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Trying to come up with the simplest way to create binary tree, so i read alot of code online from different sources.
how is it theres so many different ways to create a working binary tree? This is what i dont understand about programming syntax/language... the logic i get.. but i believe there should be a set , uniform foundation to create the same things in the simplest way. Am I wrong?
create tree
create node
create node root
Ok,
I will try to answer your question.
Let's take a big box. You want to put inside some things. Few days after, you will have to find something and use it. Someday, maybe you will want to throw something away.
So, what is your approach, if you are sure, that you will never use any object of them? Probably you will not care where and how you put this object. It is fast and easy to do.
What, if someday, you will want to use some objects? You keep this way and you will be loosing a lot of time for searching or maybe you will try to keep some order inside and easily find an object?
Exactly the same story is with the Binary Trees.
Each of alghoritms has some properties f.e. a lot of algos keep your tree balanced. Before you choose an implementation for your code, think about how you will use it and take a proper one.
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I’m learning Java and have recently started my first project. The idea of this project is to pass one input argument - path to file/folder, which would be analyzed in order to find all files with predefined extension, parse them and create objects based on the results of parsing to store for future.
So far I’ve written all the code and my project structure (simplified) looks like that:
Class defining resulting object
Class that analyzes the input parameter (exists, is file, is folder) and processes it, returning list of all suitable files
Class that parses suitable files and creates objects
The question is - am I following OOP with that structure?
From what I’ve read on the web the last two classes seem to look like polterheists. But I don’t think that it is a good idea to move the logic of the third class to the object class because it consists of lots of methods (define current section of the file, strategy to parse each separate section).
I am learning on my own and don’t want to start my journey by cultivating bad habits.
I am learning on my own and don’t want to start my journey by cultivating bad habits.
You're saying this like you have a choice :)
From what you described it seems reasonable, of course w/o seeing the code we can't say. And even if you show the code - 100 people will have 100 opinions, there's a lot of debates around OOP.
What's important is not to look at your design as something static. Once your app starts to be more complicated you'll have to re-work some of it.
PS: stackoverflow doesn't like this kind of questions since everyone will have an opinion. You'll have to find other resources if you keep having such questions.
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I'm doing my first Mobile App and i have been studying java for about 2 weeks now so i'm pretty new.
The app that i'm trying to make is a grocery list app.
Basically, I want to sort my grocery list by department wise. For example:
Fruit items will go in a fruitArray
the meat items will go in meatArray
etc.
Should I create a single file for each department (Fruit, meat, bakery) or can i store all my array in the same file and access them separately?
I did some search but i cannot find a topic that answers my question.
I would like to know what would be the best way to do it and if it's to put the arrays in the same file, how can i do that ?
Thanks☺
When you're doing or learning something new, do whatever works for you. Consider trying to do both, as it's experience you'll gain for future.
Some general things to take note of though :
Storing all items in one file could potentially create one massive file (regardless of the project you're working on, im generalizing now)
Storing items in different files increases the overhead of having to handle and manage different files.
These are things you will have to consider and things you'll learn from experience, based on the project and various different aspects.
For the sake of this question, I think storing different items in different files would potentially be a better, simpler solution for now, but it really depends on the entire project and how you plan to implement it. Hope this at least somewhat answers your question. Happy coding and happy learning
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I need a hint on an Interview question that I came across. I tried to find a solution but I need advice from experts over here. What are the different strategies you would employ had you came across this particular situation? The question and my thoughts are as follows:
Q. You want to store a huge number of objects in a list in java. The number of objects is very huge and gradually increasing, but you have very limited memory available. How would you do that?
A. I answered by saying that, once the number of elements in the list
get over a certain threshold, I would dump them to a file. I would typically then build cache-like data-structure that would hold the most-frequently or recently added elements. I gave an analogy of page swapping employed by the OS.
Q. But this would involve disk access and it would be slower and affect the execution.
I did not know the solution for this and could not think properly during the interview. I tried to answer as:
A. In this case, I would think of horizontally scaling the system or
adding more RAM.
Immediately after I answered this, my telephonic interview ended. I felt that the interviewer was not happy with the answer. But then, what should have been the answer.
Moreover, I am not curious only about the answer, I would like to learn about different ways with which this can be handled.
Maybe I am not sure but It indicates that somewhat Flyweight Pattern. This is the same pattern which is been used in String pool and its efficient implementation is must Apart from that, we need focus on database related tasks in order to persist the data if the threshold limit is surpassed. Another technique is to serialize it but as you said, the interviewer was not satisfied and wanted some other explanation.
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How to look for a particular object in a large list(java collection) without iterating it. Assume we have a large collection and just need to check whether a object exists or not without iterating.
Ok, Let's step out of the binary world.
Think of a chest full of Lego parts. You want a 2x2 flat black piece.
How would you find it without looking in the chest?
There is no magical to find it, you need to jump into the chest and find the piece grabbing one by one and checking if it's the one you are looking for.
There are ways to speed up the process.
You can Organise (sort your collection) by colour for example and just look in the black pile.
Or you can map (Index your pieces) so you know the position of the piece and can go and retrieve from you know where the piece is.
That is, in a very simplistic way, the same idea for databases and collection.
So, summarizing, no, you can't not just find without looking. Sorry :(
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So I've been giving a project for school and was just hoping for reassurance towards the decision making I do.
My java skills are extremely basic and need to improve drastically soon! I just seem to be getting nowhere atm :P
Anyway, back on topic.
My first task is to create an interface directory that can do the following
Keep in mind this is assessed work therefore please don't provide answers. I have enough time to complete this since I've started early!
My initial approach for going about this task is using a Linked List. I don't know what you guys think about that? I may be completely wrong but based on the topics we have covered in School. LinkedList definitely seems suitable. I can add, get and remove.
Cheers for reading guys!
You are along the right lines. The java.util.Collections package will contain most of what you need.
I would actually use an ArrayList rather than a LinkedList as it is faster for random access and sorting.
However note that it says you should be able to find people efficiently and look them up by name.
That suggests using something like a TreeMap structure, mapping name to a class containing information on each person. Store the names as "Surname, Forename" and they will be sorted correctly.
That will only allow lookups based on the complete and correct name though. If you want to search for partial names the map is less useful.