#10.4 Kotlin Android Tutorial SET and HASH SET Mutable and Immutable Collections

hi this is drinks with the heart and
welcome to the next video of this
collection module now in this video we
will check out what are immutable set
and mutable set so first of all let us
start with the immutable set by using
the set of keyword so here insert the
IntelliJ IDE let me modify my code so
here I have simply written to comment
line the set contains the unique
elements the hash shed also contains the
unique elements but the sequence is not
guaranteed in the output right now let
me explain you what is a set first so to
define a set or in simple words the
immutable set you can simply use where
or well my set equal to let us say set
of keyword this set contains the list of
objects it simply expects a template let
us have a set of elements of the integer
type and inside this you have to simply
define the values let's say 250 for 3
when 0 and let's say 9 9 and 9 again at
last 8 this set of method actually
returns immutable set that can only
support the read only operation and
currently I have only these set of
elements that is the integer values so
if you want to insert the string values
then simply give the type as string and
similarly simply give the type as float
if you want the fluid values but as of
now I want the integer values for this
demo video right now since this is
immutable in nature so we cannot modify
the my set later on that is you cannot
insert more elements to it you can only
perform the operations such as size
stream contains and so on you cannot add
or remove the elements now to print out
the elements from this my set we need to
use the for loop and the print line
statement so for this the codes are very
simple I will simply use element or any
other variable you want in keyword my
set and now inside this let us print out
the elements such as element
and remove this older comment and now we
are good to go
let us now run the code so in the output
console we can see some weird output
initially 250 4 3 1 & 0 are ok but after
this we have only 9 here but while
inserting the elements we had 3 9
instead of 1 right so how come these two
are getting removed from the set now
initially I told you the sets contain
the unique elements so no matter how
many elements of the values of 9 you
insert it will automatically be removed
from the set because it is the property
of the set that it can only contain the
unique elements so the redundant
elements will be removed and no
duplicate elements will be present right
so that is why we say that sets only
contain the unique elements now suppose
you want to modify your set so for that
you need to use the mutable set now
again we need to change this set of 2
let's say new table set of integer
values right so this will simply return
a mutable set which simply means that
later on you can again modify your set
such as my set dot remove any element
such as I want to remove this 54 so I
will simply use 54 here and then run the
code it will simply strike out the
element of 54 from our set and now the
54 is now gone so that is why we say
that this mutable set of returns the
mutable set right and we can perform the
read and write operation booth now later
on if you want to add some element so we
can simply use my set dot add and simply
add let's say 100 and run the code so in
the output we have 100 as a last element
now this mutable set of actually returns
the set object right now what about this
now what about this hash set so for this
let me show you one more example so
instead of mutable set of you can simply
use hash set off now this will simply
return the object of hash set now if you
are from a Java background then you must
be knowing what this hash set
stands for it also contains the unique
elements but the only difference between
hash set and set is that in the hash set
the sequence is not guaranteed in the
output which means that suppose I have
250 for 3 and so on like this still and
right but for this set it will simply
print out the values in the sequence but
for the hash set the sequence does not
matter and it does not guarantees that
the elements will be printed in the same
sequence so as of now let us check out
what happens in the output consoled so
for this also let us comment out remove
and add operation let us now run the
code and let's see if the elements are
being printed in the sequence or not so
here you can notice I have 0 1 2 3 54 8
& 9 the elements are not being printed
in the sequence because the zero which
is being printed as a first element it
is actually present in the middle of our
hash set and also this 9 is actually
printed at the end but it is present at
the second last element so the sequence
in case of hash set is not guaranteed
but in case of set it is actually
guaranteed so the only difference
between the immutable set of and hash
set of is this only of the sequence so
you can use either of these two as per
your requirement both are mutable set
and both supports read and write
operation that is you can remove element
add element replace any element and so
on so finally we have reached the end of
this module so in this module we talked
about the collections collections and
collections and also we talked about the
immutable collection and mutable
collection in all the cases of list map
and state now if you remember all these
methods such as list of math off and set
off and all these methods that I have
mentioned here are a list of hash map of
and so on you will face no difficulty
for the data structure in Kotlin so make
sure you remember the differences
between the immutable and mutable
collections and the respective methods
of list map and set so this is showing
2/3 signing off and thanks of
and have a good day thank you