Sentraxis in the Internet of Things Infrastructure Industry

Sentrax

We are now on part 6 of learning how to code and in this installment we are going to focus on learning about functions. For this lesson we are going modify our program created in . However before we get started make sure you create a new package named and create a new Kotlin file named . Awesome, let’s get started. part 004 part_005 app I first want to talk about what a function is and what it might be called in other languages, basically I want to give some background on this topic before diving into the actual lesson. Functions help to promote code reuse, instead of having to write the same logic over and over again you simply package it into a function and it can be referenced in other areas of your application. In other languages these may be referred to as methods, but in Kotlin they are called functions. If you are feeling a little nervous, don’t, we have been using functions since the beginning, it’s the thing that is called main that our applications have been wrapped in. For our lesson I want to take the work we did from our while loop and wrap that into a function so instead of printing only until we find a car with in the name. It’d be really nice if we could pass in a String and it will continue to loop until it finds that. So that’s what we are going to do. ford Let’s Get Started I’m going to provide a template that you can copy and paste into IntelliJ, actually please do because I want to also show you how autocomplete works. fun main(args : Array<String>) {

    val cars = arrayOf(
            "Toyota Camry",
            "Toyota Corolla",
            "Honda Civic",
            "Nissan Altima",
            "Honda Accord",
            "Hyundai Elantra",
            "Nissan Sentra",
            "Ford Fusion",
            "Chevrolet Cruze",
            "Hyundai Sonata",
            "Ford Focus",
            "Mazda MX-5 Miata",
            "Fiat 124 Spider",
            "Subaru BRZ",
            "Toyota 86",
            "Nissan Z",
            "Dodge Challenger",
            "Ford Mustang",
            "Chevrolet Camaro",
            "Audi TT / TTS"
    )

    printUntilFound(cars, "ford")
} Right now you should notice that printUntilFound is in red. Depending on if you are using Linux, Windows, or OS X the keyboard shortcuts for this action will differ so instead of giving you a set of keys to press I’ll just show you what you can click. As homework please do look up the at some point in time. keyboard shortcuts for IntelliJ If the red lightbulb doesn’t appear, place your cursor over the name. You may have to click on different letters or over over different areas, but be patient and it will show up. Once you select Create function 'printUntilFound' you’ll notice that it generates a method. Press enter on the keyboard until it generates code within the function (known as the function body). You should see something like this. fun printUntilFound(cars: Array<String>, searchTerm: String) {
    throw UnsupportedOperationException("not implemented")
} So what exactly are we looking at? The first line is the definition of our function. It contains the name, printUntilFound along with the parameters to pass in. The first parameter to pass in will be an Array of String objects, it’s named cars. The second parameter (which may default to s when auto generated) is named searchTerm which is a String. We will use searchTerm to essentially replace our hardcoded reference to ford. The function body will currently throw an exception, which means the application will crash if we don’t handle that exception. This is one way to ensure that our code doesn’t call an empty function that doesn’t do anything. It can be useful in larger projects where you may think you are calling a function that does something but it was actually never implemented. Typically you’ll be deleting this right away and adding the logic required for the function. One part about this function that may be confusing is we now have cars referenced in two spots of our application. So if it’s easier to understand, feel free to rename cars to something like carsArray. Let’s Fill In The Body So now it’s time to actually fill in the function body. Since you’ve already completed this for I would suggest trying to fill it in on your own and only look at the completed body if you get stuck. part 004 Awesome, let’s go ahead and compare notes, here is what I came up with. /**
 * Prints out a list of cars until it reaches a given search term.
 * It will print out the car that matches that search term and then
 * it will terminate.
 * @param cars a list of cars to print out
 * @param searchTerm the search term used to determine when to stop
 *        printing out cars.
 */
fun printUntilFound(cars: Array<String>, searchTerm: String) {
    var wasFound = false
    var index = 0;
    while (!wasFound) {
        val car = cars[index]
        println(car)
        wasFound = car.toLowerCase().contains(searchTerm)
        index++
    }
} Okay so you probably didn’t include the function documentation, and that’s understandable because I never mentioned it. Documenting your code is very important, especially when you are working with other engineers. In two weeks or a month you can come back to this and know exactly what it should do. Another nice part about documentation is it reinforces that your function makes sense. There have been several times where I changed a function because I couldn’t easily describe it through documentation. I could go on for an entire article about documentation so I’ll digress for now. So within this function body you should have replaced "ford" with searchTerm and that’s really all that should have changed. Now within the main function when you call this and pass in ford you should notice that it does exactly what it did previously. Go ahead and add printUntilFound(cars, ) to main and notice what happens. when you run the code. It should now only print out four items ending with Nissan Altima. “nissan” And that’s an overview of . There’s more to functions and we’ll likely go over them more in the future. One thing I did not talk about in this article are return values in functions. A return value is what you return to the call site (where the function was called) after the function has completed. functions in Kotlin And that’s it for this article. As always if you have any questions or comments feel free to leave a response below. As an aside, you may have noticed there was no article about Kotlin last week. I strongly recommend that you follow me over on Twitter as I will always send out some announcement if I have to delay an article. Cody Engel (@POTUS404) | Twitter

