. We need to understand that the importing of the sub-packages of a package needs to be done explicitly. Importing the parent package only results in the import of the classes within it and not the contents of its child/sub-packages.
53
Will the final block be executed if the code System.exit(0) is written at the end of the try block?
The system is established as the last line to be run, after which nothing will happen, therefore both the catch and finally blocks are essentially ignored.
54
Explain the term “Double Brace Initialisation” in Java?
https://www.javatpoint.com/double-brace-initialization-in-java#:~:text=Double%20brace%20initialization%20is%20a,within%20the%20instantiation%20code%20block.
55
Why is it said that the length() method of String class doesn't return accurate results?
https://arc.dev/developer-blog/java-interview-questions/#:~:text=length()%20accurate%3F,of%20U%2B10000%20or%20greater.
Experienced Question 18
https://www.interviewbit.com/java-interview-questions/
56
How to make object eligible for garbage collection in Java?
https://www.geeksforgeeks.org/how-to-make-object-eligible-for-garbage-collection/
57
What is the best way to inject dependency? Also, state the reason.
https://www.geeksforgeeks.org/what-is-the-best-way-to-inject-dependency-in-java/
58
Bean scopes in JSF
https://stackoverflow.com/questions/7031885/how-to-choose-the-right-bean-scope
59
Bean scopes in Spring
https://www.digitalocean.com/community/tutorials/spring-bean-scopes
60
Design patterns in Java
https://www.geeksforgeeks.org/java-design-patterns/
Experienced Question 24
https://www.interviewbit.com/java-interview-questions/
61
What is a Memory Leak? Discuss some common causes of it
https://www.baeldung.com/java-memory-leaks#:~:text=A%20Memory%20Leak%20is%20a,degrades%20system%20performance%20over%20time.
62
Assume a thread has a lock on it, calling the sleep() method on that thread will release the lock?
No, the thread might release the locks using notify, notifyAll(), and wait() methods.
63
Java Programming simple
Refer 65 to 74 from
https://www.simplilearn.com/tutorials/java-tutorial/java-interview-questions#GoTop
64
What is the difference between JDK, JRE, and JVM?
JVM has a Just in Time (JIT) compiler tool that converts all the Java source code into the low-level compatible machine language. Therefore, it runs faster than the regular application.
JRE has class libraries and other JVM supporting files. But it doesn’t have any tool for java development such as compiler or debugger.
JDK has tools that are required to write Java Programs and uses JRE to execute them. It has a compiler, Java application launcher, and an applet viewer.
65
What is a JIT compiler?
https://www.javatpoint.com/jit-in-java
Question No 10 from
https://www.interviewbit.com/java-interview-questions/
66
What are Brief Access Specifiers and Types of Access Specifiers?
Access Specifiers are predefined keywords used to help JVM understand the scope of a variable, method, and class. We have four access specifiers.
Public Access Specifier
Private Access Specifier
Protected Access Specifier
Default Access Specifier
https://www.javatpoint.com/access-modifiers
67
Types of Constructors in Java
https://www.digitalocean.com/community/tutorials/constructor-in-java
68
Can a constructor return a value?
Yes, A constructor can return a value. It replaces the class's current instance implicitly; you cannot make a constructor return a value explicitly.
https://www.javatpoint.com/java-constructor-returns-a-value-but-what
69
Explain ‘this’ keyword in Java.
https://www.javatpoint.com/this-keyword
70
OOPs principles
https://www.linkedin.com/pulse/7-oops-principles-every-programmer-should-know-harsh-sakhiya?utm_source=share&utm_medium=member_ios&utm_campaign=share_via
And
Let us Java page 250
71
Super Keyword in Java
https://www.geeksforgeeks.org/super-keyword/
72
Explain Method Overloading in Java.
The process of creating multiple method signatures using one method name is called Method Overloading in Java. Two ways to achieve method overloading are:
Varying the number of arguments
Changing the return type of the Method
https://www.javatpoint.com/method-overloading-in-java
73
Can we overload a static method?
No, Java does not support the Overloading of a static method. The process would throw an error reading "static method cannot be referenced."
74
Late binding in Java
https://www.linkedin.com/pulse/early-late-binding-java-pramod-yadav?utm_source=share&utm_medium=member_ios&utm_campaign=share_via
75
Overriding in Java
https://www.geeksforgeeks.org/overriding-in-java/
76
Polymorphism in Java
https://www.geeksforgeeks.org/polymorphism-in-java/
77
Define Dynamic Method Dispatch.
The Dynamic method dispatch is a process where the method call is executed during the runtime. A reference variable is used to call the super-class. This process is also known as Run-Time Polymorphism.
78
Why is the delete function faster in the linked list than an array?
https://www.quora.com/Computer-Programming-Why-is-the-delete-function-faster-in-the-linked-list-than-an-array
https://www.baeldung.com/java-arraylist-vs-linkedlist-vs-hashmap#:~:text=The%20insertion%2C%20addition%2C%20and%20removal,surrounding%20elements%20need%20to%20change.
