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Time calc app android how to#
Time calc app android for android#
Time calc app android android#
Time calc app android code#

Open MainActivity.kt ( app > java > MainActivity).

Instead of calling findViewById() for each View in your app, you'll create and initialize a binding object once. It's one of the first things called when your app starts and the MainActivity is initialized. In earlier codelabs, you saw the onCreate() method in the MainActivity class.

Time calc app android android#

Note the message Gradle files have changed since last project sync.Īfter a few moments, you should see a message at the bottom of the Android Studio window, Gradle sync finished.

In the android section, add the following lines:.

Open the app's adle file ( Gradle Scripts > adle (Module: Tip_Time.app) ).

Time calc app android code#

You'll need to enable view binding for your app in Gradle, and make some code changes. With a little more work up front, view binding makes it much easier and faster to call methods on the views in your UI.

This approach works, but as you add more views to your app and the UI becomes more complex, using findViewById() can become cumbersome.įor convenience, Android also provides a feature called view binding. The Android framework provides a method, findViewById(), that does exactly what you need-given the ID of a View, return a reference to it. You may recall from earlier codelabs that your code needs to find a reference to a View like a Button or TextView before your code can call methods on the View or access its attributes. In order to calculate the tip, your code will need to access all of the UI elements to read the input from the user. Note: You can also write Android apps in the Java programming language. There are other folders and files involved in building your app, but these are the main ones you'll work with for this codelab and the following ones. It also installs your app in the emulator or physical device and controls its execution. Whenever you change code, add a resource, or make other changes to your app, Gradle figures out what has changed and takes the necessary steps to rebuild your app. Gradle is the automated build system used by Android Studio. strings.xml - contains string resources for your Android app.activity_main.xml - layout file for your Android app.MainActivity - class where all of the Kotlin code for the tip calculator logic will go.java folder for Kotlin files (or Java files).If it's not already selected, choose the Android view from the dropdown.If the Project window isn't showing, select the Project tab on the left side of Android Studio.Open the Tip Time project in Android Studio.Before making changes to the app, it's good to learn your way around. That's where this codelab picks up.Īn app project in your IDE consists of a number of pieces, including Kotlin code, XML layouts, and other resources like strings and images. The tip amount is displayed in a TextView, and finally a Calculate Button will tell the app to get the data from the other fields and calculate the tip amount. A list of RadioButtons lets the user select the tip percentage, and a Switch allows the user to choose whether the tip should be rounded up or not. The Cost of Service EditText allows the user to enter the cost of the service. There's a Calculate button, but it doesn't work yet. The Tip Time app from the last codelab has all the UI needed for a tip calculator, but no code to calculate the tip. Starter code for the Tip Time app that contains the layout for a tip calculator.A computer with the latest stable version of Android Studio installed.A tip calculator app with a working Calculate button.

Time calc app android how to#

How to use Logcat in Android Studio to find problems in your app.

How to use string parameters to dynamically create strings.

How to work with decimal numbers in Kotlin with the Double data type.

How to use view binding instead of findViewById() to more easily write code that interacts with views.

How to read in values from the UI into your code and manipulate them.

How to run an Android app from Android Studio in the emulator or on a device.

Time calc app android for android#

The code from the Create XML layouts for Android codelab.

In this codelab, you will be writing code for the tip calculator to go with the UI you created in the previous codelab, Create XML layouts for Android.