Let’s Learn How To Code Using Kotlin — Part 005 — Functions

Wow, can you believe we are already on our fifth installment of this series? If you are new to this series I strongly recommend as each part builds off of the previous parts. In part four we are going to continue learning about control flows by learning about the other loops in Kotlin. However before we get started make sure you create a new package named and create a new Kotlin file named . Awesome, let’s get started. going back to the introduction part_004 app In this example we are going to print out a list of cars using three different approaches. In order to get a list of cars searched for “best sports cars 2017” and . Feel free to either steal my list or come up with your own. Our first step in creating this program is by creating an array of String objects. For my program it looks like this: found this article over on Car and Driver val cars = arrayOf(
        "Toyota Camry",
        "Toyota Corolla",
        "Honda Civic",
        "Nissan Altima",
        "Honda Accord",
        "Hyundai Elantra",
        "Nissan Sentra",
        "Ford Fusion",
        "Chevrolet Cruze",
        "Hyundai Sonata",
        "Ford Focus",
        "Mazda MX-5 Miata",
        "Fiat 124 Spider",
        "Subaru BRZ",
        "Toyota 86",
        "Nissan Z",
        "Dodge Challenger",
        "Ford Mustang",
        "Chevrolet Camaro",
        "Audi TT / TTS"
) You might be wondering right now what arrayOf is or even what an array is. To answer the first question, arrayOf lets you create an array of objects, in this case they are strings. To answer the second question an array is a collection of objects. That collection will typically have some commonality, in this case we want to represent a list of car names. It’s also probably important to note that each item is separated by a comma , with the new line being optional (but it can help with readability of longer arrays). As we get further into this series we’ll discuss other types of collections along with the pros and cons of them. In general an array is the most basic type of a collection and serves as a building blocks of several others. While this may fall into “Too Much Information Cody!” I also want to point out that arrays of things are generally how apps work. Your Facebook wall is powered by an array of Posts, Medium is powered by an array of Articles, and YouTube is powered by an array of Videos. These aren’t the exact implementations, and are instead simplified examples. With that out of the way, let’s start printing out these cars. The Basic For Loop So now it’s time to iterate over this list of cars and do something with them. In our first example we’re simply going to print out the cars, one car per line. Here’s our first example: println("\nPrinting Cars In Order")
for (index in cars.indices) {
    println(cars[index])
} So this is technically not the most basic for loop, instead I wanted to give an example of you might do this in Java (or other languages). Essentially what we are doing is getting an array of indexes (which are integers) with cars.indices, and we are iterating over that list. What this allows us to do is access the array by its index. If I wanted to only access Toyota Camry I would simply reference cars[0] which is the index of that car. With arrays they always start at zero, and so if I wanted to access Toyota Corolla which is the 2nd item in the list I’d reference cars[1]. Our loop above will start out at zero and end at nineteen (our list has twenty items). Performing Operations On The Cars The next example I want to give is how we would perform operations on these cars. The easiest example I can think of is printing out the car names in lowercase letters. In doing so we are also going to access the cars directly, so no more index. In general this is how you probably should iterate over items in a list in Kotlin. Here’s what that looks like: println("\nPrinting Cars In Order (Lowercase)")
for (car in cars) {
    println(car.toLowerCase())
} So essentially what we are doing is taking our values in cars and setting each one to a variable named car. We are then going to take the value of car, make it lowercase, and then print it out. Stop Printing After “Ford” Is Printed The last example I want to go through is using a while loop to only print out items until we reach one that has “Ford” in the name. Here is what my solution looks like: println("\nPrinting Cars Until Ford Found")
var fordWasPrinted = false
var index = 0;
while (!fordWasPrinted) {
    val car = cars[index]
    println(car)
    fordWasPrinted = car.toLowerCase().contains("ford")
    index++
} Before we get to the while loop we first setup two variables. We need a condition to keep track of for our loop, for that we declare fordWasPrinted which by default is false. I also define index which will keep track of where we are in our array, again, arrays start out at zero. Now it’s time to enter into the while loop, as long as fordWasPrinted is false it will keep going through the loop. The first thing we do inside of the loop is set car equal to our current item in the cars array. We then print out the car to the console. On the next line we determine if the car contains the word “ford”. We do that by first getting a lowercase string representation of car and then ask if it contains the word “ford”. If it does then it will return true, otherwise it will return false. We are assigning that returned value to fordWasPrinted. Then we increment the value of index and we return to the top of our loop where we check the value of fordWasPrinted. Once that value is true we will exit the loop and complete our program. As a note, if you don’t have Ford in the list, my solution will cause the app to crash. As homework feel free to add some error handling so that the app won’t crash if you omit Ford from the list. So now you can go ahead and run the program and should see that the car list is printed out three times, and each time it should be slightly different. The first time it will just print them out normally, the second time they will be all lowercase, and the third time it will only print out part of the list. Here’s my full solution: fun main(args : Array<String>) {