79
Difference between Array and Arraylists
https://www.javatpoint.com/difference-between-array-and-arraylist
80
Lifecycle and States of a Thread in Java
https://www.geeksforgeeks.org/lifecycle-and-states-of-a-thread-in-java/
81
difference between >> and >>> operators
https://www.geeksforgeeks.org/what-is-javascript-operator-and-how-to-use-it/#:~:text=Difference%20between%20%3E%3E%3E%20and%20%3E,the%20integer%20value%20when%20shifted.
82
Applets and their lifecycle
https://www.geeksforgeeks.org/java-applet-basics/
83
Why are generics used in Java Programming?
Compile-time type safety is provided by using generics. Compile-time type safety allows users to catch unnecessary invalid types at compile time. Generic methods and classes help programmers specify a single method declaration, a set of related methods, or related types with an available class declaration.
https://www.oracle.com/technical-resources/articles/java/juneau-generics.html
84
Serializable and Externalizable interfaces in Java
https://www.geeksforgeeks.org/externalizable-interface-java/
85
Enum in Java
https://www.freecodecamp.org/news/java-enum-enumeration-in-java-example/#:~:text=An%20enumeration%20(enum%20for%20short,%2C%20colors%2C%20and%20so%20on.
https://www.geeksforgeeks.org/enum-in-java/
86
Why is Java Dynamic
https://www.cesarsotovalero.net/blog/the-dynamic-features-of-java.html
87
Can you run a code before executing the main method?
Yes, we can execute any code, even before the main method. We will be using a static block of code when creating the objects at the class's load time. Any statements within this static block of code will get executed at once while loading the class, even before creating objects in the main method.
88
How many times is the finalize method called?
https://www.tutorialspoint.com/how-many-times-finalize-method-will-be-invoked-who-invokes-finalize-method-in-java#:~:text=It%20is%20invoked%20only%20once,override%20it%20from%20any%20class.
89
Can "this" and "super" keywords be used together?
https://stackoverflow.com/questions/10381244/why-cant-this-and-super-both-be-used-together-in-a-constructor
https://www.quora.com/Can-you-use-this-and-super-both-in-a-constructor#:~:text=NO.,()%20but%20not%20the%20both.
90
Why does this() and super() have to be the first statement in a constructor?
https://www.quora.com/Why-does-this-and-super-have-to-be-the-first-statement-in-a-constructor
91
What is a JSP page?
https://www.geeksforgeeks.org/introduction-to-jsp/
92
What is JDBC?
https://www.javatpoint.com/java-jdbc
93
Explain the various directives in JSP
https://www.geeksforgeeks.org/introduction-to-jsp/
94
What are the observer and observable classes?
https://stackoverflow.com/questions/13744450/when-should-we-use-observer-and-observable
https://stackoverflow.com/questions/70949886/observer-and-observable-got-deprecated-and-the-reason-stated-is-they-convey-som
https://www.oreilly.com/library/view/learning-java-4th/9781449372477/ch11s08.html
95
What is Session Management in Java?
https://www.educba.com/servlet-session-management/#:~:text=Servlet%20Session%20Management%20is%20a,Cookies%2C%20URL%20rewriting%2C%20etc.
96
Briefly explain the term Spring Framework.
https://docs.spring.io/spring-framework/docs/3.2.x/spring-framework-reference/html/overview.html#:~:text=Spring%20Framework%20is%20a%20Java,can%20focus%20on%20your%20application.
97
How to handle exceptions in Spring MVC Framework?
https://medium.com/@AlexanderObregon/the-art-of-handling-exceptions-with-exceptionhandler-in-spring-mvc-dfb956d84aef#:~:text=Instead%20of%20defining%20the%20same,ControllerAdvice%20to%20handle%20exceptions%20globally.&text=With%20%40ControllerAdvice%20%2C%20any%20exception%20thrown,will%20be%20caught%20and%20handled.
98
What is JCA in Java?
https://www.educative.io/answers/what-is-java-cryptography-architecture-jca
99
Explain JPA in Java.
https://www.javatpoint.com/jpa-introduction
https://www.ibm.com/docs/en/was-liberty/nd?topic=liberty-java-persistence-api-jpa
The Java Persistence API enables us to create the persistence layer for desktop and web applications. Java Persistence deals in the following:
Java Persistence API
Query Language
Java Persistence Criteria API
Object Mapping Metadata
100
Explain the different authentications in Java Servlets.
https://www.careerride.com/j18.aspx
101
Explain FailFast iterator and FailSafe iterator along with examples for each.
https://anmolsehgal.medium.com/fail-fast-and-fail-safe-iterations-in-java-collections-11ce8ca4180e#:~:text=Fail%2Dsafe%20iterators%20means%20they,modified%20while%20iterating%20over%20it.&text=As%20arrayLists%20are%20fail%2Dfast%20above%20code%20will%20throw%20an%20exception.
102
Programming questions 111 to 118 from the link below
https://www.simplilearn.com/tutorials/java-tutorial/java-interview-questions#GoTop
103
What do you understand by an instance variable and a local variable?
https://www.geeksforgeeks.org/difference-between-instance-variable-and-local-variable/
104
Can the main method be overloaded?
https://www.geeksforgeeks.org/how-to-overload-and-override-main-method-in-java/#:~:text=Yes%2C%20We%20can%20overload%20the,call%20our%20overloaded%20main%20method.
