Lecture 26 | Programming Methodology (Stanford)

Lecture by Professor Mehran Sahami for the Stanford Computer Science Department (CS106A). Professor Sahami lectures non-standard Java and shows the class a few books he recommends for further readings on Java.

CS106A is an Introduction to the engineering of computer applications emphasizing modern software engineering principles: object-oriented design, decomposition, encapsulation, abstraction, and testing. Uses the Java programming language. Emphasis is on good programming style and the built-in facilities of the Java language.

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this presentation is delivered by the stanford center for professional

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study questions

about anything we've done so far and last and what you've got and foreign

experts topic

before we dive in particular topic

feeling okay

one of things that we sort of gone the whole time in this class we use these

things called a cm librarians

and they sam libraries are set of libraries contractually created by a

task force people they say the association for community really talked

about them at the very beginning of the christ we talked about these libraries

who put together some nice libraries have stopped at a really useful for

teaching which is actually why we use them

and so today i want to do it left a little bit underneath the hood and talk

a little bit about standard java

which is what you would get if you didn't use the aclu libraries and

you just use the standard java libros now i have no reason why you can't

continue to use the a c white recap of the class

that's another set of libraries that were written by a group of people that

you're certainly welcome to use

so there's no reason why you

should stop using them

but i just want to give you a little bit there's a couple important issues relate

