Java Interview Guide : 200+ Interview Questions and Answers
4.3 (1,876 ratings)
Course Ratings are calculated from individual students’ ratings and a variety of other signals, like age of rating and reliability, to ensure that they reflect course quality fairly and accurately.
11,967 students enrolled

Java Interview Guide : 200+ Interview Questions and Answers

Get Ready for your Java Interview with 200+ Java Interview Questions for Beginners
4.3 (1,876 ratings)
Course Ratings are calculated from individual students’ ratings and a variety of other signals, like age of rating and reliability, to ensure that they reflect course quality fairly and accurately.
11,967 students enrolled
Last updated 10/2018
English
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Current price: $10.00 Original price: $199.99 Discount: 95% off
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This course includes
  • 6 hours on-demand video
  • 2 articles
  • 2 downloadable resources
  • Full lifetime access
  • Access on mobile and TV
  • Certificate of Completion
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What you'll learn
  • You will understand what kind of questions are asked in Beginner Java Interviews
  • You will be able to Answer questions on Java Platform, Wrapper Classes and Strings

  • You will be able to quickly revise all Your Java Concepts with Awesome Examples

  • You will Understand New Features in Java 5, Java 6, Java 7 and Java 8
  • You will Understand Basic and Advanced Object Oriented Concepts
  • You will be able to Answer Questions on Collections, Generics and MultiThreading
  • You will Understand Exception Handling Best Practices
  • You will Understand basics of Functional Programming - Lambda Expressions and Streams
Requirements
  • You have experience with Java
  • In the course, we use Eclipse to demonstrate examples. Some Java IDE will be useful.
Description

How about Quickly Revising all the Important Java Concepts in about 6 Hours before an interview?

Preparing for Java Interview is tricky. You would need to get a good understanding of new features and revise concepts you used in your preparation. This course helps you Prepare for Java Interview with hands-on code examples covering 200+ Java Interview Questions and Answers on varied range of topics listed below. 

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******* Questions Discussed in this Interview Course *******

Java Platform

  • 1 . Why is Java so popular?

  • 2 . What is platform independence?

  • 3 . What is bytecode?

  • 4 . Compare JDK vs JVM vs JRE 

  • 5 . What are the important differences between C++ and Java?

  • 6 . What is the role for a classloader in Java?

Wrapper Classes

  • 7 . What are Wrapper classes?

  • 8 . Why do we need Wrapper classes in Java?

  • 9 . What are the different ways of creating Wrapper class instances?

  • 10 . What are differences in the two ways of creating Wrapper classes?

  • 11 . What is auto boxing?

  • 12 . What are the advantages of auto boxing?

  • 13 . What is casting?

  • 14 . What is implicit casting?

  • 15 . What is explicit casting?

Strings

  • 16 . Are all String’s immutable?

  • 17 . Where are String values stored in memory?

  • 18 . Why should you be careful about String concatenation(+) operator in loops?

  • 19 . How do you solve above problem?

  • 20 . What are differences between String and StringBuffer?

  • 21 . What are differences between StringBuilder and StringBuffer?

  • 22 . Can you give examples of different utility methods in String class?

Object oriented programming basics

  • 23 . What is a class?

  • 24 . What is an object?

  • 25 . What is state of an object?

  • 26 . What is behavior of an object?

  • 27 . What is the super class of every class in Java?

  • 28 . Explain about toString method ?

  • 29 . What is the use of equals method in Java?

  • 30 . What are the important things to consider when implementing equals method?

  • 31 . What is the Hashcode method used for in Java?

  • 32 . Explain inheritance with examples . 

  • 33 . What is method overloading?

  • 34 . What is method overriding?

  • 35 . Can super class reference variable can hold an object of sub class?

  • 36 . Is multiple inheritance allowed in Java?

  • 37 . What is an interface?

  • 38 . How do you define an interface?

  • 39 . How do you implement an interface?

  • 40 . Can you explain a few tricky things about interfaces?

  • 41 . Can you extend an interface?

  • 42 . Can a class extend multiple interfaces?

  • 43 . What is an abstract class?

  • 44 . When do you use an abstract class?

  • 45 . How do you define an abstract method?

  • 46 . Compare abstract class vs interface?

  • 47 . What is a constructor?

  • 48 . What is a default constructor?

  • 49 . Will this code compile?

  • 50 . How do you call a super class constructor from a constructor?

  • 51 . Will this code compile?

  • 52 . What is the use of this()?

  • 53 . Can a constructor be called directly from a method?

  • 54 . Is a super class constructor called even when there is no explicit call from a sub class constructor?

Advanced object oriented concepts

  • 55 . What is polymorphism?

  • 56 . What is the use of instanceof operator in Java?

  • 57 . What is coupling?

  • 58 . What is cohesion?

  • 59 . What is encapsulation?

  • 60 . What is an inner class?

  • 61 . What is a static inner class?

  • 62 . Can you create an inner class inside a method?

  • 63 . What is an anonymous class?

Modifiers

  • 64 . What is default class modifier?

  • 65 . What is private access modifier?

  • 66 . What is default or package access modifier?

