File is a file on the filesystem. Class is a Java class. Activity is a specific java class commonly used in Android. 1) Class is Blueprint of object and you will create as many object you want from same class.
What is class and activity android?
You implement an activity as a subclass of the Activity class. An activity provides the window in which the app draws its UI. This window typically fills the screen, but may be smaller than the screen and float on top of other windows. Generally, one activity implements one screen in an app.
What is the difference between context and activity in Android?
2 Answers. An Application context lasts, as long as your app is alive, while the Activity context dies with your Activity (it is not valid after onDestroy of that Activity). So if you need the Context across Activities (i.e. in a Singleton) you will be better off using an Application context.
Is activity a Java class?
An activity represents a single screen with a user interface just like window or frame of Java. Android activity is the subclass of ContextThemeWrapper class.
Is activity a view in Android?
The Activity and Controller are still part of the view layer, but the distinction between controller and view is much more clear. Activities and Fragments are even referred to as UI controllers in the documentation for the new Android Architecture Components.
What is the use of context in Android?
It’s an abstract class whose implementation is provided by the Android system. Context allows access to application-specific resources and classes, as well as calls for application-level operations such as launching activities, broadcasting and receiving intents, etc.
What are the main two types of thread in Android?
Android has four basic types of threads. You’ll see other documentation talk about even more, but we’re going to focus on Thread , Handler , AsyncTask , and something called HandlerThread . You may have heard HandlerThread just called the “Handler/Looper combo”.
What is the use of application class in Android?
The Application class in Android is the base class within an Android app that contains all other components such as activities and services. The Application class, or any subclass of the Application class, is instantiated before any other class when the process for your application/package is created.
How do you call a class in Android activity?
public class MainActivity extends AppCompatActivity { // Instance of AnotherClass for future use private AnotherClass anotherClass; @Override protected void onCreate(Bundle savedInstanceState) { // Create new instance of AnotherClass and // pass instance of MainActivity by “this” anotherClass = new AnotherClass(this); …
How do you create an activity?
To create the second activity, follow these steps:
- In the Project window, right-click the app folder and select New > Activity > Empty Activity.
- In the Configure Activity window, enter “DisplayMessageActivity” for Activity Name. Leave all other properties set to their defaults and click Finish.