Running your first Android application

We made our first screen and defined some specifics for the application itself. To be sure that what we did so far is ok, we do the build and run our application. We will run the completeDebug build variant. If you forgot how to switch to this build variant, we will remind you. Open Android Studio and the Journaler project. Open the Build Variants pane by clicking on the Build Variants pane on the left side of the Android Studio window or by choosing View |Tool Windows | Build Variants. The Build Variants pane will appear. Choose completeDebug from the drop-down list, as shown in the screenshot:

We will use this Build Variant as our main build variant for the try out execution, and for production build, we will use the completeDebug build variant. After we choose Build Variant from the drop-down list, it takes some time for Gradle to build the chosen variant.

We will run our application now. We will do it on an emulator first and then on a real live device. Start your emulator instance by opening the AVD Manager. We will open it by clicking on the AVD Manager icon. It is the fastest way to open it. Double-click on the AVD instance. It will take some time until your emulator is ready. Emulator performs Android system boot and then it loads a default application launcher.

Your emulator is booted and ready to run the application. In order to run the application, click on the Run icon or navigate to Run | Run 'app'.

When an application runs, a dialog box for Select Deployment Target appears. In case you have multiple instances on which an application can run, you can choose one of them as shown in the following screenshot:

Pick your deployment target and click on OK. In case you want to remember your selection, check the Use same selection for future launches selection. It takes some time for the application to run, but after a few seconds, your application appears!