to standard java that now is a time when we can find a lift the covers and it's

time for you to know

so the first thing that's related to thinking about standards outlined

you know when you're running your programs in uganda clips and you do your

you click on the little running guide to compile your programs and then it gives

you a list attention we ob

classes you actually might want to run sometimes if you only have one project

images only get one twice

but i think i think about it a maryland like in the game show for program i

actually have like four or five different classes

how can always knew which class to run acknowledged his name sir for class was

the class and i actually should run

right i had a bunch of classes and their anyone wanna venture a guess

it's only class wounded orion which is barry related to

and underlying issue which is that it's the only class that actually was

extending program

and so wanted extended program what actually was happening underneath the

hood of the atm_ libros is you are getting a method

and maine is actually the place now your total old enough to see main

maine is actually the method at which java classes actually start running

and so i think you should think now as you get a little distributor like and i

never wrote method called me

i never saw a method called main you're telling me that's where java programs

actually start running

yeah in fact it is

and it's because programs

provided this main method for you and with his main method in the program

was essentially get the rest of your program running by getting a few things

set up a ninety cannot cure runner

so you didn't actually need to worry about this

but now you're sort of old enough

to actually see what that means after dissolve about

so if we think about what this means that the guys and though hope for the

main method is also kind of where this part of a reason why we never showed you

the main method before

the head of hair for the main method is actually public

static

poorly

team but we're not done yet me and actually have some arguments

it has been a rehab stream

called pardons

as arguments and then something here happens inside of me

and we showed that you're on the first day we would have to go through and

explain what all these words man

before we explain what main even wise before we explained you how do you

writer first program

that would have been a pain

but now we can just tell you right public means is a public method you know

that if i call the other public methods you've written

static means that this is actually eight

method that belongs to the class

it's it instead it's not something that you would actually call on a particular

object right

so you never have some project like yours mine object action i call acts dot

main

maine is just something that gets called

class method as opposed to being a method that gets called on an instant

and avoid means just returns nothing

what it's getting passed in here is an array of strings you might say it was

that array of strings coming from that's actually harks back to the days of your

when computers weren't all nice in graphical when everything

and when people actually well programs they wrote a program and then they were

typing on what's called the command line they wrote the name of the program out

the actually typed it

and then they typed a bunch of things that they want to be passed into the

program

as sort of like initial information to start that program

though the national thanks hope you had some program like names are for

you might actually start off by giving the name of the program

and then happening separate you might give it some other people think that you

might give the name of the data file

like leader dot correct

anybody given it some other things as well but were separated by spaces

and this list of stop is essentially what gets passed in here is arguments

there just rings

and this is how the program would actually know what came in on what we

refer to as the command line when the program is kicked off a mighty

from our job is not that although the language right exotic came around really

sagging popularity in nineteen ninety five

people aren't doing a lot of nineteen ninety five like i already have like my

mouth and i have my folders and i have all this other stuff

even if you were like six years old

you probably already dead right and you like i never typed this stop

so why do i care about at the reason why you care about is actually java derived

from another language called seat which

and as a variation called c_ plus plus

that was created when people writing programs in the days of your and the

whole notion of maine and having some arguments they get passed to me kind of

came along with sort of the baggage of

actually having a program language becomes the sort of matches the c

stop programming languages when they did do this

so a lot of the times in a row java program these days there aren't really

any argument regarding mister some system parameters something like that

we don't usually worry about them

okay but just so

when you go and look at some other java program is that you can be a scam

library can you see this main thing in your wondering what's it all about

this is you don't think i mean analogously toronto

it's just won't give you know the whole time you've been thinking of running for

your execution starts

maine is really were executions

that you think about

okay execution actually started in maine so how did this thing actually kick off

my runescape

now you're short old enough to see that's you

so what it actually did like let's say this was the main method in a program

like

named surf

so somewhere

inside of eight op program inside the ec and libraries for program we have

this main method

they figured out what the name of your class was essentially it had a one-liner

renewed

that would have been approval incidents

new name surfer

and started

departed

start to wonder why

and now

you know what this means what was actually doing what it means you would

main started note

object exist in the world like at the static method

so there's no object that you're you know giving them a message to your just

main just kind of starts off wakes up says hey i mean what am i going to do

why don't i create

some object of this particular tightening surfer which happens

instantiate an object which is your program

and then remember your program as we can talk about implements the run method and

actually a program underneath the hood

implements the run double interface that we talked about last time remember with

threads we talked about the run a bowl interface

lol programs and plant or animal interface and how you kick off something

that's run double use a start

so what it basically did was created an object of your class which was named

surfer

and told at the start and it happened to start pass along these arguments

but you never needed to see those arguments the matter fact you never did

see them because

when your articles instantiated it didn't expect any arguments

so the argument actually got pass this thing called stock we just ignored them

basically

and then started to run method to kick everything off

and last summer we talked about start we talked about this in the context of

thread so we said hello you create a new thread

and that are the object that you're gonna start running we put inside of

thread we take the thread off with start

in this case we're not actually creating a new thread

we're just saying i want to start executing basically decided that bag is

created it implements run of course they'll start running from the method

run

but i'm not creating a new thread so this thing is going to execute in the

same thread of execution

as the entire

so i don't suddenly kick off something that's running in parallel with this guy

it's actually just sequentially going to start name surfer

and that's the last thing that this guy does which is based on a valuable

sam questions about that

kind of a funky concept but that's basically what's going on you should see

it

we're creating an instance of your program and then just kicking it off

and that's why this whole time we have this thing called the run method that

had to be public

because is implementing the rundle interface but now you've seen any

and the only reason you know you kind of mca

added meaning your program to begin with and include all the score the only

reason we didn't put it in there before

it because will want to planing to stop

in week two of the class like right after kalra lower like all the dancing

provide on right

artillery by turning around the world i think java

public static void main string args like

what is going on right we hadn't done a raise

then done classes with

fingering about static we certainly and methods then demand bremer past

so we just wait until the end of ninety cm now you know what's going on

now that we have a bad idea

now we can think about okay if this is kind of like the standard javaworld days

let me think about taking this idea and using its help me take my existing

programs that i've written and pack them up into a form so i can share them with

family and friends

so that's what we're going to do next

the basic concept of doing this as something that's called a jar file

and you've actually seen jar files before because you've been working with

something this whole time in your product projects

called pcm dot jar

this was just eight jar file

they contained all the atm_ libraries

so basically college are pile is where to get its name is not because it's like

i did a big mason jar although you can think of it like that

it stands for a job loc

archive

that's where the name comes

and the basically behind a jar file as this thing can contain a bunch of

different stuff most the time when it contains is a bunch of classes in job

and you could think of this is the compiled version of the classes

you can actually put source code inside of a jar if you want but most the time

when you get a jock

it doesn't have the source code associate with it it just has the actual

dot class five to the compiled version of the files

so you could put source pausing here if you want it

you complete data files in here if you want to put a bunch things in here if

you want

what we're really going to focus on the case of putting classes

so one of these already existed for you with a cm dot jar

and want to figure out how to actually create some of these ourselves

and use them because they could actually think of them as something that's

wonderful

were executed like ships and not confuse ramblings

so click on the computer

here's name sir

and then a natural working version of nameserver so i'm not going to show

press the files in case you're going to make this

but all the code in here and for the first thing i didn't mean surfer program

if i thought about me i want to think of this and the standard javaworld now even

