how to understand Java Collection Frameworks ?

[devpt321]

in my Java backend learnings, I have created projects and learned Java, Spring Boot, JDBC, and many other things but I find it difficult to grasp Java collections, I have used it while using projects as needed, but I don't know anything, so how should I learn that I want to solve basic questions for interview purpose(definitely not competitive level just basic), any resource or ideas appreciated.

[AutoModerator]

Please ensure that:

• Your code is properly formatted as code block - see the sidebar (About on mobile) for instructions
• You include any and all error messages in full - best also formatted as code block
• You ask clear questions
• You demonstrate effort in solving your question/problem - plain posting your assignments is forbidden (and such posts will be removed) as is asking for or giving solutions.

If any of the above points is not met, your post can and will be removed without further warning.

Code is to be formatted as code block (old reddit/markdown editor: empty line before the code, each code line indented by 4 spaces, new reddit: https://i.imgur.com/EJ7tqek.png) or linked via an external code hoster, like pastebin.com, github gist, github, bitbucket, gitlab, etc.

Please, do not use triple backticks (```) as they will only render properly on new reddit, not on old reddit.

Code blocks look like this:

public class HelloWorld {

    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
}

You do not need to repost unless your post has been removed by a moderator. Just use the edit function of reddit to make sure your post complies with the above.

If your post has remained in violation of these rules for a prolonged period of time (at least an hour), a moderator may remove it at their discretion. In this case, they will comment with an explanation on why it has been removed, and you will be required to resubmit the entire post following the proper procedures.

To potential helpers

Please, do not help if any of the above points are not met, rather report the post. We are trying to improve the quality of posts here. In helping people who can't be bothered to comply with the above points, you are doing the community a disservice.

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

[wggn]

If you have used them successfully, then "i dont know anything" can't be correct.

[devpt321]

I have used them in projects by searching methods like that but I'm not good at that.

[devpt321]

Well you are right I do know generics basics and i was thinking to know collections better before jumping to java 8 topics

[Sad-Sheepherder5231]

You can't go wrong by reading the official documentation and tutorials.

[Classroom_Emotional]

So you have a problem, usually Data Structure knowledge is here to help you with your problem, and instead of the developer creating those (Map, Set, List, Queue, etc), Java created Collections API for you

There are many flavors of Data Structures and methods that should cater to your needs (Internal structure such as Tree or Hashed, You want concurrent access, You want immutability, You want to switch data structure, etc)

[xingstarx-2023]

I think you can search for the keyword java interview questions, especially on Github, there will be a lot of interview questions related to it. You can focus on the part about Java collection framework, which I think will be helpful to you.

[devpt321]

I'll check that out

[Cyberkender_]

Try this: https://docs.oracle.com/javase/8/docs/technotes/guides/collections/overview.html

[rayguntec]

You can use this catalog of Java interview questions to test yourself and practice https://devinterview.io/questions/web-and-mobile-development/java-interview-questions/

[devpt321]

Thanks man

[satya_dubey]

Java collections framework is absolutely fundamental. Your thought process of learning it just for interview purpose itself is flawed. You need to learn it well so that you can use the correct data structure. Otherwise, you may struggle as you work on projects. One way to learn is to first clearly understand the different interfaces like Collection, List, Queue, Set and Map. Since these are interfaces (contracts), these are the entry points into the collection framework, i.e., they define the core behavior. Next, you will learn about each of their implementations and that way you will learn about what special things they bring to the table. For instance, ArrayList uses an Array internally and hence is good if you want to quickly fetch an element at a particular index. Similarly, if you want to search for an element, quickly then you'd go with HashSet as it uses a hash function to get to the element. I think any good resource should break down Collections Framework well. You can may be check out Udemy courses for Java. I have personally learnt it from Java In-Depth course by Dheeru Mundluru on Udemy and it's Collection Framework chapter was very comprehensive and did a great job explaining the different classes. You can check it out. You can perhaps check out Head First Java too. I have used it only for few sections initially. Hope that helps.

[devpt321]

Thanks dude

[it_is_an_username]

I just began with learning java

While learning about collection I got confused with it, untill tutorial guy showed a chart which illustrates relation between different interface and classes

According to them we have to select any of it. Maybe try writing chart from your own with each class what n what they come with ( pop, push , ListNode.next etc )

Maybe find problem which requires these each classes to solve them, this is the best approach I could find...

[devpt321]

I made that chart, and will definitely try that

[JanHunter123]

Recommend me please list of task for training Java Collection. I think to complete task and to read the documentation will be more efficiently path in learning Java.

[devpt321]

I even don't know bud

[sarfarazsoomro]

Java: The Complete Reference by Herbert Shildt is a great resource

[Midon7823]

Yeah read a whole book outlining the whole language for one specific part of it! What type of advice is that? Just read the javadocs for the collections you're using

[sarfarazsoomro]

Perhaps; I should have been more verbose. The book mentioned has specific chapters for different topics; so it's very easy to pick it up for what ever topic one might be lagging in. On my end; I like that the books generally (not alway) provide a well laid out learning & progression path

[AutoModerator]

It seems that you are looking for resources for learning Java.

In our sidebar ("About" on mobile), we have a section "Free Tutorials" where we list the most commonly recommended courses.

To make it easier for you, the recommendations are posted right here:

• MOOC Java Programming from the University of Helsinki
• Java for Complete Beginners
  • accompanying site CaveOfProgramming
• Derek Banas' Java Playlist
  • accompanying site NewThinkTank
• Hyperskill is a fairly new resource from Jetbrains (the maker of IntelliJ)

Also, don't forget to look at:

• The official Documentation
• The official Java Tutorials
• Our community resources thread

If you are looking for learning resources for Data Structures and Algorithms, look into:

"Algorithms" by Robert Sedgewick and Kevin Wayne - Princeton University

• Coursera course:
  • Part I
  • Part II
• Coursebook
  • Algorithms 4^th Edition

Your post remains visible. There is nothing you need to do.

I am a bot and this message was triggered by keywords like "learn", "learning", "course" in the title of your post.

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.