105
Difference Between Method Overloading and Method Overriding in Java
https://www.geeksforgeeks.org/difference-between-method-overloading-and-method-overriding-in-java/
106
Is it possible to have multiple try blocks with only one catch block in java?
https://www.tutorialspoint.com/is-it-possible-to-have-multiple-try-blocks-with-only-one-catch-block-in-java#:~:text=You%20cannot%20have%20multiple%20try,compile%20time%20error%20is%20generated.
107
Java - Multi catch block with Examples
https://www.tutorialspoint.com/java/java_multi_catch_block.htm
108
Do final, finally and finalize keywords have the same function?
https://www.javatpoint.com/difference-between-final-finally-and-finalize
109
When can you use the "super" keyword?
Basically, the super keyword is used to refer to the parent class. When there are the same fields in both parent and child classes, then one can use a super keyword to access data members of the parent class.
110
What are shallow copy and deep copy in Java?
In the case of a shallow copy, primitive data types are copied, whereas in the case of a deep copy along with primitive data types the object references are also copied.
https://www.javatpoint.com/shallow-copy-vs-deep-copy-in-java
111
differences between interfaces and abstract classes.
https://www.geeksforgeeks.org/difference-between-abstract-class-and-interface-in-java/
112
What are the different ways of thread usage?
There are two ways to define and implement a thread in Java. They are by implementing the runnable interface and extending the thread class.
https://www.simplilearn.com/tutorials/java-tutorial/java-interview-questions#GoTop
113
What is the difference between the ‘throw' and ‘throws' keyword in Java?
https://www.geeksforgeeks.org/difference-between-throw-and-throws-in-java/#:~:text=The%20throw%20keyword%20is%20used%20to%20throw%20an%20exception%20explicitly,ones%2C%20is%20thrown%20automatically%20then.
114
Java works as a “pass by value” or “pass by reference” phenomenon?
https://www.javatpoint.com/java-pass-by-value#:~:text=It%20is%20really%20confusing%20and,pass%20by%20reference%20in%20Java.
115
How to not allow serialization of attributes of a class in Java?
https://elearning.uou.ac.in/mod/forum/discuss.php?d=591&parent=1083
Question 24 Intermediate
https://www.interviewbit.com/java-interview-questions/
116
What are the default values assigned to variables and instances in Java?
By default, for a numerical value it is 0, for the boolean value it is false and for objects it is NULL.
Question 8 from
https://www.interviewbit.com/java-interview-questions/
117
What do you mean by data encapsulation?
http://www.cs.mun.ca/~donald/bsc/node13.html#:~:text=Data%20encapsulation%2C%20sometimes%20referred%20to,special%20functions%20commonly%20called%20methods.
118
Explain inheritance
http://www.cs.mun.ca/~donald/bsc/node14.html#SECTION00432000000000000000
https://www.geeksforgeeks.org/inheritance-in-java/
119
Can you tell the difference between equals() method and equality operator (==) in Java?
https://www.linkedin.com/pulse/difference-between-equals-java-babar-shahzad?utm_source=share&utm_medium=member_ios&utm_campaign=share_via
120
Briefly explain the concept of constructor overloading
https://www.geeksforgeeks.org/constructor-overloading-java/
121
Explain the use of the final keyword in variable, method and class.
https://www.javatpoint.com/final-keyword
122
Is it possible that the ‘finally' block will not be executed? If yes then list the case.
Yes, there is a possibility that the ‘finally’ block cannot get executed. Here are some of the cases where the above situation occurs.
During the time of fatal errors such as memory exhaustion, memory access error, etc.
During the time of using System.exit()
https://www.scientecheasy.com/2020/05/java-finally-block-not-executed.html/
123
Difference between static methods, static variables, and static classes in Java.
https://stackoverflow.com/questions/52935433/what-is-difference-between-static-variable-and-static-method-and-static-class
124
Apart from the security aspect, what are the reasons behind making strings immutable in Java?
Because of security, synchronization, concurrency, caching, and class loading, the String is immutable in Java. The reason for making string final would be to destroy its immutability and help stop others from trying to extend it. String objects are cached in the String pool, making them immutable.
https://www.upgrad.com/tutorials/software-engineering/java-tutorial/why-string-is-immutable-in-java/#:~:text=If%20the%20string%20was%20not,security%20threat%20to%20the%20application.
125
How would you differentiate between a String, StringBuffer, and a StringBuilder?
https://www.geeksforgeeks.org/string-vs-stringbuilder-vs-stringbuffer-in-java/
126
What is a Comparator in Java?
https://www.geeksforgeeks.org/comparator-interface-java/
127
In Java, static as well as private method overriding is possible. Comment on the statement.
In Java, you could indeed override a private or static method. If you create a similar method in a child class with the same return type and method arguments, it will hide the super class method; this is known as method hiding. Similarly, you cannot override a private method in a subclass because it is not accessible from that.