  • 67 . What is protected access modifier?

  • 68 . What is public access modifier?

  • 69 . What access types of variables can be accessed from a class in same package?

  • 70 . What access types of variables can be accessed from a class in different package?

  • 71 . What access types of variables can be accessed from a sub class in same package?

  • 72 . What access types of variables can be accessed from a sub class in different package?

  • 73 . What is the use of a final modifier on a class?

  • 74 . What is the use of a final modifier on a method?

  • 75 . What is a final variable?

  • 76 . What is a final argument?

  • 77 . What happens when a variable is marked as volatile?

  • 78 . What is a static variable?

conditions & loops

  • 79 . Why should you always use blocks around if statement?

  • 80 . Guess the output

  • 81 . Guess the output

  • 82 . Guess the output of this switch block . 

  • 83 . Guess the output of this switch block?

  • 84 . Should default be the last case in a switch statement?

  • 85 . Can a switch statement be used around a String

  • 86 . Guess the output of this for loop

  • 87 . What is an enhanced for loop?

  • 88 . What is the output of the for loop below?

  • 89 . What is the output of the program below?

  • 90 . What is the output of the program below?

Exception handling

  • 91 . Why is exception handling important?

  • 92 . What design pattern is used to implement exception handling features in most languages?

  • 93 . What is the need for finally block?

  • 94 . In what scenarios is code in finally not executed?

  • 95 . Will finally be executed in the program below?

  • 96 . Is try without a catch is allowed?

  • 97 . Is try without catch and finally allowed?

  • 98 . Can you explain the hierarchy of exception handling classes?

  • 99 . What is the difference between error and exception?

  • 100 . What is the difference between checked exceptions and unchecked exceptions?

  • 101 . How do you throw an exception from a method?

  • 102 . What happens when you throw a checked exception from a method?

  • 103 . What are the options you have to eliminate compilation errors when handling checked exceptions?

  • 104 . How do you create a custom exception?

  • 105 . How do you handle multiple exception types with same exception handling block?

  • 106 . Can you explain about try with resources?

  • 107 . How does try with resources work?

  • 108 . Can you explain a few exception handling best practices?

Miscellaneous topics

  • 109 . What are the default values in an array?

  • 110 . How do you loop around an array using enhanced for loop?

  • 111 . How do you print the content of an array?

  • 112 . How do you compare two arrays?

  • 113 . What is an enum?

  • 114 . Can you use a switch statement around an enum?

  • 115 . What are variable arguments or varargs?

  • 116 . What are asserts used for?

  • 117 . When should asserts be used?

  • 118 . What is garbage collection?

  • 119 . Can you explain garbage collection with an example?

  • 120 . When is garbage collection run?

  • 121 . What are best practices on garbage collection?

  • 122 . What are initialization blocks?

  • 123 . What is a static initializer?

  • 124 . What is an instance initializer block?

  • 125 . What is tokenizing?

  • 126 . Can you give an example of tokenizing?

  • 127 . What is serialization?

  • 128 . How do you serialize an object using serializable interface?

  • 129 . How do you de-serialize in Java?

  • 130 . What do you do if only parts of the object have to be serialized?

  • 131 . How do you serialize a hierarchy of objects?

  • 132 . Are the constructors in an object invoked when it is de-serialized?

  • 133 . Are the values of static variables stored when an object is serialized?

Collections

  • 134 . Why do we need collections in Java?

  • 135 . What are the important interfaces in the collection hierarchy?

  • 136 . What are the important methods that are declared in the collection interface?

  • 137 . Can you explain briefly about the List interface?

  • 138 . Explain about ArrayList with an example?

  • 139 . Can an ArrayList have duplicate elements?

  • 140 . How do you iterate around an ArrayList using iterator?

  • 141 . How do you sort an ArrayList?

  • 142 . How do you sort elements in an ArrayList using comparable interface?

  • 143 . How do you sort elements in an ArrayList using comparator interface?

  • 144 . What is vector class? How is it different from an ArrayList?

  • 145 . What is linkedList? What interfaces does it implement? How is it different from an ArrayList?

  • 146 . Can you briefly explain about the Set interface?

  • 147 . What are the important interfaces related to the Set interface?

  • 148 . What is the difference between Set and sortedSet interfaces?

  • 149 . Can you give examples of classes that implement the Set interface?

  • 150 . What is a HashSet?

  • 151 . What is a linkedHashSet? How is different from a HashSet?

  • 152 . What is a TreeSet? How is different from a HashSet?

  • 153 . Can you give examples of implementations of navigableSet?

  • 154 . Explain briefly about Queue interface?

  • 155 . What are the important interfaces related to the Queue interface?

  • 156 . Explain about the Deque interface?

  • 157 . Explain the BlockingQueue interface?

  • 158 . What is a priorityQueue?

  • 159 . Can you give example implementations of the BlockingQueue interface?

  • 160 . Can you briefly explain about the Map interface?

  • 161 . What is difference between Map and sortedMap?

  • 162 . What is a HashMap?

  • 163 . What are the different methods in a Hash Map?

