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You have completed Java Loops!
You have completed Java Loops!
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Also known as the For Each Loop, it’s a simple way to process each item in a group without worrying about counters or indexes.
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Hey there.
0:01
Are you feeling a little loopy after that
last one?
0:02
Don't worry.
0:04
We're going to cover a loop
that's pretty handy when you want to go
0:05
through an entire set of things,
one by one,
0:08
without worrying about the details
of a conditional and a stopping point.
0:11
You provide a list of things,
and it goes through them all.
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The loop is called the enhanced for loop,
or the for each loop.
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The syntax is clean and simple,
but there's one small issue.
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This loop will only work with something
that is iterable,
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meaning it could be iterated over.
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So it requires a group of values
of some kind, and since arrays
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are likely in your near future,
I'll provide some of those for us to use.
0:37
Sounds a fortune cookie.
0:41
"I sense a raise in your near future."
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Anyways, let's open up our workspace.
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Okay, let's open up foreach.java.
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If you're wondering why these class files
are here now and weren't before,
0:53
I got pulled away for a moment by my kid
and had to refresh the workspace.
0:56
You should have them too,
1:00
but they don't show up automatically
after compiling your Java files.
1:01
You can right click in the sidebar here
and choose refresh and they'll pop up.
1:06
Not important though.
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You can see here
I've provided you with two arrays,
1:12
an array of strings
and an array of integers.
1:14
If you're already familiar with arrays,
fantastic, you know what's going on.
1:17
If not, this is basically a super handy
way of storing
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multiple values
of the same data type into one variable.
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I know it looks a little weird, but please
don't worry about this just yet.
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You'll learn about arrays soon enough.
1:33
For now, just focus on
how the loop picks out each item,
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one at a time,
and runs the code inside the loop with it.
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Let's play with this string one first.
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What I have
here is a list of the final name options
1:44
my wife and I had to decide from to name
our kid.
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Most of these were my ideas.
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Let's loop through them
with an enhanced for loop.
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Here's the syntax.
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We type for, some parentheses,
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and our curly braces, exactly last time.
I know you're probably having nightmare
2:00
flashbacks but don't worry. The difference is
what happens in these parentheses here.
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I'm going to comment out this integer
array down here for now.
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I don't want these distractions
becoming distractions.
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We provide a local variable here,
which will contain
2:18
the currently
iterated over item in our list.
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So we give the type, a variable name,
and then we put a colon.
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On the other side of
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the colon, we provide the iterable
we want to loop over.
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Then, as always, in the body we provide
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what we want to happen to each item.
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So let's change this type here to string,
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because these values are of type string.
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And let's just use
name as our variable name.
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We can name this anything we want,
but let's keep it relevant and readable.
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This is a list of names, right?
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Over here we add what we want to loop over,
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so let's add the baby names array. Cool!
3:00
As usual let's just print a line.
3:04
System dot out dot printf
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let's do percent s
and a percent n for a new line
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then we'll use our name variable.
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Let's run this and then we'll go over it.
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So we got
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clear and javac for each dot java
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and java for each.
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Cool,
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we got all of our names printed out
nice and clean.
3:32
So on the first run of the loop,
our variable name held the value
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of the first value in this array,
which in this case was Bruce Wayne.
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After the code block ran, it went
and grabbed the next item in the array
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and plugged it into our name
variable, Donatello.
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Great name. And so on.
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So anytime we use a for each loop,
it will run through everything
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you give it without stopping
until there's nothing left.
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But we can also use those break
and continue keywords.
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In fact, you can use those keywords
in all of the loops we gone over
4:05
in this course.
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Let's reenact history
and break out of the loop
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the moment we get to the
name my wife liked the best.
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So let's add a conditional.
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If name equals Enzo
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System.out.printf
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It's %s and that's final,
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plugging in our name variable.
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And break after that.
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Let's place this in an else
and add a question
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mark to the end of this one down here too.
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Let's run it.
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I'll use the up arrow
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to get back to the last command.
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Awesome!
4:59
As soon as we hit
Enzo, it broke out of the loop.
5:00
And we were just
getting into the good ones too.
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Oh well, at least nicknames are a thing.
5:05
So far, we've been primarily
just printing lines to the console,
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just to keep things clear
as they're happening, and to not bring on
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any extra potential confusion
with complex code,
5:16
as we're trying to learn the syntax
and functionality of these loops here.
5:19
But, I'll give one more simple example,
showing that you can really do
5:23
anything in these loops.
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Let's play with this integer one.
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Since the kiddo had distracted me
just now,
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I decided to log how many times a day
my kid pulls me away from my work.
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So this would be Monday, five times.
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Ugh. Alright.
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Tuesday was only once. Not bad.
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He was out of the house that day.
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326! Alright,
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that one's an exaggeration,
but that's how it feels sometimes.
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You parents know what I'm talking about.
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What I'd like to do
is add all these up into one big total so
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I can use it against him when he's older
and he's saying that I'm bothering him.
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Now we could grab a calculator
or our phones,
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but I don't want to be sitting here
for 20-30 seconds pushing buttons.
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Let's make Java
do it for us with a for each loop.
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Let's get the structure set up.
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For and we use int this time as our type
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Let just say num short for number, colon.
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And we want to iterate
over this distractions array this time.
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Real quick, let's create a variable up
top here to keep our growing total.
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We'll say int total equals zero.
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Cool.
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Now let's work all this into the loop.
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Within the body,
we'll say total plus equals num.
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If you're unfamiliar,
that's the same as saying
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total equals total plus num.
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After that, let's system dot out
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dot print f percent d
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and a new line, dropping total in there.
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So we should see the new total each
step of the way.
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Let's try it.
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I'll hit the up arrow.
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Cool.
7:10
We started with 0,
and you can see it added 5, 1,
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then 326, and so on.
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Once it ran out of numbers to loop over,
it automatically terminated the loop
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with no problems. Fantastic.
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Wow, that's a big number.
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I'd better go teach Lord
StinkyPants how to chill out!
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So the enhanced for loop is a neat way
to say, for each item in this group,
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do something, without having to manage
a counter or worry about when to stop it.
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It's clean, simple,
and less likely to cause mistakes.
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This is your best friend
if you have a group of something
7:45
and you need to loop over every item
in it.
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Don't forget about the break keyword
if it's unnecessary to keep going
7:50
passed a certain point.
7:53
I hope this has
7:56
sparked ideas for you
on all the amazing things you can do with
7:57
loops in your programs and all of the time
that's going to save you.
8:00
They're an absolute game changer.
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And as I said, when you start to learn
about arrays, lists, and things that,
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you're going to be using both of these
for loops a lot more,
8:11
and you're going to get super comfortable
with them, and fast.
8:14
So don't worry if they seem
a little overwhelming right now.
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I hope you all enjoyed this,
and for each student,
8:21
in viewers,
system.out.print, thanks for watching!
8:23
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