View is a basic building block of UI (User Interface) in android. A view is a small rectangular box which responds to user inputs. Eg: EditText , Button , CheckBox , etc.. ViewGroup is a invisible container of other views (child views) and other viewgroups.
What are view and ViewGroup classes in Android?
View is the base class for widgets, which are used to create interactive UI components like buttons, text fields, etc. The ViewGroup is a subclass of View and provides invisible container that hold other Views or other ViewGroups and define their layout properties.
What is Android ViewGroup?
A ViewGroup is a special view that can contain other views. The ViewGroup is the base class for Layouts in android, like LinearLayout , RelativeLayout , FrameLayout etc. In other words, ViewGroup is generally used to define the layout in which views(widgets) will be set/arranged/listed on the android screen.
What is the main purpose of ViewGroup?
What is the main purpose of a ViewGroup? It groups together the most common views that developers use in Android apps. It serves as a container for View objects, and is responsible for arranging the View objects within it. It is required to make a view interactive as a way to group TextViews on a screen.
What are the views in Android?
Here we have some of the most commonly used android View classes:
- TextView.
- EditText.
- Button.
- ImageView.
- ImageButton.
- CheckBox.
- RadioButton.
- ListView.
What is the use of ConstraintLayout in Android?
Android Constraint Layout Overview
Android ConstraintLayout is used to define a layout by assigning constraints for every child view/widget relative to other views present. A ConstraintLayout is similar to a RelativeLayout, but with more power.
Where are layouts placed in Android?
In Android, an XML-based layout is a file that defines the different widgets to be used in the UI and the relations between those widgets and their containers. Android treats the layout files as resources. Hence the layouts are kept in the folder reslayout.
What is Clipchildren?
2, can through android:layout_gravity control over how the part of the display. … 3, Android:clipchildren meaning: whether to limit the child view within its scope.
What is intent used for in Android?
Intents are used to signal to the Android system that a certain event has occurred. Intents often describe the action which should be performed and provide data upon which such an action should be done. For example, your application can start a browser component for a certain URL via an intent.
What is foreground activity in Android?
A foreground service performs some operation that is noticeable to the user. For example, an audio app would use a foreground service to play an audio track. Foreground services must display a Notification. Foreground services continue running even when the user isn’t interacting with the app.
What is the use of linear layout in Android?
LinearLayout is a view group that aligns all children in a single direction, vertically or horizontally. You can specify the layout direction with the android:orientation attribute. Note: For better performance and tooling support, you should instead build your layout with ConstraintLayout.
How do you kill an activity?
Launch your application, open some new Activity, do some work. Hit the Home button (application will be in the background, in stopped state). Kill the Application — easiest way is to just click the red “stop” button in Android Studio. Return back to your application (launch from Recent apps).
What is the fragment life cycle in Android?
A fragment can be used in multiple activities. Fragment life cycle is closely related to the life cycle of its host activity which means when the activity is paused, all the fragments available in the activity will also be stopped. A fragment can implement a behaviour that has no user interface component.
What is the use of findViewById in Android?
findViewById is the method that finds the View by the ID it is given. So findViewById(R. id. myName) finds the View with name ‘myName’.
What is the use of OnClickListener in Android?
In Android, the OnClickListener() interface has an onClick(View v) method that is called when the view (component) is clicked. The code for a component’s functionality is written inside this method, and the listener is set using the setOnClickListener() method.
What are the 4 types of app components?
There are four different types of app components:
- Activities.
- Services.
- Broadcast receivers.
- Content providers.