![]() ![]() Since the Button is sitting within a ConstraintLayout, you must set vertical and horizontal constraints to position it. Notice an error that the Button is not constrained.Below the Palette in the Component Tree, verify that the Button and TextView are listed under the ConstraintLayout (as children of the ConstraintLayout).Drag a Button from the Palette onto the Design view, positioning it below the "Hello World" TextView.Note: Like in a family tree, in a view hierarchy, parent views can themselves be child views, and child views can be parents to other children. In the case of your app, the TextView and Button would be considered children of the parent ConstraintLayout.Īdd a Button as a child of the existing ConstraintLayout in your app. When there are Views within a ViewGroup, the Views are considered children of the parent ViewGroup. The TextView and the Button will be located within a ConstraintLayout, which is a type of ViewGroup. In this task, you add a Button below the "Hello World" TextView. A Button is a user interface (UI) element in Android that the user can tap to perform an action. You should see the Layout Editor, with only the "Hello World" TextView in the center of the app. In the Project window, double-click activity_main.xml ( app > res > layout > activity_main.xml) to open it.Run the new app and it should look like this.Call the app "Dice Roller", with a minimum API level of 19 (KitKat).In Create New Project, create a new Kotlin project using the Empty Activity template.If you already have an existing project open in Android Studio, go to File > New > New Project.Here is what the app will look like when you have completed this codelab. A computer with Android Studio installed.A Dice Roller Android app that has a Button to roll a dice and updates the text on the screen with the result of the roll.How to update the contents of a TextView while the app is running. ![]()
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