128
What makes a HashSet different from a TreeSet?
https://www.geeksforgeeks.org/hashset-vs-treeset-in-java/
129
Why is the character array preferred over string for storing confidential information?
https://www.geeksforgeeks.org/use-char-array-string-storing-passwords-java/
130
What are the differences between HashMap and HashTable in Java?
https://www.geeksforgeeks.org/differences-between-hashmap-and-hashtable-in-java/
131
What is the importance of reflection in Java?
https://www.geeksforgeeks.org/reflection-in-java/#:~:text=Reflection%20gives%20us%20information%20about,access%20specifier%20used%20with%20them.
132
What are the different types of Thread Priorities in Java? And what is the default priority of a thread assigned by JVM?
https://www.geeksforgeeks.org/java-thread-priority-multithreading/
133
What is the ‘IS-A ‘ relationship in OOPs Java?
https://www.geeksforgeeks.org/what-is-is-a-relationship-in-java/
134
Can static methods be overridden?
https://www.geeksforgeeks.org/can-we-overload-or-override-static-methods-in-java/
135
What are the different ways of thread usage?
https://www.geeksforgeeks.org/java-program-to-create-a-thread/
136
How do you achieve Object Cloning in Java?
https://www.geeksforgeeks.org/clone-method-in-java-2/
137
What are the advantages of Packages in Java?
https://techvidvan.com/tutorials/packages-in-java/
138
Difference between static (class) method and instance method
https://www.geeksforgeeks.org/static-methods-vs-instance-methods-java/
139
How can constructor chaining be done using this keyword?
https://www.baeldung.com/java-chain-constructors#:~:text=Constructor%20chaining%20is%20the%20process,constructors%20from%20the%20parent%20class
140
Which class is the superclass for all the classes?
https://www.tutorialspoint.com/why-object-class-is-the-super-class-for-all-classes-in-java
141
Why are multiple inheritances not supported in Java?
https://www.digitalocean.com/community/tutorials/multiple-inheritance-in-java#:~:text=Diamond%20Problem%20in%20Java&text=This%20leads%20to%20the%20ambiguity,support%20multiple%20inheritances%20in%20classes.
142
Why is method overloading not possible by changing the return type in Java?
https://www.quora.com/Why-is-method-overloading-not-possible-by-changing-the-return-type-in-Java#:~:text=In%20java%2C%20method%20overloading%20is,because%20there%20may%20occur%20ambiguity.
143
What is method overloading with type promotion?
https://www.c-sharpcorner.com/UploadFile/3614a6/type-promotion-in-java/#:~:text=Type%20promotion%20is%20done%20while,one%20datatype%20to%20another%20datatype.
144
Can we change the scope of the overridden method in the subclass?
https://stackoverflow.com/questions/9330001/change-the-access-modifier-of-an-overridden-method-in-java
https://www.krayonnz.com/user/doubts/detail/63dcc32303de5b005f49e961/can-we-change-the-scope-of-the-overridden-method-in-the-subclass#:~:text=Yes%2C%20we%20can%20change%20the,protected%2C%20public%2C%20or%20default.
145
Can you have virtual functions in Java?
https://stackoverflow.com/questions/4547453/can-you-write-virtual-functions-methods-in-java
146
What is the covariant return type?
https://www.geeksforgeeks.org/covariant-return-types-java/
147
What is the final blank variable?
https://www.javatpoint.com/final-keyword#:~:text=Q)%20What%20is%20blank%20or,be%20changed%2C%20it%20is%20useful.
148
Difference between the final method and the abstract method
https://www.geeksforgeeks.org/difference-between-final-and-abstract-in-java/
149
Differences between Heap and Stack Memory in Java
https://www.digitalocean.com/community/tutorials/java-heap-space-vs-stack-memory#:~:text=Heap%20memory%20is%20used%20by,contains%20the%20reference%20to%20it.
150
How is Java different from C++?
https://www.javatpoint.com/cpp-vs-java#:~:text=C%2B%2B%20is%20compiled%20and%20run,at%20runtime%20and%20produces%20output.
151
Pointers are used in C/ C++. Why does Java not make use of pointers?
https://www.c-sharpcorner.com/interview-question/why-java-does-not-support-pointers#:~:text=A%20pointer%20is%20a%20variable,restriction%20even%20variable%20is%20private.
152
Explain the use of final keyword in variable, method and class.
Question 18 from
https://www.interviewbit.com/java-interview-questions/
153
Do final, finally and finalize keywords have the same function?
Question 19 from
https://www.interviewbit.com/java-interview-questions/
154
Apart from the security aspect, what are the reasons behind making strings immutable in Java?
Intermediate question 1 from
https://www.interviewbit.com/java-interview-questions/
155
What do we get in the JDK file?
Intermediate Question 11
https://www.interviewbit.com/java-interview-questions/
156
Can we make the main() thread a daemon thread?
https://www.geeksforgeeks.org/daemon-thread-java/#:~:text=By%20default%2C%20the%20main%20thread,is%20also%20a%20non%2Ddaemon.