  • 164 . What is a TreeMap? How is different from a HashMap?

  • 165 . Can you give an example of implementation of navigableMap interface?

  • 166 . What are the static methods present in the collections class?

Advanced collections

  • 167 . What is the difference between synchronized and concurrent collections in Java?

  • 168 . Explain about the new concurrent collections in Java?

  • 169 . Explain about copyonwrite concurrent collections approach?

  • 170 . What is compareandswap approach?

  • 171 . What is a lock? How is it different from using synchronized approach?

  • 172 . What is initial capacity of a Java collection?

  • 173 . What is load factor?

  • 174 . When does a Java collection throw UnsupportedOperationException?

  • 175 . What is difference between fail-safe and fail-fast iterators?

  • 176 . What are atomic operations in Java?

  • 177 . What is BlockingQueue in Java?

Generics

  • 178 . What are Generics?

  • 179 . Why do we need Generics? Can you give an example of how Generics make a program more flexible?

  • 180 . How do you declare a generic class?

  • 181 . What are the restrictions in using generic type that is declared in a class declaration?

  • 182 . How can we restrict Generics to a subclass of particular class?

  • 183 . How can we restrict Generics to a super class of particular class?

  • 184 . Can you give an example of a generic method?

Multi threading

  • 185 . What is the need for threads in Java?

  • 186 . How do you create a thread?

  • 187 . How do you create a thread by extending thread class?

  • 188 . How do you create a thread by implementing runnable interface?

  • 189 . How do you run a thread in Java?

  • 190 . What are the different states of a thread?

  • 191 . What is priority of a thread? How do you change the priority of a thread?

  • 192 . What is executorservice?

  • 193 . Can you give an example for executorservice?

  • 194 . Explain different ways of creating executor services . 

  • 195 . How do you check whether an executionservice task executed successfully?

  • 196 . What is callable? How do you execute a callable from executionservice?

  • 197 . What is synchronization of threads?

  • 198 . Can you give an example of a synchronized block?

  • 199 . Can a static method be synchronized?

  • 200 . What is the use of join method in threads?

  • 201 . Describe a few other important methods in threads?

  • 202 . What is a deadlock?

  • 203 . What are the important methods in Java for inter-thread communication?

  • 204 . What is the use of wait method?

  • 205 . What is the use of notify method?

  • 206 . What is the use of notifyall method?

  • 207 . Can you write a synchronized program with wait and notify methods?

Functional Programming - Lamdba expressions and Streams

  • 208 . What is functional programming?

  • 209 . Can you give an example of functional programming?

  • 210 . What is a stream?

  • 211 . Explain about streams with an example?

  • what are intermediate operations in streams?

  • 212 . What are terminal operations in streams?

  • 213 . What are method references?

  • 214 . What are lambda expressions?

  • 215 . Can you give an example of lambda expression?

  • 216 . Can you explain the relationship between lambda expression and functional interfaces?

  • 217 . What is a predicate?

  • 218 . What is the functional interface - function?

  • 219 . What is a consumer?

  • 220 . Can you give examples of functional interfaces with multiple arguments?

New Features

  • 221 . What are the new features in Java 5?

  • 222 . What are the new features in Java 6?

  • 223 . What are the new features in Java 7?

  • 224 . What are the new features in Java 8?

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Who this course is for:
  • You are learning Java and want to prepare for a Java Interview
  • You are a Java Beginner and want to test your Java Knowledge
  • Students who want to add more depth to their Java Knowledge
Course content
Expand all 55 lectures 05:54:01
+ Java Platform
4 lectures 15:19
Compare JDK vs JVM vs JRE
04:05
Differences between C++ and Java
02:07
Java Classloaders
04:00
+ Strings
1 lecture 09:46
String, StringBuffer and StringBuilder
09:46
+ Basics of Object Oriented Programming
8 lectures 59:29
Object Basics - Class, Object, State and Behavior
06:35
toString method
03:27
equals and hashCode methods
10:33
Inheritance, Method overloading and Method overriding
11:21
Interface
08:26
Abstract Class
09:59
Constructors - this() and super()
07:25
Do not forget to do Exercises
01:43
+ More Object Oriented Programming Concepts
6 lectures 32:13
Polymorphism and instanceof
08:34
What is Coupling?
05:23
What is Cohesion?
05:00
What is Encapsulation?
04:39
Inner Class and Static Inner Class
05:47
What is an anonymous class?
02:50
+ Modifiers
3 lectures 20:38
Access Modifiers - public, private, protected and default
09:55
Final method, variable and class
03:42
Static variables and methods
07:01
+ Conditions and Loops
1 lecture 08:09
Simple Puzzles on conditions and loops
08:09
+ Exception Handling
4 lectures 32:00
Exception Handling - try, catch and finally
09:10
Checked and Unchecked Exceptions
05:48
Throwing an Exception
05:43
Creating Custom Exceptions
11:19
+ Miscellaneous Topics
6 lectures 31:16
Arrays
05:38
Enum
05:08
Variable Arguments
03:49
Asserts and Garbage Collection
05:24
Static and Member Initializers
04:19
Serialization
06:58