Here we can see the changes in the coding, while using Java and Kotlin.
In Kotlin, the following code is used: val t: TextView = findViewById(R.id.textview) as TextView The above code is used to set a text to the TextView element, with the ID ‘textview’ added to the layout file, in Java coding. T=(TextView) findViewById(R.id.textview) In normal Java coding, we need the following code to refer to a TextView, and for setting a text to the above added TextView: TextView t We can also view many other properties, such as setting size, giving colour, etc, by selecting the ‘View all properties’ link at the bottom of the Properties window. This ID is used to uniquely identify the particular element in our Java/Kotlin code. The most important property is the ID, so provide a suitable name, or rather, set the ID value as ‘textview’ itself for easy identification. To the right, we have the Properties window, where we can make property changes to the selected TextView. In Figure 5, on the left, we have the Palette window, where we can select and add more widgets to the application screen. Next, select the TextView from the Component Tree window (Figure 5). Switch to the ‘Design’ section from the TextView (this can be changed at the bottom part of the displayed window, containing code). Here, we can see that a TextView has already been added to the layout file. Let’s now open the layout file, which is located at app > res > layout > activity_main.xml (the default name). Here we need a TextView, which we will refer to and set a text to it. Let’s create our simple application, which will print ‘Welcome to OSFY’ on the screen. Figure 3: Differences between the Java and the Kotlin class Figure 4: Location of the layout file Kotlin is a simple and easy-to-code language, allowing users to skip the headache of verbosity. We can see a considerable difference in the Java and Kotlin syntax. Unlike Java, Kotlin requires explicit annotations for overridable members for overrides. ‘override’ becomes part of the onCreate function and the function syntax is changed to ‘fun onCreate’ in Kotlin. In Kotlin, the declaration of a variable name is followed by a ‘:’, after which the datatype is specified.ģ. extends AppCompatActivity is changed to: AppCompatActivity(). The following differences can be noted:ġ. For other versions, the user needs to convert the existing Java class to Kotlin, by opening the MainActivity.java file, and then selecting Code > Convert Java file to Kotlin file (Figure 2).įigure 3 shows the differences between Java class and Kotlin class. Checking the box will enable Kotlin, and this is the starting activity - the MainActivity (default name) named MainActivity.kt. The slide asking for the project’s name will have an option underneath, ‘ Include Kotlin Support’. Now, add the following line to the adle (Module: app) file, as the second line, followed by the plugin: apply plugin: ‘kotlin-android’ Figure 1: Adding Kotlin to Android Studio Figure 2: Converting Java to KotlinĪndroid Studio 3.0 users can directly select Kotlin as their default language while creating a new project as usual, select File > New > New Project. classpath “:kotlin-gradle-plugin:$kotlin_version”Ĭlasspath “:kotlin-android-extensions:$kotlin_version”Īlso add the Kotlin version into the buildscript section, as follows: ext.kotlin_version = ‘1.1.x’ Now, if the Android Studio version is not 3.0, we need to add the following code into the adle (Project: MyApplication) file (located at the bottom of the left side of the Project window, inside Gradle Scripts), under the dependencies section.
Hit Install to add Kotlin to your Android Studio.Select Plugins and search for Kotlin (Figure 1).For all other versions below 3.0, the user needs to install Kotlin manually as follows:
I have already discuss how to send sms and how to get location.ĩ.Android Studio 3.0 comes with pre-installed Kotlin. This application can be used to get message of location when you start your mobile and it can be used to catch thief because when anyone steal your mobile and open your mobile than a message of thief's location will send to your given number. This application will show how to start an activity when we restart our mobile. Android source code get Sim number on mobile restart:. This application is same as above example but we have used MySQL and PHP instead of SQLite to store and fetch data.Ĩ. Android source code for Login,Register page with MySQL and PHP:. Simple SQLite example are also available here:- How to use SQLite database in android.ħ.
We used hide and show image in password field so we can hide and show entered password. In this application, there are three pages Login,Registration and welcome pages.