157
Will the finally block get executed when the return statement is written at the end of try block and catch block as shown below?
finally block will be executed irrespective of the exception or not. The only case where finally block is not executed is when it encounters ‘System.exit()’ method anywhere in try/catch block.
158
Contiguous memory locations are usually used for storing actual values in an array but not in ArrayList. Explain.
Intermediate 35
https://www.interviewbit.com/java-interview-questions/
159
Why does the java array index start with 0?
Question 36
https://www.interviewbit.com/java-interview-questions/
160
How many overloaded add() and addAll() methods are available in the List interface? Describe the need and uses.
Intermediate 38
https://www.interviewbit.com/java-interview-questions/
161
How does the size of ArrayList grow dynamically? And also state how it is implemented internally.
Question 39
https://www.interviewbit.com/java-interview-questions/
162
Although inheritance is a popular OOPs concept, it is less advantageous than composition. Explain.
https://www.digitalocean.com/community/tutorials/composition-vs-inheritance
Question 1 Experienced
https://www.interviewbit.com/java-interview-questions/
163
What is the difference between ‘>>’ and ‘>>>’ operators in java?
Question 2 experienced
https://www.interviewbit.com/java-interview-questions/
164
How is the ‘new’ operator different from the ‘newInstance()’ operator in java?
https://www.geeksforgeeks.org/new-operator-vs-newinstance-method-java/#:~:text=In%20Java%2C%20new%20is%20an,newInstance()%20method%20is%20used.
165
Why is synchronization necessary? Explain with the help of a relevant example.
Question 7 experienced
https://www.interviewbit.com/java-interview-questions/
166
Experienced Questions 8 and 9
https://www.interviewbit.com/java-interview-questions/
167
Is it possible to import the same class or package twice in Java and what happens to it during runtime?
It is possible to import a class or package more than once, however, it is redundant because the JVM internally loads the package or class only once.
168
Assume a thread has a lock on it, calling the sleep() method on that thread will release the lock?
A thread that has a lock won't be released even after it calls sleep(). Despite the thread sleeping for a specified period of time, the lock will not be released.
169
Differentiate between Volatile and Transient Variable in Java.
https://naveen-metta.medium.com/understanding-transient-and-volatile-variables-in-java-2af7bc534bde#:~:text=Transient%20variables%20help%20in%20excluding,caused%20by%20caching%20or%20optimization.
170
Differentiate between the Vector and ArrayList collections in Java.
https://www.geeksforgeeks.org/vector-vs-arraylist-java/
Question 2 from
https://www.interviewbit.com/java-interview-questions-for-5-years-experience/
171
How is Collection different from Collections in Java?
https://www.geeksforgeeks.org/collection-vs-collections-in-java-with-example/
172
code for representing thread-safe singleton patterns in Java?
Question 5 from
https://www.interviewbit.com/java-interview-questions-for-5-years-experience/
173
What is the importance of the hashCode() and equals() contract?
https://bulldogjob.com/readme/how-not-to-break-your-app-with-hashcode-and-equals#:~:text=hashCode()%20and%20equals()%20contract,equals()%20can%20return%20false.
Question 6
https://www.interviewbit.com/java-interview-questions-for-5-years-experience/
174
How is the classpath variable different from the path variables?
https://www.linkedin.com/pulse/difference-between-path-classpath-shivani-verma?utm_source=share&utm_medium=member_ios&utm_campaign=share_via
175
Can we use HashMap in a multi-threaded environment?
https://stackoverflow.com/questions/11050539/using-hashmap-in-multithreaded-environment
https://www.quora.com/What%E2%80%99s-wrong-with-using-HashMap-in-a-multithreaded-environment-when-the-get-method-goes-to-an-infinite-loop
176
What will happen if you run 1.0/0.0?
The double class provides certain rules like Double.INFINITY, NaN, -0.0, etc which aids in arithmetic calculations. The given problem will return Double.INFINITY without throwing any Arithmetic Exception.
177
Is it possible to override a method to throw RuntimeException from throwing NullPointerException in the parent class?
Yes, this is possible. But it is not possible if the parent class has a checked Exception. This is due to the below rule of method overriding in cases of checked exceptions:
The method that wants to override a parent class method can not throw a higher Exception than the overridden method.
This means that if the overridden method is throwing IOException, then the overriding child class method can only throw IOException or its sub-classes. This overriding method can not throw a higher Exception than the original or overridden method.
178
Is there any difference in defining or creating a String by using String literal and by using the new() operator?
Creating string using the new operator ensures that the String is created in the heap alone and not into the string pool. Whereas, creating string using literal ensures that the string is created in the string pool. String pool exists as part of the perm area in the heap. This ensures that the multiple Strings created using literal having same values are pointed to one object and prevents duplicate objects with the same value from being created.
179
Is it necessary to declare all immutable objects as final?
This is not necessary. The functionality of achieving immutability can also be achieved by defining the members of a class as private and not providing any setter methods to modify/update the values. Any references to the members should not be leaked and the only source of initializing the members should be by using the parameterized constructor.
We should note that the variables declared as final only takes care of not re-assigning the variable to a different value. The individual properties of an object can still be changed.