though i'm do you still using the atm_ libraries

when i want to build this jar i want to build the joint away the sort of makes

maximally portable like i can give it to someone who's over here on the species

i've never here on the snack

and they don't need to have a klutz or anything like that they can just one of

the whole point

so the first thing to do

if the introduced my friend the main method

and so basically i put in the car that you just opt out at a method public

static void main as this array of strings called arc that sits parameters

that's just the way maine is always defined to be

and what it's going to do is create a new name sir project

and kick it off

and that's the only thing i need to add to my program so anywhere you had some

class

extended program

you would add these three lines of code

so basically get us sort of compliant with standard job

once we do that now we need to create this thing called the jar file which is

thing the racks would be able to x

one thing you might be saying to yourself this maryland you told me the

aclu libras already sort of provide this for me so why my putting it

explicitly in there is a matter of fact it's not super required to be in their

explicitly

the real reason why we put in their explicitly is to try to maximize

portability because even though java spoke at this property were like

uh... we would like the java code want to make a run on pcs in run on maxim

ic ron you know this time tiger and not for adults other stuff

in reality personal differences between these operating systems

and so little problems creep up here in there every once in while you actually

saw fuck you does in class on occasion

so your experience them in the letter

by putting in this one explicitly robin kind of relying on the code it in the a

c l_ libros exactly doing a bunch more complicated stuff right because

itni in for what the name of your class wise right you never told that

explicitly gracie i'm library

yeah i need a new one of these guys actually there's job as a story called

reflection reckon actually go in safe

i'll let me take a moment to reflect i'm going to go and look at the names of

your classes

and then do something actually generate some code based on the names of your

classes which is what it was doing

that kind of stuff going down a little bit coffee so we're just gonna say aid a

cm don't worry about it i'm just given it to you i'm a i'm a nice guy

say he's put this in to make it exposes our maximizes portability main reason

so how do we create a thing called a dropout what we're doing here

steps are all in excruciating detail on your hand out they don't need to worry

about scribbling down notes quickly but what we're gonna do is you first click

as the death multiple by the whole thing

you select the project that you wanna create the jobs are from so nameserver

and then we've got a farm and you and we pick export

to this whole time you were to imports when you are bringing stuff in and now

it's finally time for you to give something back to the world in the form

of export

so what you want to be when you click export is

it brings up a little dialogue box sometimes the sand clothes sometimes

it's open if it's not a big givers closed

an inside job when you click on jar products which you want to bring about

sniper and jar like on there for a permanent star if i can act

cams can take you through all the steps

we need to specify couple things your first we need to specify with in the jar

file salmon open up names are for and what i want to put inside the job cause

i don't want to have all of name surfer and the jar file it turns out

if you throw everything in there including the stuff called dot project

not classpath

it actually gets a little bit confused to some of those things are not germane

to what we want to pack up and our jar there just kind of other

uh... administrative information what we really want to have his everything

inside the default pack

so i just click on before package i can double click on this to make sure that

all of my java files are

that's what i want to my job i want basically all of my job file for the

compiled version of all blanco ob

job files

and make sure that this is click but by the father just make sure export

generated class files and resources

so what it's going to do is compiled those java files into that corresponding

class files

and that's what it's going to put in a jar

there are other options like i got export the java source file taiwan it

right then i get some of the actual source code

most the time you don't want to do this if you don't want people like sort of

sniffing for your source code just like there take the compiled by these are my

brethren give you the first timers like thirty days and my birth a good point

but we've got a given you this works

so once we have this

waiter now specified where do we want to save this jar file so that's what this

you know select the export destination what they should have a status

what you want to say that

that the export destination so where we want to say that we can browse around

where we want to save it is based on hard created a folder that has all my

name surfer code in it over here

i'm just gonna save the jar found that same folder so this is just in the same

folder for my project called names or for that has all of my class files in it