    val cars = arrayOf(
            "Toyota Camry",
            "Toyota Corolla",
            "Honda Civic",
            "Nissan Altima",
            "Honda Accord",
            "Hyundai Elantra",
            "Nissan Sentra",
            "Ford Fusion",
            "Chevrolet Cruze",
            "Hyundai Sonata",
            "Ford Focus",
            "Mazda MX-5 Miata",
            "Fiat 124 Spider",
            "Subaru BRZ",
            "Toyota 86",
            "Nissan Z",
            "Dodge Challenger",
            "Ford Mustang",
            "Chevrolet Camaro",
            "Audi TT / TTS"
    )

    println("\nPrinting Cars In Order")
    for (index in cars.indices) {
        println(cars[index])
    }

    println("\nPrinting Cars In Order (Lowercase)")
    for (car in cars) {
        println(car.toLowerCase())
    }

    println("\nPrinting Cars Until Ford Found")
    var fordWasPrinted = false
    var index = 0;
    while (!fordWasPrinted) {
        val car = cars[index]
        println(car)
        fordWasPrinted = car.toLowerCase().contains("ford")
        index++
    }

} And that’s all for this lesson. As always if you have any questions or comments feel free to leave a response below. The subject of this article was inspired by a response in the previous article, so I do my best to incorporate feedback in future articles.

Let’s Learn How To Code Using Kotlin — Part 004

A major Nissan auto recall has just been announced, the US National Highway Traffic Safety Administration has indicated. According to , this recall shouldn’t be ignored due to the fact that the issues associated with the campaign may lead to major or even fatal risks. safety advocates The official announcement dropped by US regulators shows that at least 3 million vehicles have been impacted in the United States. The announcement shows that the recalled units include the 2016 and 2017 Nissan Maxima, the 2013 through 2016 Nissan Altima, LEAF, Sentra, and NV200, the 2013 through 2017 Nissan Pathfinder, the 2014 through 2016 Nissan NV200 Taxi, Infiniti QX60 and Q50, the 2014 through 2017 Nissan Rogue, the 2015 and 2016 Nissan Murano, Chevrolet City Express, and the 2013 Infiniti JX35 vehicles. Since these vehicles come with Occupant Classification Systems that may classify an adult passenger as a child, or fail to register that the seat is being used even if it’s occupied, the air bag system may not function correctly in the event of a crash. If that’s the case, the air bag may not deploy while the seat is being occupied by an adult and injuries will ensue. Depending on the impact, the injuries could even be fatal. Consumers with the recalled vehicles will be contacted by the company, but a notification schedule hasn’t been produced yet. If your vehicle is a Chevrolet, General Motors will be contacting you so you learn more about this recall, but if you own one of the Nissan vehicles impacted by this campaign, Nissan will be reaching out to you. Until you’re contacted, you’re urged to reach out personally to manufacturers if you have further questions that haven’t been addressed in the official recall report. For the official recall report, follow . Stay safe and avoid injuries by making sure your recalled vehicles are always promptly fixed. this link

SENTRAX

sentrax.com

-- employees

Since n.d.

COMPANY RANKING

SENTRAX

EVERGREEN INDEX #9263

Representing this company? Click here to claim and customize this page!

Sentrax WIKI

Apply to get your Tech Company News Page live on HackerNoon.com today!

SENTRAX

sentrax.com

-- employees

Since n.d.

COMPANY RANKING

SENTRAX

EVERGREEN INDEX #9263

RELATED COMPANIESRANK

STORIES ABOUT SENTRAX

Representing this company? Click here to claim and customize this page!

Sentrax WIKI

Apply to get your Tech Company News Page live on HackerNoon.com today!