- Reviewing Our Feedback 6:11
- Conditional ints 3 objectives
- Parsing Integers 3:46
- Parsing Integers 1 objective
- Censoring Words - Using String Equality 4:51
- String Equality 2 objectives
- Censoring Words - Using Logical ORs 4:31
- Using Logical ORs and ANDs 5 questions
- Censoring Words - Looping Until the Value Passes 7:16
- Looping until the value passes 3 objectives
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Parsing Integers
3:46In this video, we look to the Internet for assistance in figuring out how to retrieve an integer from a String.
So we left our program in
a bit of a broken state.
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What we wanna do is prompt our
user to ask how old they are.
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We know how to do that,
as we've done that already, right?
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But there's a slight problem.
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The method that we've been using,
readLine, well, that returns a String.
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But as we know now,
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when dealing with numbers we want
to use the Integer data type.
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So somehow we need to get
an int from a String.
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I know, how about we ask the Internet and
see what we get back?
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Okay, so I'm gonna go ahead and do a
search for exactly what we're looking for,
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which is Java get an int from a string.
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And we'll take a look at what we got here.
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This very first one is from
a website called Stack Overflow,
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which is a great resource for a developer.
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Lets see if it's, indeed,
what we're looking for.
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It says here, how does one convert
a String to an Int in Java?
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That is exactly what we need.
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See, I have a string which
contains only numbers, and
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I wanna return a number which represents
it, which is what we want to do,
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cuz we want to use the Int
to be compared in there.
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So let's go scroll down to
what the answers are so
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that you see there are seventeen answers,
and this one has a thousand votes.
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You can upvote if it worked for you, and
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then there is a check mark saying
that this worked for that person.
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So let's see if it works for us.
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So it looks like you use
this Integer.parseInt.
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Look there's a link to the Java Doc.
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Let's go ahead and click that,
this is the actual Java documentation.
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So let's see.
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So it says that parseInt will return
an int, and it takes a String,
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which is what we have.
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This looks like exactly what we want.
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Let's go ahead and
let's jump back over to our code.
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And let's pull out the age from the line.
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So we're gonna pull out a String first.
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So we'll say console.readLine and
we know that that gives us a String.
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We'll say how old are you?
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Great.
So now we have ageAsString is a String
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variable, so let's go ahead and let's
change this int age that we have here,
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and we'll say Integer with
the capital I .parseInt,
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and we'll paste on that ageAsString.
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Great, and now I'm gonna save it.
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And let's see if that worked.
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File and run.
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And it says how old are you?
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So let's try and
make sure that it fails and say 10.
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Great, that worked.
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Let's go again one more time And remember
we said, so if they're older than 13.
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So let's go and say they we're 15.
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Excellent, it started working.
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So, if you're in a program
that's executing like this,
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you can always press Control-C and
it will stop.
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Great job leaning on the Internet.
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We now know how to parse
Integers out of Strings.
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This is also referred to as
converting a String to an Integer.
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Switching between types is
also often called casting,
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which we'll cover in a future course.
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You also did a great job ignoring the fact
that we introduced a new class Integer
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with a capital I.
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In the past, we were using the all
lowercase primitive data type int.
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We used the new Integer
class's static method parseInt
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to generate a primitive int.
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This capital I Integer here is what is
known as a wrapper type, or a boxed type.
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And what it does for
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us is it provides some methods that we can
use to manipulate and produce Integers.
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Remember, primitive data
types do not expose methods.
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So there are these wrapper classes for
every one of the primitive data types.
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Again, the other data type that we had
worked with in the past was String.
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We're going to need to explore the methods
available to us because I'd also like to
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do something about those names I was
being called during our beta test.
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But first,
let's do an exercise on parsing Integers.
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