you don't put out wherever you want just don't forget where you quit that's kind

of the key

so this is why i'm going to say that so that's kind of sad

up and you don't need to worry about the options down here the options down here

just you know

they're fine faults that there are

then you come here to this point it seems like

olney what's going on export file compile errors of compile warnings yet

which one export everything we don't care

stories click

and then we come here this is the most interesting part of the whole thing

what we want to do when we actually create this jar file and this is

something we only need to do when we have other jar file but the a c ally

brief need to worry about

wait for what's known as generate a manifest file

basically all the manifest file is it's a complicated name manifest in backup

investors out forms like all what has been you know it sounds like you're on a

boat doesn't like to have the cruise director and i like all words the

passenger manifest

wrote a column manifested austin emphathize like two month long and then

you add one lines when it becomes three lines one

it's basically just a little bit of administrative information that's capt

around with your jar file

so knows all what kinda stuff for you using with this jar file that's really

all it is

so what we want to do is generate the manifest file we make sure save the

manifest in the workspaces check which it should be if you click generate and

test file

and then you need to specify where you want to save the manifest file

and the place i want to say that is basically in the same folder for my name

sir for project in the name manifests are usually the name you give it a good

browse around if you want to

but usually the name you give it is the name of the folder that all your project

stuff sent and then the name manifest destiny than actual name

answer any questions about that

manifest off

the other thing you need to do when you're specifying a georgia george just

a bunch of classes

it needs to know in some sense

if someone can that running this chart with you actually you'll see that in

fact you can run a jar

where should it start which class is the one

of which i should call its main

and that's what you specify here select the class of the application entry

points

is kind of a very formal way of saying

where should i start running

so the place i want to start running is it lists you all of the classes

that have a main method for those are all the ones and start running some

names are for the only one i click up and so it says the main classes name sir

and now there's no more next buttons now i can do is put finish

and i just created a juror

and you like are you guys got doubleclick doubleclick

or not there yet

now there's two things that you'll notice if you look over here in the

package explorer

you'll notice now we have something called a manifest fark is that's why i

saved it

and i also have names surfer jot dot jar the jar file i just created they were

both put in the same folder with my other

you know files that's why i want to save them so they have michelle from the

package explore now you're the funky things

even though we created this manifest in created this jar they don't have quite

the right information that we want to what we do is we double click on the

manifest file to open it up

here's the whole manifest file

it's got a version which is one point no

and it's not the main class which is named surf why does it know the main

classes nameserver

cuz i told it right that the application entry point just forward

letting me know that i told it

that's why the application starts

now there's one other thing i need

besides ducking for cover one can you get started

what i need to do it i need to say hey you know what

names are free and i think it's time

but you also need to use the aclu libraries and it says

how yet you didn't tell me about the same i've written you say well now i'm

going to add

the coveted third mondale and talked about in the manifest fosamax modify the

manifest file

at something called the classpath

and all of class that is it's actually looks just like this capital c dash

capital p

classpath just tells basically

uh... the application

what other stuff for using are there other jar files that you're using and so

what you specify here

is the name of any jar files that you're going to be using as part of your

program separated by space

some unease pcm dodge are here is a cm najjar overhear has

i'm way you'd be a cm libraries no drawn some jar file

and i'm also going to use the jar file i just created name surfer dot jar

if i had three or four more jar file that list them on the same line so if

you were going to write an application someday where you're like

hey i got this drop off my friend here the job by downloaded from the web which

i wouldn't encourage you to do

and hear the sardar falcon somewhere else his list of all your space in

between

and then you save the file that's the problem most difficult thing that people

forget it saved the fosse save the manifesto

and now what exactly do all this

created jawahar all over again placard

wife it's just like misaddressed

here and i was going to work

he recommended a little bit different if i'm robin dong a file maneuvering export