180
What do you know about Factory Design Pattern in Java?
https://www.digitalocean.com/community/tutorials/factory-design-pattern-in-java#:~:text=The%20factory%20design%20pattern%20is,program%20to%20the%20factory%20class.
181
What is a deadlock and discuss the necessary conditions for deadlock?
https://www.javatpoint.com/deadlock-in-java
https://www.scaler.com/topics/operating-system/deadlock-in-os/#:~:text=A%20deadlock%20in%20OS%20is,and%20wait%20and%20circular%20set.
182
Differentiate between multitasking and multithreading?
https://www.geeksforgeeks.org/difference-between-multi-tasking-and-multi-threading/
183
Differentiate between thread and process?
https://www.geeksforgeeks.org/difference-between-process-and-thread/
184
What is an object oriented model?
https://www.geeksforgeeks.org/basic-object-oriented-data-model/
185
You are given the head of a linked list, to determine whether the cycle is present in the linked list. Approach?
One common approach to detect a cycle in a linked list is the two pointer technique, often called Floyd's Cycle Detection Algorithm. Here's the simple explanation:
We use two pointers, one slow (moving one step at a time) and another fast (moving two steps at a time). We start at the head of the linked list and move both pointers according to their rules. If the linked list has a cycle, the fast pointer will eventually catch up to the slow pointer. If it doesn't, the fast pointer will reach the end of the list.
186
Problem statement: You are given an array nums having n integers colored red, white, or blue, sort them in place so that objects of the same color are adjacent, with the colors in the order red, white, and blue. Approaches?
This problem is also known as the Dutch National Flag problem. The easiest approach to solve this problem is to use a two-pass algorithm.
In the first pass, count the number of red, white, and blue elements. In the second pass, overwrite the array with the right number of red, white, and blue elements in the correct order.
Alternatively, a more efficient one-pass algorithm can be used, which involves three pointers: one for the current element, one for the end of the red elements and one for the start of the blue elements. As you iterate through the array, swap elements to move them to the right place.
187
Differentiate between super key and primary key?
https://www.geeksforgeeks.org/difference-between-primary-key-and-super-key/#:~:text=Difference%20between%20Super%20Key%20and%20Primary%20Key%3A&text=1.-,Super%20Key%20is%20an%20attribute%20(or%20set%20of%20attributes)%20that,all%20attributes%20in%20a%20relation.
188
How UNION is different from UNION ALL?
https://www.atlassian.com/data/sql/what-is-the-difference-between-union-and-union-all#:~:text=The%20main%20difference%20between%20UNION,keeps%20all%20records%2C%20including%20duplicates
189
Define Bus Topology.
https://www.computerhope.com/jargon/b/bustopol.htm
190
Generics in Java
https://www.javatpoint.com/generics-in-java
191
Concurrenthashmap in Java. How is it different from Hashmap
https://www.geeksforgeeks.org/concurrenthashmap-in-java/
https://www.geeksforgeeks.org/difference-hashmap-concurrenthashmap/
192
How to prevent Singleton Pattern from Reflection, Serialization and Cloning?
https://www.geeksforgeeks.org/prevent-singleton-pattern-reflection-serialization-cloning/#:~:text=Overcome%20Cloning%20issue%3A%20To%20overcome,hence%20our%20class%20remains%20singleton.
193
HashMap in Java
https://www.geeksforgeeks.org/java-util-hashmap-in-java-with-examples/
194
Disadvantage of Multithreading in Java
https://www.javatpoint.com/disadvantage-of-multithreading-in-java
195
Concurrent Hashmap how it works? why is better than synchronised block?
https://stackoverflow.com/questions/12628600/java-synchronized-block-vs-concurrenthashmap-vs-collections-synchronizedmap
https://www.geeksforgeeks.org/difference-between-concurrenthashmap-and-synchronizedhashmap/
196
how to achieve locking? difference between lock and shynchronised
https://stackoverflow.com/questions/4201713/synchronization-vs-lock
https://www.geeksforgeeks.org/lock-framework-vs-thread-synchronization-in-java/#:~:text=Lock%20framework%20works%20like%20synchronized,below%2Dmentioned%20problem%20of%20synchronization.
197
Future, callable, executor service.
https://www.digitalocean.com/community/tutorials/java-callable-future-example
https://dzone.com/articles/basics-of-using-java-future-and-executor-service
198
how to optimise a query if you find out its slow?
https://www.thoughtspot.com/data-trends/data-modeling/optimizing-sql-queries
199
S.O.L.I.D principle with examples.
https://www.geeksforgeeks.org/solid-principle-in-programming-understand-with-real-life-examples/
200
Streams in Java
https://www.geeksforgeeks.org/stream-in-java/
201
can we run Class in Java 1.4 which was compiled in java 1.5
https://stackoverflow.com/questions/1710933/will-jre-1-4-support-classes-compiled-with-java-1-5-1-6
202
How to create Immutable class in Java?
https://www.geeksforgeeks.org/create-immutable-class-java/
203
difference between Java singleton and spring singleton?
