Important topics in core java for exam and interview

Important topics in core java for exam and interview

Are you the one who has decided to learn java but don’t know

  • where to start?
  • what java books to follow?
  • about important topics to cover in java
  • about online free materials for learning java
  • about online paid courses

This article is going to help you with everything that you need to know to head start your java journey from beginner to professional. 


Here we will tell about

  • the important or main topics to learn in core java
  • java books to follow, 
  • java online free courses, 
  • java online paid courses

Our first move should be to learn the important topics in java that will be helpful in building practical projects.

Important topics in core java

Given below are the java important topics that you should cover to get well acquainted and begin working on java technologies. As a beginner your main focus should be to clear the basics concepts related to these topics.


You can learn all the topics here - java tutorial by tutorialsinhand

Basic of java

  • class and objects
  • java data types,
  • java variables (class variable, instance variable, local variable, parameter variables)
  • why java is platform independence?
  • jdk, jre, jvm, 
  • bytecode, path, classpath
  • public static void main(String[] args) → Explain the significance of each words in it.
  • java method
  • java constructor
  • java program internal working
  • java vs javac command
  • Also learn few basic programs (click the link for programs)

Decision making statements 

Loop controls 

Object Oriented Programming concepts

  • Polymorphism → Overloading and Overriding
  • Encapsulation → How to achieve encapsulation?
  • Abstraction → Ways to achieve partial and complete abstraction using abstract class/interface
  • Inheritance → Different types of inheritance
  • Why multiple inheritance not supported by java classes?

Java Strings

  • ways to create string objects
  • why string is immutable?
  • == vs equals
  • string buffer, string builder and their difference
  • split method, String tokenizer
  • various methods of String like length, substring, concat, tochararray, toupper, tolower, etc.


Collection interface and classes

  • Lists like Arraylist, Linkedlist, Vector and difference between them
  • Sets like Hashset, LinkedHashSet, TreeSet and differences between them
  • Maps like HashMap, LinkedHashMap, TreeMap and differences between them
  • List vs Set vs Map
  • Collection vs Collections
  • Hashtable and hashing technique
  • hashcode and equals contract
  • using different Collection, storing elements in them, fetching elements, sorting  and searching elements.

Generics in java

  • advantages of using generics
  • How to use generics in java program?

Exception Handling mechanism

  • exception vs error
  • exception hierarchy and what is parent class of all exception
  • try-catch
  • finally
  • correct sequential order of java try with multiple catch and a finally
  • checked vs unchecked exception
  • throw, throws and their difference
  • custom exception

Multithreading concepts

  • ways of creating java thread
  • thread life cycle
  • methods like sleep, wait, notify, notifyall
  • synchronization
  • deadlock

Date-time concepts in java


  • Establishing jdbc connection
  • different statements like statement, prepared statement, callable statement

Important keywords

  • super,
  • this,
  • final,
  • finally,
  • finalize,
  • static

Online free tutorial:

All the important topics of java is explained in our java tutorial. We have designed this course to deliver best knowledge on java. Explore it now

  1. java tutorial by tutorialsinhand

Java Books to follow:

If you are beginning to learn java, then the below books would be better for you (choose any one to begin with):

  1. Computer Science with Java by Sumita Arora - Get it now(preferred for school students of XII)  
  2. Java: The Complete reference by Herbert Schildt - Get it Now (I studied this book in college during my B.Tech Course and its good one to start with.)
  3. Head First Java : A brain friendly guide -Get it now (This is a book from best house Head First. I personally like almost every book of Head First. Reason being the way they explain the things using images and increased interactiveness keeps the reader engaged and doesn't let you get bored)
  4. Programming with Java by Balagurusamy - Get it now (This one is for one who wants to learn java in simple language.)
  5. Let us Java by Yeshvant Kanetkar - Get it now (Again a book for the one who wants to learn java in simple language.)
  6. Introduction to java by Sedgewick - Get it now
  7. Core java volume - 1 fundamentals by Cay S Horstmann - Get it now

If you have basic knowledge in java and you desire to polish it to become expert then follow:

  1. Effective Java by Joshua Baloch - Get it now
  2. Java programming interviews exposed (WROX) by Noel Markham - Get it now
  3. Java Concurrency in practice 1/e Goetz - Get it now


OCJP Certification Books:

  1. SCJP java SE 6 by Kathy Sierra - Get it now (This one is the best books to help you enhance your knowledge from intermediate to Expert level. I have got this book 4 years ago. Still study it. Best for those willing to prepare for OCJP certification.)
  2. OCA/OCP Java SE 7 Programmer 1 & 2 by Kathy Sierra  - Get it now (Haven't studied it yet but is the enhanced version of previous one.Java SE 7 is for Java SE 7 OCJP Certification)
  3. OCA Java SE 8 Programmer I Exam Guide by Kathy Sierra and Bert Bates - Get it now(Haven't studied it yet but is the enhanced version of previous one.Java SE 8 is for Java SE 8 OCJP Certification)

OCJP stands for Oracle Java Certified Programmer. Earlier this test was conducted as SCJP (Sun certified jva programmer)

The certification exam is now conducted for two level:

  • OCAJP (Beginner level)
  • OCPJP (Advanced level)

All the books mentioned above have been filtered out from the vast pool of available books. 


The one which is read by author of this article is mentioned in the ( ).

Have tried to help the readers with best java book knowledge that I have.

Choice is all yours to choose the one that you like from above list. In case you are not satisfied with above list, we would encourage you to explore, google or ask from your peers to know what they are reading to learn java.


Hope this article helps you.


Thank you for reading and investing your time.

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About the Author
Rohanjit Kumar
Technology geek, loves to write and share knowledge with the world. Having 9+ years of IT experience. B.Tech in Computer Science & Engineering
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