i'm going to take the advanced ports i'm going to write

like on the project name pick export

just says that brings up exactly same window

i'm going to export a jar file

i come over here why do i want to export sorry abt all this crap eunice again

what i want to export is not all the stuff i just want to export everything

in my default

why do i want to say that i want to save it in the same place i had before you

might say but now im

aren't going to replace the one that already exists

i need to replace the one that already exist updated my manifest i need say hey

buddy it's not just about you anymore

now it also involves a cm judge our like okay okay you can replace the old

so i'm going to put it in the uk

places before

now a quick next here's the thing about export warning export baritone karen

export

here is the only place where things are different

the second time i go through this whole thing i don't want to generate another

manifest file

cuz i generated a manifest file the first time and then i modified

what i want to do is use that modified to manifest file so i say use existing

manifest from workspace

which is again just a formal way of saying

yeah use the manifest part are you there

asked me where they manifest on strangely enough if you look

this is exactly the same tax this year

yang belgrade's it it's like

while real broader trapping the suns out everyone singin in the streets

that's you know you just say that that's the one you want to use its going to be

the same name

and now i noticed this

which class of the entry point is great out

it's great acts like a little bit before your entry point is named surfer

that's in the manifest file if that's already in a manifest on using it

doesn't need to know what again so it doesn't even like me specified again

so you know that's different

and then i click finish

and give me one last warning you sure you want to over i got last drop on he

was your friend he was hanging out with you since the beginning about

three minutes ago and i say yes long way

we we know each other that long thanks for playing

now i've created this drop on your life

primary

what you do now

i come over here and i said

or the jar file displayed

one thing i can do it the drop by the n_ double click on it

and by double click on the jar file

it just starts kicking off the names are propagation

right i don't need a clips anymore to go and ron and have little run big compile

i have a lap haitian unlike our yeah bob how popular it right now bob kind of

alfono means on that some other interesting ones are going to be the

other night off

six after the sixties

dawn done deal thanks for playing

so can you name your children vermont make a comeback

and so he interpret just kinda running here and it's fun it's just a little

stand-alone application

now if you want to pack it to the sop and send it to a friend of yours what

you would actually do he wouldn't just sending surfer about dot jar

what you would do is you would say hey you know what i want to do

i want to create

i'll i'll just do it in here

some new folder

so i'm going to create some new folder and all call this my programmer whatever

you want to call him talking to call it mean surfer again ferreting out for the

call mister my program

and want to put my program

that folder

if the jar

of my program

also going to put in the jar obviously enlai break as i also need that kind of

separate

and i also need in here and he gave the files like names dot data and not names

dash data reading about all the data to get reading on the program starts it's

not like magically that's just going to be very down right it's not going to go

in try to find out file

so i need to put all this stuff here

and now this folder or something i could zip up and sent to a friend of mine on

my friend get so they would be like all

nature provides our

and then they go

so now you can package up any program that you've written in this class

remember to put in maine

you got to go through started this to part

create the jar exporter process modify the manifest great other jar put it out

there again

but you're going to go

face any questions about that

now you can package up in and share with friends

now what's even cooler than sharing with friends that you could email stuff too

is share with friends on the web

as you just have mike you know millions of fans on the web most of the leaders

don't know about but they're probably you know in the late hours of the night

looking at your web page that exist

and you can actually take

anne

files that you crave your like jar files and make them available in a web browser