https://stackoverflow.com/questions/15252284/what-is-the-difference-between-a-spring-singleton-and-a-java-singeletondesign-p
204
Internal Working of HashMap in Java
https://www.geeksforgeeks.org/internal-working-of-hashmap-java/
205
Java Singleton Design Pattern
https://www.geeksforgeeks.org/java-singleton-design-pattern-practices-examples/
206
Describe Loose Coupling and Cohesion.
https://stackoverflow.com/questions/14000762/what-does-low-in-coupling-and-high-in-cohesion-mean
207
Benefit of using Abstract classes and Abstract methods
https://medium.com/@dilip.voleti/benefit-of-using-abstract-classes-and-abstract-methods-c1d0bdc74864
208
If I have a list of Strings, how will I remove the duplicates from it?
https://pandaquests.medium.com/removing-duplicates-from-a-list-in-java-37ccfce4de6e#:~:text=To%20remove%20duplicates%20from%20a%20list%20in%20Java%2C%20you%20can,duplicates%20will%20automatically%20be%20removed.
209
What is return type of Set ?
https://www.geeksforgeeks.org/set-in-java/#:~:text=It%20returns%20an%20integer%20value,this%20instance%20of%20the%20Set.&text=isEmpty()-,This%20method%20is%20used%20to%20check,set%20is%20empty%20or%20not.&text=This%20method%20is%20used%20to%20return%20the%20iterator%20of%20the,returned%20in%20a%20random%20order.
210
Does An abstract class required to have an abstract method inside
https://stackoverflow.com/questions/4811678/defining-an-abstract-class-without-any-abstract-methods
211
Why not serialize abstract classes in Java
https://stackoverflow.com/questions/4452941/why-not-serialize-abstract-classes-in-java
212
The new features in Java 21
https://www.infoworld.com/article/3689880/jdk-21-the-new-features-in-java-21.html
213
Difference Between Streams and Collections in Java
https://www.geeksforgeeks.org/difference-between-streams-and-collections-in-java/
214
Functional Interfaces in Java
https://www.geeksforgeeks.org/functional-interfaces-java/#:~:text=A%20functional%20interface%20is%20an,any%20number%20of%20default%20methods.
215
Static and Default Methods in Interfaces in Java
https://www.baeldung.com/java-static-default-methods
216
Lambda Expression in Java
https://www.geeksforgeeks.org/lambda-expressions-java-8/
217
Method References in Java
https://www.baeldung.com/java-method-references#:~:text=Method%20references%20are%20a%20special,Instance%20methods%20of%20particular%20objects
218
Pros and Cons of using Optional Objects in Java
https://www.developer.com/java/java-optional-object/#:~:text=Optional%20can%20help%20to%20prevent,or%20may%20not%20be%20present.
219
How to sort a Map in Java
https://mkyong.com/java/how-to-sort-a-map-in-java/
220
Try-with-resources Feature in Java
https://www.geeksforgeeks.org/try-with-resources-feature-in-java/
221
How to investigate the cause of a JVM crash
https://stackoverflow.com/questions/8152393/how-do-i-investigate-the-cause-of-a-jvm-crash
https://www.site24x7.com/learn/troubleshoot-jvm-crashes.html
222
How to find server crash reasons
https://aloa.co/blog/why-does-a-server-crash
223
How to find max memory, free memory and total memory in Java?
https://www.geeksforgeeks.org/find-max-memory-free-memory-total-memory-java/
224
How to find out server load and memory in Linux & Windows
https://customer.precisely.com/s/article/How-to-find-out-server-load-and-memory-in-Linux-Windows-360041278854?language=en_US
225
What is Caching and how can you implement your Cache ?
https://www.geeksforgeeks.org/what-is-the-caching-mechanism/
https://www.javatpoint.com/lru-cache-implementation-in-java#:~:text=A%20class%20Cache%20is%20implemented,the%20values%20for%20both%20variables.
226
Difference between UNIX and Windows Operating System
https://www.geeksforgeeks.org/difference-between-unix-and-windows-operating-system/
227
Clone a Linked List with next and Random Pointer
https://www.geeksforgeeks.org/a-linked-list-with-next-and-arbit-pointer/
228
When programming in Java, can you have an empty catch block?
While you can use an empty catch block while programming in Java, it is not advised. The problem this creates involves debugging the program if the empty catch block were to catch an exception. There will not be any information about the exception. Finding the issue with no information in the log could be very time-consuming."
229
How does an OutOfMemoryError impact a program written in Java, and how can this be corrected?
An OutOfMemoryError is created by the JVM when there is no memory available for it to use. This will result in a program halting. The simple way to fix this is to allocate more memory to run in the java application."
230
CountDownLatch in Java
https://www.geeksforgeeks.org/countdownlatch-in-java/
231
Difference Between Daemon Threads and User Threads In Java
https://www.geeksforgeeks.org/difference-between-daemon-threads-and-user-threads-in-java/#:~:text=A%20user%20thread%20can%20keep,used%20for%20any%20critical%20task.
