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Introduction to Scala

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List vs ListBuffer

6:27 with andi mitre

A list is another data structure which maintains the order of the elements, allows for duplication and is immutable. Similarly to the ArrayBuffer, the ListBuffer is the mutable form of a list.

New Terms:

List -- A list is an immutable data structure which can contain duplicates and maintains the order if its elements.
ListBuffer -- A ListBuffer is the mutable implementation of a list.

Further Reading:

Lists
ListBuffers
Nil documentation
List documentation & methods
ListBuffer documentation & methods

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    In this video, we learn about lists and list buffers. 0:00
    A list is another data structure which maintains the order of the elements, 0:04
    allow for duplication and is immutable. 0:08
    Similarly to the array buffer, the list buffer is the mutable form of a list, 0:11
    let's dive in and implement some lists. 0:16
    There are a few ways to create a list in Scala. 0:19
    However, the simplest form is by calling the list keyword. 0:22
    Let's jump back into the code and implement some lists. 0:26
    Back into our collections package in our super hero object, we'll clean up 0:30
    everything associated to arrays and array buffers, just for simplicity. 0:34
    Awesome, this creates an immutable list of type string. 0:56
    We can additionally create a list in Scala by using the cons operator noted by colon, 0:59
    colon and the keyword nil at the tail end of the list. 1:06
    By having cons with nil at the end of the statement, 1:18
    creates a list that holds the numbers 1,2,3. 1:21
    Therefore, numbers is a list of integers containing one, two and three. 1:25
    Lists are very fast at retrieving the first and the last element in the list. 1:30
    To get the first element, we call the head method. 1:36
    And for any element besides the first, we can call the tell method. 1:38
    This is probably different from what you may expect in other languages. 1:43
    Let's compile and rerun our app. 1:53
    As expected the immutable heroes that head returns the first element in our list, 2:00
    Wonder Woman. 2:05
    Additionally, the immutable heroes that tale returns everything but 2:06
    the first element. 2:10
    Therefore, a list including Thor, Superman, and Batman. 2:12
    Another neat function which applies to many collections 2:17
    as well as lists is MK string. 2:20
    MK string or Make String can be used to print the elements of a collection as well 2:23
    as it allows you to add a prefix or a suffix to any element when it is printed. 2:28
    In this example, we provide a prefix and our suffix to our immutable heroes list. 2:54
    For each element, we use a comma separator. 2:59
    Let's recompile our app and print out our results. 3:02
    Awesome, similar to how arrays have a mutable array buffer, 3:12
    lists also have a mutable list buffer. 3:16
    To create a list buffer, the mutable form of a list, 3:19
    we need to import it from a Scala collections package. 3:23
    Let’s do so at the top of our file. 3:27
    Importing the package provides us with the flexibility to add, remove or 3:36
    even update our superheroes over time. 3:41
    We can now append to the list buffer by using the append method or 4:01
    simply providing the symbol plus equals. 4:04
    In order to prepend, we would use the plus equals colon symbol. 4:07
    Let's check these out. 4:12
    Let's recompile and run our app. 4:31
    Awesome, we prepended Captain America to our list, and 4:36
    we also append Raven to the end of the list. 4:40
    In order to access an element of the list, we use the parentheses notation. 4:44
    And we provide the index based value. 4:48
    Because list buffers are mutable, we can also update a specific element. 4:58
    Let's remove Thor and replace him with Iron Man. 5:03
    Let's comment out on our print line statements and check out our results. 5:12
    We can remove elements from a list, using the minus equals symbol, or 5:31
    calling the remove method. 5:35
    Additionally, we can remove elements by value or even by index. 5:37
    Let's start by removing an element by value. 5:42
    The tarsal remove an element in mutable heroes by index. 5:51
    Awesome. 6:07
    We get back Wonder Woman, Iron Man, Superman, and Raven which means 6:08
    that we're able to successfully remove Batman and also Captain America. 6:13
    Great, we see how list and list buffers work. 6:18
    In the next video, we will dive into maps and tuples and 6:21
    see how they're useful to our everyday code. 6:25

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