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In this video, we're going to cover the solution for part one.

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Each class that models an object was placed inside the model's folder, and the main class is by itself.

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We'll start with task one, and that was to add all the necessary fields to the contact class, and

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if you were to look back at the article, the fields were private string name.

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Private string, phone number.

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Private string birthdate.

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In private and age.

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And task to reminds us that if a class has failed, it needs to apply the big three steps, the first

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step is to create a constructor.

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It's only going to receive three parameters.

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String name.

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String phone number.

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And string birthdate.

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And you might be thinking, why not?

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For while the birth date needs to automatically determine the person's age, it doesn't make sense to

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ask the user how old they are if they have already given you their date of birth.

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All right.

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The constructor runs when you create a new object.

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So we're going to set every field in that object equal to a parameter.

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The star name, the stop phone number.

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Equals phone number.

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And they start birthdates.

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OK, so how do we get the age from the birth date?

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Back in the article, I left you a lot of hints on how to achieve this.

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And the first step was to create an object of the simple date format class.

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So we'll say formatter.

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Is equal to a new object of the simple date format class.

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And inside, we need to pass the format that we expect our dates to be in.

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They're going to have the format of month, month, day, day.

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Yea yea.

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Yea, yea.

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And make sure the EMS are upper case, because that's how the formatter interprets months, your next

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instruction was the research to pass the string value intimidates, and I hope you're able to figure

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it out.

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We can call the pass method from the formatter object.

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And what that's going to do is receive a tax value and from that string, it's going to return a date

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object.

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So I'm going to pass it the birth date string, and it's going to convert that string to an actual date

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object and return it.

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So we need to store the return value inside of a variable of type dates.

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I'll call it two dates.

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Because we're converting from a string to a date.

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OK, now the pass method throws a checked exception, we know it's a checked exception because Javas

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forcing us to catch it.

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Do not try catch the failure inside the constructor, whoever is calling the constructor, it's their

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job to handle the failure.

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So we're going to throw the exception from the constructor throws pass exception.

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So that whoever is calling the constructor, they're going to handle the failure, the constructor's

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only job should be to update Fields', nothing else.

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So going back in the article, the next step is to convert each date into the number of milliseconds

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since 1970.

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We can go to the documentation for the date class and look for a method that does this, as I scroll

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down, you'll see that many methods are deprecated.

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That's pretty crazy.

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But interesting enough, this one isn't it returns the number of milliseconds since January 1970 up

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until the specified date, and it returns it as a log.

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That's perfect.

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So I'll have to say long to Milli.

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Is equal to to date and from we're going to get the time.

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So this line converts the string to an actual date.

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And this line converts the date to the number of milliseconds since 1970.

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The last thing I want to do is get the current date and convert it to the number of milliseconds since

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January 1970, then I can get the difference between the two in milliseconds, which is basically going

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to be the person's age in milliseconds, and then we can easily convert from milliseconds to years.

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So we'll say long def.

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We can get today's date by just saying new dates, we're going to convert the current date to the number

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of milliseconds since 1970 and from today's date, we can subtract the birth date.

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So this is the number of milliseconds from 1970 until the person's birth, and this is the number of

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milliseconds from 1970 until today.

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So death is the person's age, but in milliseconds.

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But before we can continue, I did all of this in separate steps to walk you through it.

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I want to make the code shorter.

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So I'm going to add this right here.

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And now with just two lines, we're getting the person's age in milliseconds and the next instruction

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was free to research how to use the time unit class to convert from milliseconds.

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Today's.

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Your research would have a junior right time unit.

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Milliseconds, two days, and what that's going to do is take a value in milliseconds, in this case

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death, and convert it to days.

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So now we're going to get the person's age in days.

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And then if we divide the number of days by three hundred and sixty five, we'll get their age in years.

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But the age is an integer and the two days method returns along.

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So the final step is to typecast this long to.

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All right, we can finally test our code at the very top, you'll notice the line package models basically

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tells us Java, hey, the contact class is inside of a separate folder.

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So now inside main Java.

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We can import the class from the models folder.

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And we can also auto complete imports and TVs code just half way I.

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And now inside the main method, we can create a new object of the contact class.

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His name will be Alan Turing.

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With the following phone number, just some random number.

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And their birthdates.

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OK, I'm also going to print the object, even though we don't have a to string, I'll just leave it

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here for later.

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And here we get an error that's because of the contact constructor can throw a pass exception pass exception

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is a checked exception.

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And if you want to call this constructor, Jebba forces you to try to run the code.

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And if the code happens to fail, you need to catch the pass exception.

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And we'll just print the message that comes out of it.

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Then we're going to add a finally block, that prince.

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Process completes finally is always the last thing that runs regardless of the results.

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All right, now I'm going to go to break point and step into the constructor.

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Here we can see the parameters that were passed in.

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And this points to the current object that we just created, the stock names, that's the name field

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of the current object, equal to the parameter, the phone number updates, the phone number field,

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they stop birth date updates, the birth date field.

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And we're just going to step over the formatter object.

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I'm going to step over these function calls.

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This is Alan Turing's age in milliseconds.

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And in this last line, it's going to convert the age to year and update the field.

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And just like that, we created an object of the contact class.

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And if you keep stepping over the contact variable stores, a reference to the object we just created.

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And finally, it's the last thing that runs, regardless of the result in this case, we know that the

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process is complete.

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Now, what happens if I change them month, something that doesn't make any sense?

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I would expect the parties function to not be able to pass the state and throw an exception.

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I'm going to relaunch the debugger.

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But instead, it falsely interprets the input, it doesn't make sense for the H to be negative.

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That's not good.

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The past method should have thrown an exception, it should not have been able to pass the state and

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the task was free to research how to stop the formatter from being lenient when it's passing the string,

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the string that we pass and needs to strictly adhere to the format.

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Month, month, day, day.

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Yea yea yea yea that we specified.

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I told you to look inside the documentation for a method that specifies whether the date passing should

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be lenient, and I hope you are able to find the method lenient, which expects a boolean.

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And if we go back to our code, we're going to set the leniency to false.

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And now I expect that it's going to strictly adhere to the format we Pastan and it's not going to tolerate

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anything else.

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Relaunching the debugger.

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I'm going to keep stepping into the constructor until we reach the pass function.

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Which is going to fail and throw a pass exception.

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Here we catch the checked exception and print its message.

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In this case, it says that the date was unpassable, as always, finally is the last thing that runs

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and whether the process succeeds or fails, we know that it's complete.

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That's all for part one.