Arraylist:insertion


#1

why we use insertion? …instead we can erase our array list elements and write them all with the new element we want to insert …or we can type them at the beginning


#2

insertion is very useful, lets say you build an e-commerce website, you need to keep track of the products the user is adding to there shopping cart. Now, lets say the shopping cart is an array, we don’t know up front what the user is going to purchase, so we need insertion.

we can’t just go and say up front: Hey, i wanted to define an array with data upfront, so here are the products you are going to buy

sometimes, the lessons teach concepts, which can be really useful, although maybe its difficult to see straight away.


#3

until now i dont understand where and when i will apply the concepts um learning
… but to some extent i understand wat you said:slightly_smiling_face:


#4

codecademy teaches mostly concepts, but in order to build an application like an e-commerce website (webshop) you will first need to learn the underlying concepts (like an array + insertion to keep track of purchased products by users of your website)

codecademy has free-form projects in which you can implement things, but this is part of pro-subscription ($20/month) but you can also attempt to build things yourself.


#5

can you tell me …whats the sort of programs or things in my pc …that enable me to build a prgram or website


#6

so far, what have you written in the lessons? Only text, right? so any text-editor will do to write many languages (java, python, ruby, html & css and so on). You could go with a general text-editor like atom

however, for java, ruby and python we need to install a program which can run the code you have written.

here is a good point to start:

http://www.oracle.com/technetwork/java/javase/downloads/index.html

for java, you also might consider an IDE to make life easier (like eclipse or netbeans)


#7

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