now there's one other thing i should mention the scandal thing before you

send now you go

credo messed up and send it off your mom or dad died monday i break our book why

it's a good time

in order for them to run your job clouds they need to have the java runtime

environment install

i remember on like the second week of class when we said although it is just

one oh six website

you need to download eclipse there's a thing called the jr you also need to

download

if you have a map

the jerry in most cases already installed if you have windows it's not

installed

they need to go and down you can actually sent into the cfo_ six pages

a day download the gary here is a copy of my cannot five

go ahead and install it

and then they can run your programs because your program can't run if you're

poor if the computer doesn't have a job or write it's a bunch of stuff is going

to execute java bytecode

if you'd like

what java bytecode allen told me were java bytecode is

i don't know what to do with it and so i won't run into any of the java runtime

environment

now assuming of johnson's summer have the java runtime environment

they could go to take a web page

and you might put some page on the web

yeah allows you to load your applicant your ap lit is just in web applied

version of your program

and so here

all look it's running inside a web browser right this is of the actual

application this is my web browser or cuz i could like from here go to

you know

i don't know some search engine

right i'm sittin in the web browser

i'm not just running a regular application

on my desktop but this guy's actually running in my web browser

how did i make that happen

here's how i make it

i create a web page

if you don't know about age ten on creating web pages

unfortunately i can explain that to you and five minutes

but what i can show you is basically what this bosnia look like so if you

know a little bit of html or you just want to essentially copy and paste this

idea

this'll work for you

so all you do as you say i want to decipher the entire page that generates

that allows your applicant run

usse this page's html state is all things called pat

the name of that page is named surfer an acquittal table on the cradle border

around my applications but i want to business

what's my application my whole updation is right here

i have a catholic

what's the name of the archive

which is a java archive the contains my applicants name surfer dot jar

code is what's the entry point right this time no longer have the manifest

file available to it so it does what's my entry point

named jeffrey dot class that's where you start running felt that i want to go to

nature for dot class fine with me now if i start running

and the space i'm going to give you are running on the screen is five hundred

seven hundred by five hundred

and that little snippet of code

is what goes on whatever web surfer this webserver this is sitting on

looks for those job clouds

slaps them into the page and then someone good to go to running for java

program inside of us

just wondered how many people know html

you folks are over summer some number folks that this might be reasonable

thing to do if not you just don't need to worry about it it's not a big deal

just send the application your friends

the one i can use you know if you create a little webpage

is that when something is running on the web page it does not have access to the

rest of the files

what that means is

if i actually happened to be over here notice i have index dot html i have name

surfer dodge are not have a cm dot rar

what happened to my name's dash datafile

yet it doesn't exist

why doesn't exist 'cause i couldn't really anyway 'cause once i'm running on

the web browser for security reasons it doesn't let you get going to pull stuff

out of your files

okay 'cause evaded people could you really bad things your computer

what you need to do if you're like a mountain where is that data you you

minus running show from the web what'd you do

yours fears the dirty little secret

actually created giant array that had all the data in it

and made a part of the program

so sometimes you can do stuff like that if you don't want to actually read from

a file

the other thing you can do is you can take those files and include them in the

jar file

to the jar copy not only have compiled class in the cars have data files about

another way of doing if you want to do it

but we just don't have time to talk about the decals those kind of the same

process

and when you're exporting stuff the dropped by use of something data files

so that's clearly executed

now i know that we know all this funky stuff about all acts to go back put on a

web page if i want to just like you know feel unhappy i'm going to go

it's time to come back to our friend

standard job as a standard java what kind of allowed us to all you know think

about doing to stop as we learned about me

and i want to show you a couple examples of program could actually don't use the

aclu libraries at all

to show you why we use the a c my brisket one thing you might be wondering

if

why weren't we just doing the standard java thing the whole time

and part of the reason is

things are just so much easier and cooler when you have the same way myself

we go back over to a close

we're coming down with names are for an office manifesto

here's a program that's written in standard java rights at hello world on

the screen

this is something you could down in the first class by saying public last hello

world extends console program imprint lane

hello world out to the screen and you would have gotten it in the consul

so what's different here what's different here is we have public last

hello world

and it doesn't extend anything it doesn't extend program doesn't extend

concord program

there's no imports for the a c l_ libraries we're not using any defense

so we don't have a console program we don't have a nice little consul

but we white stuff out to this displays a nice little window

while we do have a something called the system output consul and if we want to

put stuff on back it looks real seller to what you had before we'd use print

