Learn Core Java

Online Tutorial for Java beginners to learn basic concepts of Core Java. I have divided this tutorial into three sections. First you will learn the fundamentals of Core Java (Class ,Interface etc.) . In the next section Learn By Example you will find many examples for different Core Java modules with running source code. The third part Cheatsheet will help you quickly revise what you learnt in the first two sections.

  • Getting Started with Java

    Introductory Chapter for complete beginner of Java. You will learn to start working in Java by installing and running and test java application. Along with knowing difference between JDK, JRE and JVM.

  • Java Variables

    Variables are one of two things which in combination create class, most important part of Java. You will learn about different type of Variables and how they can be used or accessed.

  • Java Operators

    You will learn about Operators used in Java. What is precedence and associativity of every Operator.

  • Java Statement

    Java provided different types of Statement. Conditional or assignment. What are the purpose of different type of statement and how they can be used will be defined here.

  • Access Modifier

    This is how you define access levels for different thing in java. Be it Class / Variables / Method. Who and how it can be accessed from different part of Java world.

  • Non Access Modifier

    Java Provided some modifier which doesnt control accessibility but can change the behaviour of particular CLASS / Method / Variable. Theses are called Non Access Modifier. In this chapter you will learn about the same.

  • Class & Object

    In Object Oriented programming Class is the most fundamental thing. In this chapter you will get to know about Classes and Their Objects.

  • Constructor

    In order to create Object from a class definition you will require constructor. How to initialize different variable or how to invoke constructor will be learned here.

  • this keyword

    To refer current executing object this keyword will be used. How to use it will be learned here.

  • Static keyword

    Class level variable or Method can be defined using Static keyword. This chapter will define it.

  • Interface

    It defines the contract between different party that needs to be obeyed. You will learn about Interfaces and their different rules here.

  • Overloading

    To provide different functionality with same method name overloading can be used. How to use this feature in Java will be covered in this chapter.

  • Overriding

    To provide different functionality for different classes in same hierarchy overriding can be used. This chapter will cover different aspect of it.

  • Exception

    In section of Java can throw exception. Here you will learn about different type of exception and how to handle it.

  • Collection

    Collection and their different implementation will be discussed here.

  • Inner Class

    Classes can be declared in class which is known as Inner class.

  • Inheritance

  • String Builder

  • String

    Most used class in java. Which is Immutable. How to achieve this immutability and how to create one immutable class.

  • Serialization
  • Thread

  • Array

     


52 Comments

  • cool section! here’s some more:

    1) Junior java developer
    a) Basic ocjp (former scjp) questions:
    – What does static, final mean, purposes;
    – How many accesibility modifiers exist? Please describe them.
    – Why do you need a main method?
    – How many constructors can you have?
    – Define overwriting and overloading
    – Give java API implementations for overwriting and overloading
    – Describe the String class – unique properties
    – StringBuilder vs StringBuffer
    – Collections : please describe, give some examples and compare them to eachother
    – ArrayList vs Vector
    – HashMap vs HashTable
    – What’s a tree
    – What’s a map
    – Multithreading: describe the management in java
    – What’s a semaphone?
    – How many states are there for threads?
    – Describe the usage for synchronized word (2)
    – Serialization in java – a descrition and usage
    – Garbage collection in java – description and usage
    – Can you guarantee the garbage collection process?
    b) Simple design pattern questions:
    – Singleton please describe main features and coding
    – Factory please describe main features and coding
    – Have you used others? please describe them

    2) Intermediate and Senior level – depending on rate of good responses, additional questions to 1):

    http://centraladvisor.com/programming-2/java/java-developer-interview

  • i need core java and j2EE full tutorial materials. can you send my email? PLEASE friends help me…..

    • Hi Sheetal,

      I am sorry but i can not help you in this regard. This site is collection of my own experiences. I developed this site just for my reference. But eventually it became famous.
      I do not have any consolidated material.

      You have to go through Article by Article only.

      Thanks

    • Hi Gaurav,

      Package is used for organizing classes. This is not something which is enforced by JVM or Java. But it is suggested to have classes defined in proper package coz in that case you can have unique namespace for different classes(even if class name is same.)

      e.g.
      Suppose you and your colleague is working on different modules(Sales and HR ) of the same project and you both are unware of the class name created by other. In the end you might face a situation where both of you have created class with same name(Department). This will create problem. To avoid this problem you both can use package. You can create class in your specific package(com.sales & com.hr). In this way you will avoid conflict of class name. Coz even if class name is same namespace will be unique.

      com.sales.department
      com.hr.department

      hope now you understand the use of package.

    • Hi Ayushi,

      I don’t know what is the purpose of creating this project. But i have one project in my mind because of requirement. So i ll tell you. Try to build it and if successful let me know i might use it.

      We have team of developer where Team Lead assign a work to every one on everyday or weekly basis. and every one in the team has to report to team leader. And leader will analyses in the end what different resources has done in last week or month and generate the report accordingly which will be used in Audit purpose.

