Android Application Development Tutorial - 16 - Activity Life Cycle Video Lecture | Android Application Development (Mobile App) - Software Development

what's going on guys welcome your 16th
Android tutorial and you know I've
realized that you guys have matured
quite a bit in the Android world over
the past 15 tutorials I think it's about
time to tell you guys about the
lifecycle of the activity class and such
an idiot
all right what we're gonna do is talk
about the lifecycle with activity class
like I said because what happens now is
we had our application run but still our
splash screen is there if we hit the
back button it's gonna go back to our
splash activity and we don't want that
because you know we want a splash
activity to basically kill itself after
it's been been been displayed for the
most part because it's taking up some
memory or it potentially could take up
some memory so we're gonna free up some
of that memory for the most part and
that brings us to the lifecycle of an
activity now I looked up the Android
developer page this is a great resource
for you guys to use just search activity
and it'll go to the lifecycle of the
activity that's where you guys can find
this I'm just gonna talk through kind of
the life cycle and which methods are
important for the most part so here's
what happens an activity starts our
splash screen for example starts then it
calls this oncreate method that's where
we set up our thread and we set up our
layout or set content view we set up
some of all that all of those type of
variables and then it also calls on
start method after after it calls on
create method then it calls on resume
method then our activity actually starts
running that's when the user can touch
the buttons that we have set up and
interact with our activity see it has to
call all three of those methods before
activity actually starts now if our
activity's running and we get a text
message or for example if our splash
activity starts a new activity the
splash activity is going to go through
an on pause and basically go through
when it's not no longer visible it's
gonna go through call an on stop method
or yeah so basically uh basically the
most important one is the on pause but
if our activity gets shut down it's
gonna call the on pause on stop and on
destroy so for example if you guys are
creating a game and the person gets a
text message right in the middle of the
game you might want to have you know a
method or some setting up some variables
or some methods that will save the data
within on pause method because it will
call that on pause method before
anything else happens so that's kind of
a kind of the way that you want to think
about it is you can set up some last
minute or save points or something
within this on create method or on I'm
sorry on within this on pause method and
then once our activity gets started back
up its gonna go through this on resume
method again before it starts running so
the only method that from our activity
class that we are familiar with this is
on create method but we're gonna kind of
use some of these other methods as well
but what I want to show you guys are
sorry if we can kind of ahead of myself
here what I want to show you guys is
that we're gonna use this on create
method but the only other two methods
are really important for the most part
is this on pause method and this on
resume method because even if our
activity gets destroyed it's gonna go
through this on pause method before it
goes through these methods as well so we
might as well set up everything within
this on pause method and we won't have
to worry about these and also the on
resume method we can set up some of our
resume methods or variables that we need
to set up before activity activity
starts again so those are going to be
the three basic methods that we're going
to use for activities in the future but
as for our splash activity we're gonna
get into that right now so open up your
splash activity and hit enter right here
so we only have one bracket left this is
for a whole class this one is for our
starting method and again we're just
gonna right click go down to source
override implement methods and again
through the activity tab we can find the
method called on pause
so this is where we're gonna kind of
make our splash activity kill itself so
to say because we're just evil like that
so the way we can do that is hit finish
it's just a simple method and it's
basically gonna finish the splash
activity get rid of it and it's gonna be
gone forever for the most part until our
user starts up our activity or
application again so pretty simple but
what again is happening is we when this
splash activity starts because it's
launcher item it's gonna go through this
oncreate method that's gonna run and
then basically what happens is when we
call this start activity right here the
splash activity is gonna call this on
pause method because it's going behind
the starting-point activity that's being
created so it's gonna call this on pause
method real quick and that's where we're
just gonna finish our class so we're
gonna say hey destroy yourself finish
yourself and hopefully that made sense
and you guys kind of get the structure
of how the life cycle works for the most
part and and kind of what these methods
mean because I haven't really explained
with on create method is for the most
part so hopefully you guys like that
tutorial and have a little bit better
understanding of the activity class and
how that works so thanks again for
watching I hope you have a good day