land which is why we made the method that you use call prints match theirs

but weeks a systemic dot out dot println text one print out

again here i have a meaner it might mean that they can have whatever i want and

that's just for execution starts

so if i compiled list

and running

let me just compile and run to show you why

hello world in kind of this world is not all that cool

careful our world

it just ran

and they're like partner and i don't see anything

cuz you don't get a call we know that comes up is like a lower over here i am

on this window for a budget act

you have what's called the system console

the system console like you happen to be using a development in violent like a

klutz or something else

is basically just a window in that development environment that shows

messages that you print out

if you happen to be in the bad old days but i think i raised over here where you

have command-line text we actually type stuff in

because i would just be that same window where the text would appear where you

can't

so if you don't get it in a separate we know it is not all that will get a lot

of times would notify closed anyway so you don't see a

now if we want to pick up a notch it's a token on yahoo so wide use the consul

one i do something graphical so here's graphical hello world

and so what we want to do is

we want to create a window

a new window that is going to have some title associated with it and we're going

to put the text hello world in that window

why we need to do what we get worse to excuse respectively

we need to create something called a j three in which you never have to worry

about before

what they gave frame it's actually a frame that's going to pull the window

so it's actually one week run we're going to start running rapidshare

it's going to create a little window force that we can display stuffing

well we're going to put in that window

we're going to put a label j labeled you've seen before this is just like

you've seen before

we're going to create a j label that's called hello world

and we want this label to be centered justified as opposed to left just

fighter rightist five tiny stage a label dot center to center justified

if i don't give a destination it'll by default be left justified looked kind of

because one attacker

and then i grabbed this label to my frame

so similar to the idea cabinet can listen adding stuff to the candice's

exactly analogous right we want to make it just as easily when you saw standard

java

all the same concept applied

here were just adding the j label which as you know now is a g component in the

big java hierarchy

and j components can be added to ge frames

so we have a jail able to get at a twenty three

i set aside tragic frame which is five hundred by three hundred that tells me

how big the windows going to be when it starts

and then there's the other crafty stuff but i need to do that just you would

think alike

why do i need to do that right it's just doesn't make any sense

that i would not otherwise want to have it this way what you're going to do

if someone clicks close on the window a little x the top of the screen to close

the window

i need to say hey

if son click that then you need to close yourself otherwise the window by the way

the application keeps running

which seems odd but we need to have that they're pretty optician stop running

and then we think

window yeah i know i created un everything

you need to make yourself visible

otherwise no one will be able to see you

why when i pray that we know that i was i going to make a visible

that's how we use the a c l_ libraries

so we need to make sure that this guy visibility is true

and appear on this

you're a graphical hello so after all the squawk to write

yours graphical lovro

we do have one and all of that explain to you so that you could get hello world

bring your like

somewhere in the social now work in a corner need to worry about how the world

in the middle of my screen

that's cuz you have this new hybrid

so like okay let's let's keep it up even one more not shit you know i couple

right what are those now stopping interaction like that should be

something that maybe you know i get some benefit from having to stand for java so

out of interactive version of hello

through the interactive version of lalo na some of the stop should begin to get

a little bit more

repetitive in the sense that you have your main you have your j frame the

frame is called interactive flow that's the title of that window

what we're going to add to this day play with a new

class that we're going to create called a moving label

and i'll show you what a moving label doesn't just second but we need to set

aside the window

again set default close operation exit on clothes

and set visibility to true so baseball this does is create this window or

particular size

and if you add this thing called a moving label to it and moving label just

another class i create what's a movie label

a moving label is a j component

it needs to be a gay component because i want to add a tool for

and to display something to frame i what i can only display components knapp

brings this can extend component

and it's going to implement our friend of mouse listener

because it's going to listen for the past year what all i remember mouths

listener that's why like the mouse got click and drag at all that stuff sans

act the same

so i have my construct ojai constructor had to have some starting texas label

and starting x and y location

thatcher what kind of familiar to you

anti based i guess tore off the tax expert yet to like

and this guy wants the lesson from out of that

so ted adam else listeners and it needs to say

if you get some out of that

send them to me to send them debits switches

so this a little bit different than what you've written in your programs before

where you just said you know adam alice was knowing you didn't you just had an

open print close pronounced 'cause we kind of poop

naturally by things get a little bit funky

the difference between this and thinking about having some sort of label that you

