Video: Create New Activity – Developing Android Apps
You're going to use Android Studio to create the DetailActivity from the Blank Activity with Fragment template. The template asks for the hierarchical parent of DetailActivity, which defines the UP button noted by the app icon, and a left-pointing carat here. But what does "up" mean? If you mapped out a hierarchy of all screens in the Sunshine app, the root of the tree would be the MainActivity, and it's child would be the DetailActivity. So, the UP goes to the MainActivity. While the BACK button can achieve the same effect, it can also bring you back home, or to another app, depending on your history of screens. UP will always navigate you within the same app to the parent, regardless of how you arrived at this screen. Create the detail activity now, and look at how the activity is declared in the Android manifest file.