Java Video Tutorial 11

In this part of my Java Video Tutorial I introduce Java collection classes. Specifically I cover how to use Java ArrayLists.

Java ArrayLists make it easy to keep track of groups of objects. A Java ArrayList differs from a java array in that it automatically resizes itself when you add or remove values.

I'll go over nearly every Java ArrayList method in this video.

[derekbanas]

Thank you :) I started programming when my neighbor threw out a TRS-80. My first language was Basic. I then moved on to Assembly and Pascal. I started C++ when I was about 15. It is funny because my family used to tell me I was wasting my life on that silly toy. The funny thing is that almost nobody in my family can still use a computer. I was brought up on a farm in the middle of nowhere

[Tggfredcsawsdfgbhhhhu]

I've watched a lot of java videos on youtube. But yours are by far (judging by this video alone) the most professional and helpful and informative videos. Thank you very very much!

[derekbanas]

I have never found the need to force myself to memorize class or method names. I just use the online api until I naturally just remember the classes I use the most. Code completion in the IDE helps a lot as well.

[derekbanas]

Normally you'll use arrays for collections of primitives. ArrayLists and the other collections have extra overhead, so that is the reason people use arrays for primitives.

[derekbanas]

You are correct. I was just demonstrating everything you can do with an arraylist like a video api. Sorry if that was confusing. I cover arraylists further in this tutorial

[Spacebirdy]

You just saved my day! I wasted 10 hours trying to find out why I'm getting a damn NullPointer until this video that I noticed that I forgot to make it an instance. Now I can finally continue working on the complexity of adding and replacing files to jars or zips.

[derekbanas]

You can use the Iterator with any collection. In my next tutorial on the Iterator Design Pattern you can see that used in a real world example :) I'll try to get it up today

[derekbanas]

I'm very happy to help and to remain free. Hopefully some day more people will cover all of the other topics I don't and everyone can get a free education online :)

[derekbanas]

Thank you :) Please clarify your question. As the tutorial continues I store many different types of objects in ArrayLists. Most everything in java is an object.

[derekbanas]

Don't thank me till you see it :) It is an advanced tutorial. At this point I'm basically providing people with the knowledge a software engineer gets in college and maybe even graduate school. Hopefully that doesn't alienate all of my subscribers

[derekbanas]

public URL getResource(String name) is definitely what you need. Look for it in the java api. Make sure you store the txt file in src or a subfolder of src.

You can also do this
JarFile jarFile = new JarFile("YourJarFile")
JarEntry entry =
InputStream stream = jarFile.getInputStream(entry)

[eesaaphilips]

It's 2017 and i still refer to this tutorial. Great videos...

[derekbanas]

You're right about addAll. toArray returns an array

[derekbanas]

I cover ArrayLists and other topics over and over throughout this tutorial. Feel free to bounce around. If you don't quite get a video skip ahead. I do my best to explain everything each time even if I have covered that topic in the past. Have fun with it and always feel free to ask questions

[fabi]

This man is the best Java instructor I've seen on whole YouTube so far. Fast-paced, comprehensive and ambitious. Keep it up! *opening Eclipse*

[derekbanas]

Don't try to memorize everything. That will just frustrate you. When I was learning, I organized everything into a folder. I had a String folder, that contained all of the String methods and common uses. I had the same for every other core tool. The when I needed something, I'd refer to those files (that were heavily commented) and just copy and paste the code. That's what I try to do with the code on my site. After a while you just remember stuff

[derekbanas]

@supprof1 Thank you for taking the time to watch them. I also appreciate it when you say hi :)

[derekbanas]

The reason it failed is because there are 3 items in indexes 0, 1, 2. Then I use remove to get rid of one and then when removeRange is called it doesn't work. When I make these tutorials I often throw everything possible into them. If I don't run something, that just means it is there for you to experiment with. I'm sorry about the confusion

[derekbanas]

If you don't need the power provided by an arraylists methods stick with arrays or one of the other data structures

[derekbanas]

Yes an ArrayList can store any type of data, but you normally want to store the same data type. As the tutorial continues I cover how to use them in many ways