      So you will have a web application. It will have two User roles.
      1- Team Lead
      2- Developer

      Roles of Developer
      1- Can view the assigned work by team lead.
      2- Can update the work sheet
      3- Can close the work assigned which in return go back to team lead pool

      Roles assigned to TL role
      1- Can create work
      2- Can assign work created to different user(Developer)
      3- Provide the deadline for different work.
      4- Can generate the report of all work done by developer.

      System functionality.
      1- Once there is any work assigned to any developer mail should be delivered to developer.
      2- When deadline is about to read notification should also reach.
      3- Once developer mark and work as completed. Work should go into TL pool.
      4- Report should be generate in the form of DOC/ Excel

      It is the requirement below the technology stack that you can use
      1- Spring 3.1
      2- Hibernate (Data Persistence)
      3- Spring Security (Role related assignment)
      4- Apache POI (Report Generation)

      I think now i have given you enough information. If you like you can create it. If successful let me know i will glad to add it in my website.

      If you require any more input you can contact me.

      Thanks

  • Hi Gautam,
    Even i was in need of one project for my practice. I will try to implement for ur requirements. If done, i ll let you know… Hope i may take bit long time as this is my first project for which i am working for and i am sure i ll learn more if i implement it.

    Thank you….

    • Hi Brany,

      Best of luck for this project. I would love to know the progress of this project development. If you can successfully implement this do let me know so that i can add the same on website. So that others can take the help of it. You can also write an article for the same.

      Thanks

  • Thank u Gautam, Surely i ll let you know abt my progress… I have not yet started.. Once i start, i ll intimate you…

  • Great description of topics…I have read many topics here all are very good….For knowing internal mechanism of java methods, class and objects please visitjava by vikas

  • Hi,,
    I am new in coding and i want to learn Core Java & C please help me out.

    Thanks Admin

    Please do reply.

    • Hi Vivek,

      As you can see i have different topics for different section in Java. You can start learning Java by following Java article sequentially. I do not have any idea of C++ language. So i would not be able to help you in this regard.

      I would suggest you to first buy a good book for the same. Or if you want more clarity then you can refer original document of Java.

      Thanks

  • Hi Gautam

    Excellent work done .Really helpful for freshers and some times for experienced people too.
    great job and keep it up.

    If possible provide some sample codes to practice with solutions.

    • Hi Ankan,

      Thanks for your nice word. I would love to add more content if time permit.
      I will take your suggestion and try to add more example.

      Thanks

  • i need core java and j2EE full tutorial materials. can you send my email? PLEASE friends help me…..

  • Hi Gautham,

    Thanks for such a nice tutorial… :)
    I am learning java and know core java concepts, but when it comes to write some programs,
    i am feeling difficulty…
    Please let me know the best way to feel it easy and become expert…

    Thanks in Advance

    Regards,
    Chandu

    • Hi Chandra,

      Thanks for your nice comment. If you know the basics then you should not have any problem with writting code. If you want to start coding then you should start with very basics ofcore java like prinitng any value on console. I would suggest you to download Eclipse IDE first.

      I have written different article on how to create Java Project in Eclipse. Once created you can start creating Classes and start playing with same. You can have different assignment available which you can try to solve on your own. Keep in mind that there is no hard and fast rule to learn Java. Only practice can make you perfect.
      While writting code you have specific question you can ask me personally.

      I have a paid service where i use to check the assignment and help learner write code. If you are willing to pay for this let me know.

      Thanks

  • Hi Gautham,

    Thanks for very quick reply…
    Ya i am already using Eclipse IDE and doing small programs, But still feeling difficulty in writing big programs… please help me out…
    and about your paid service, please tell me the clear details like what and all contents you will cover,fee details, etc

    Thanks,
    Chandra

  • Hi Gautham,

    Thanks for the quick reply… :)
    I am using Eclipse IDE for doing Java programs
    i know the core java concepts but progrmaming making me difficult…
    Not able to get confidence on especially Programming…

    and please tell me clear details about your paid service..
    like what and all topics you cover?? Fees??

    Thanks,
    Chandra

  • Hi Gautham Sir,

    Can you teach me core java on online? if so whats the charges ? I really want to take classes from you.

    Please email me asap with positive response.

  • i need core java and j2EE full tutorial materials. can you send my email? PLEASE help me…..sunilcp47@gmail.com

  • Hi core java learned my college life. now am moving advance java. its how many module there? it is also based on the corejava concept?

  • sir , i am student of class 12 and i.p is my additional subject. I am very much confused in coding specially loop statements .. can you please help me.

  • hi….. i am the core java beginner.. i want to learn core java…. is there any way to learn core java easily and perfectly so.. can u please help me…. n also want materils

    • Hi Prabhakar,

      You are already on a page where you will get link to all article which will be required by you to learn Core Java. Have you visited them? And what exactly do you want?
      Also PDF file is already available which you can buy by paying 100 rs.

      What else you are looking for do let me know. I ll see if i can help you in that regard.

      Regards

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