just display on the campus right some taxes just put up on your canvas and it

just sits there and it's fun

is that this guy i know i have to worry about what's known as painting itself

which means it needs to draw itself on the screen your like but when i have

labeled before they just knew how to draw themselves

yeah that's because we gave you a label does a little bit smarter knew that it

was a label that should rockville

this guy needs to be told you're going to draw yourself

though that they call paying component that gets called whenever this guy

should get displayed on the screen or some other thread that's going to call

the for you automatically

and it says here is the graphics

context in which a dryer self

safely within our graphics contact somebody draw some strength

and that's a method name everything is not important here i just showed you

those extra craft you need to worry about right which is why we didn't want

to do all the stuff began

now this booking steamy or whatever the mountains clicked i get the new acts

wire location

and i repeat

what is repaint meaning to redraw yourself

and i'm going to redraw myself at this new xy location because when i call

repaint

someone comes along and says hey to repaint this area

i'm going to call dual pane component method so you can read paint yourself

you like

well this is really we are now in like almost we're here i get a mouse click

and i know that i want to drop my sri drama itself but rather than telling

myself directly to redraw myself

i don't tell the system paid i'll need to get repainted in the systems as

possible

uh... as the sort of like

you know that java high allison arafat happiness are pointed you want to know

like you need tear

someday if you act like they were anti-war

we won't get in

units i can breed on partner

other hot

you know i think i need to repay my topic how to fix that those are ok you

need repairs are four one i'm ready for you to repeat yourself

all call your pain components method

until then no no you don't repeat itself

and saturday that's other stuff in the system to worry about all yall in there

with you you have to get repainted

okay now call your pain component you come a long thick

all cable nominee promised off the new act violently

so kinda convoluted the whole notion of like

you're doing something here and you're asking someone else to do something for

you and i'm going to call you back to do what you were julian sands

now makes a little bit more sounds after we talked about directed at you've seen

all the stuff

thurday class not so hot

so if we were on this

this is called up interactive hello

base but where does it just brings up the article that sixty s by six a rocks

in the middle of the straight and not everytime i click them

mouse button right because this is the mouth with the bank over here

everytime i click the mouse button

the x_ y_ location of the mouse becomes the new base point

for the tax they get stronger

and so i just moved to rounds

any questions about that

so there's a standard java

you've seen all the concepts in the a c we using the atm_ i've read the

concepts rather saying the notion of adding things and i should have about

seles has not affect the whole mouth listeners concept we just took the

standard job ideas and use them sort of in conjunction with used him libraries

but there's a lot of things in the a scam i break it just made it so much

easier to like for example b graphics contest entries or to write a social

network for whatever and say you're welcome to continue using the atm_

library dot

but some people are wondering wide will use these libraries and this is the

reason why there's just a whole lot of propped you'd have to worry about

i'm question

you'd be use in like you know your favorite word processor like notepad

and there's actually some places which i won't you know name but that there is

it's actually reasonable that you know that some schools and your first

programming class what you do is they say while you need to have like no

pattern you need to have some text editor

and then we're gonna do command-line stuff you're gonna type in like name

surfer names dash data dot textron your program and then everything's gonna be

taxed

so one thing i want to leave you with now in our final few moments together

sort of a notion we were starting to meet next week talk about life after the

five had to give you notion that if you want to go on in terms of learning more

about java specially standard java

we said i just started things off by giving you you know this book which

talks all about the cm libraries and this i think is a great book to actually

learn everything with a new vcm libraries

but if you want to go on worth of other resources you can use

that's not pretty if you don't like the java section of any bookstore just would

be practiced a while one but i would recommend not that i get my kickbacks

restart called learning job a it's actually pretty good time some of the

examples just off your actually based on this book it's a little bit

that's why we don't use the text book in this class if in fact and we get up did

we break two thousand page mark

all right so close it so close with the index

now in nineteen

that some other books that actually the original specification of the java

programming language the same older version of the book is this is one that

was like a week candidate if you are not the old version

i forget which version of acting out a second edition i think now there are

like three or four some impact

looks a little bit bigger birds actually

four books it specifies the language job it's actually very well written as a

reference inside of recommend this as well

if you're going to like all i want it all

the big job

is vague

i think it might actually crossed the thousand page all yachts like thousand

the spirits like twelve hundred

and if you really want to get a hard time like but now i'm all about web

based java

java server programming like everything or do i like a lot of things you don't

want to know if whatever they want to know one more

and that's just a small set

right so they're just a few bucks i'd recommend if you want to go on beyond

this class

but you can go into any bookstore news get inundated with a ton of stuff but

now you have a context for kind of putting all the pieces together because

you've seen all the other things that you actually need to know to be able to

work with the huge set of tools that job actually

so any questions about any of our staff

you're going to go

alright power to a couple minutes early cuz most the time i like to go a couple

minutes late

have a good weekend