232
Static import in Java
https://www.geeksforgeeks.org/static-import-java/
233
volatile keyword in Java
https://medium.com/codex/volatile-keyword-in-java-9e8792b4e6ba#:~:text=The%20volatile%20keyword%20in%20Java,value%20for%20the%20volatile%20variable.
234
Main() in Java
https://www.geeksforgeeks.org/java-main-method-public-static-void-main-string-args/
235
Methods in object class
https://www.geeksforgeeks.org/object-class-in-java/
236
Exception hierarchy in Inheritance
https://www.geeksforgeeks.org/exception-handling-with-method-overriding-in-java/
237
Why is checked exception also called compile time exception. Does it occur compile time?
https://stackoverflow.com/questions/50549579/checked-exception-is-compile-time-or-runtime#:~:text=2%20Answers&text=Checked%20exceptions%20are%20checked%20at,containing%20method%20throws%20the%20exception.
238
User-defined Custom Exception in Java
https://www.geeksforgeeks.org/user-defined-custom-exception-in-java/
239
String Constant Pool(SCP) in Java
https://www.geeksforgeeks.org/string-constant-pool-in-java/
240
How to use Mutable class in Java
https://www.javatpoint.com/mutable-class-in-java
241
Difference between hashset and set
https://stackoverflow.com/questions/5139724/whats-the-difference-between-hashset-and-set
242
Difference between List, Set and Map in Java
https://www.geeksforgeeks.org/difference-between-list-set-and-map-in-java/
https://stackoverflow.com/questions/4131655/what-is-the-difference-between-lists-arraylists-maps-hashmaps-collections-et#:~:text=List%20in%20Java%20provides%20ordered,key%20value%20pair%20and%20hashing.
243
Different ways to create objects in Java
https://www.geeksforgeeks.org/different-ways-create-objects-java/
244
Declaring a list field with final keyword
https://stackoverflow.com/questions/13079365/declaring-a-list-field-with-the-final-keyword
245
Create custom arrayList without allowing duplicates
https://youtu.be/FFfJeb8Ec6Y?si=kOIvITPxBhQ75WRJ
246
Why does set not allow duplicates?
https://stackoverflow.com/questions/20870879/why-set-is-not-allowed-duplicate-value-which-kind-of-mechanism-used-behind-them
247
Comparable vs Comparator in Java. When to use?
https://www.geeksforgeeks.org/comparable-vs-comparator-in-java/
248
If a key is null in the HashMap then when is that entry stored in the map?
https://youtu.be/FFfJeb8Ec6Y?si=kOIvITPxBhQ75WRJ
249
How Java 8 Helps in Improving Performance of HashMap?
https://www.geeksforgeeks.org/how-java-8-helps-in-improving-performance-of-hashmap/
250
Tree so in Java. Internal working of tree map
https://www.geeksforgeeks.org/treemap-in-java/
https://www.geeksforgeeks.org/internal-working-of-treemap-in-java/
251
Java Date Time API
https://www.baeldung.com/java-8-date-time-intro
252
Compostable Future in Java
https://www.geeksforgeeks.org/completablefuture-in-java/
253
Functional Interfaces which were there before Java8
https://stevenmwesigwa.com/tutorials/functional-programming-with-streams/13/functional-interfaces-before-java-8#:~:text=There%20were%20plenty%20of%20interfaces,commonly%20used%20in%20multithreaded%20applications.
254
Can we extend one functional Interface from another functional Interface?
https://techwithmaddy.com/java-8-functional-interfaces#:~:text=It's%20used%20to%20ensure%20that,number%20of%20Object%20class%20methods.
255
Drawbacks of using Lambda expressions and closures in Java?
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256
Difference Between map() And flatMap() In Java Stream
https://www.geeksforgeeks.org/difference-between-map-and-flatmap-in-java-stream/
257
Parallel vs Sequential Stream in Java
https://www.geeksforgeeks.org/parallel-vs-sequential-stream-in-java/
258
Future Vs CompletableFuture
https://stackoverflow.com/questions/54359761/future-vs-completablefuture-for-this-use-case-completablefuture-will-make-any
259
How to Determine Java Thread Pool Size
https://dip-mazumder.medium.com/how-to-determine-java-thread-pool-size-a-comprehensive-guide-4f73a4758273#:~:text=Determining%20the%20Number%20of%20Threads%20for%20CPU%2DBound%20Tasks%3A&text=Let's%20say%20you%20have%208,other%20tasks%20and%20system%20processes.
260
What is cyclic dependency? How to get rid of it?
https://stackoverflow.com/questions/3646113/circular-dependency-in-java-constructors
https://stackoverflow.com/questions/55429921/how-to-fix-cyclic-dependency-between-java-modules
https://www.geeksforgeeks.org/circular-dependencies-in-spring/
261
Lazy vs eager loading
https://www.imperva.com/learn/performance/lazy-loading/
https://stackoverflow.com/questions/31366236/lazy-loading-vs-eager-loading
262
https://javasearch.buggybread.com/InterviewQuestions/questionSearch.php?searchOption=label&keyword=Cloning
263
What is Program Counter?
https://www.techtarget.com/whatis/definition/program-counter
