Activities

Activities are a fundamental concept in Android development. They are the building blocks of an Android application and represent a single screen with a user interface. Activities can be used to display data, collect user input, and navigate between different screens in an application.

What are Activities?

Activities are classes that extend the Activity class in the Android SDK. They define the layout of a screen and the behavior of the screen when it is displayed. Activities can be created programmatically or by using the Android Studio IDE.

When an activity is created, it is added to the activity stack. The activity stack is a stack of all the activities that have been created in an application. When a new activity is created, it is pushed onto the activity stack and becomes the current activity. When an activity is finished, it is popped off the activity stack and the previous activity becomes the current activity.

Activity Lifecycle

The activity lifecycle is a series of methods that are called when an activity is created, started, resumed, paused, stopped, and destroyed. These methods allow you to manage the state of an activity as it transitions through different states.

The following is a brief overview of the activity lifecycle:

• onCreate(): This method is called when an activity is first created. It is used to initialize the activity and create its layout.
• onStart(): This method is called when an activity is started. It is used to start any tasks that need to be performed when the activity is visible to the user.
• onResume(): This method is called when an activity is resumed. It is used to resume any tasks that were paused when the activity was paused.
• onPause(): This method is called when an activity is paused. It is used to pause any tasks that are currently being performed by the activity.
• onStop(): This method is called when an activity is stopped. It is used to stop any tasks that are currently being performed by the activity and to release any resources that are no longer needed.
• onDestroy(): This method is called when an activity is destroyed. It is used to clean up any resources that were allocated by the activity.

Types of Activities

There are many different types of activities that can be created in an Android application. Some of the most common types of activities include:

• Launcher activities: Launcher activities are the activities that are displayed when an application is launched. They typically contain a list of options or a menu that allows the user to navigate to other activities in the application.
• Navigational activities: Navigational activities are used to navigate between different screens in an application. They typically contain a list of options or a menu that allows the user to select a different screen to display.
• Data entry activities: Data entry activities are used to collect user input. They typically contain a form that allows the user to enter data.
• Display activities: Display activities are used to display data to the user. They typically contain a list of data or a chart.

Benefits of Using Activities

There are many benefits of using activities in Android development. Some of the benefits include:

• Modularity: Activities are modular, which makes it easy to reuse them in different applications.
• Flexibility: Activities can be used to create a wide variety of different types of applications.
• Testability: Activities can be easily tested, which makes it easy to ensure that they are working correctly.

Online Courses

There are many online courses that can help you learn about activities. These courses can teach you the basics of activities, how to create and use different types of activities, and how to manage the activity lifecycle. By taking an online course, you can learn about activities at your own pace and in your own time.

Some of the skills and knowledge that you can gain from online courses about activities include:

• How to create a new activity
• How to use the activity lifecycle
• How to navigate between activities
• How to use activities to collect user input
• How to use activities to display data

Online courses can be a helpful learning tool, but they are not enough to fully understand activities. To fully understand activities, you need to practice creating and using them in your own applications.

If you are interested in learning more about activities, I encourage you to take an online course about them. There are many great courses available that can help you learn the basics of activities and how to use them in your own applications.