Android Advance Go Back Activities, Intents and Activity lifecycle views 12:00 The apps that we had created till now had only one activity i.e. a screen. But if you have a look at the apps that you use on a daily basis, you will realize that none of the apps have just a single activity. Let us take the example of whatsapp. When you open whatsapp, you see a list of people to whom you have sent messages to or from whom you have received messages. When you press the name of the person then you get to see the details of the conversation that you have had with them. In an app for a bank, you see the log in screen on the first activity. If the login is successful then the welcome page is displayed. Activities, Intents and Activity lifecycle Showing User Name in login page. Creating Buttons in app. Creating a Function for Buttons. Creating Conditional Function.