Android view and viewgroup

Difference Between View and ViewGroup in Android

In Android Layout is used to describe the user interface for an app or activity, and it stores the UI elements that will be visible to the user. An android app’s user interface is made up of a series of View and ViewGroup elements. In most cases, android apps will have one or more operations, each of which is a single screen of the app. Multiple UI components will be present in the operations, and those UI components will be instances of the View and ViewGroup subclasses. Generally, the android apps will contain one or more activities and each activity is one screen of the app. The activities will contain multiple UI components and those UI components are the instances of View and ViewGroup subclasses. In Android apps, the two very central classes are the Android View class and ViewGroup class. One or more tasks can be found in an Android app. A screen in an Android operation is identical to the windows in a desktop application. GUI components may be used in an operation. View or ViewGroup subclasses are used to build the GUI elements.

View is a basic building block of UI (User Interface) in android. A view is a small rectangular box that responds to user inputs. Eg: EditText, Button, CheckBox, etc. ViewGroup is an invisible container of other views (child views) and other ViewGroup. Eg: LinearLayout is a ViewGroup that can contain other views in it. ViewGroup is a special kind of view that is extended from View as its base class. ViewGroup is the base class for layouts. As the name states View is singular and the group of Views is the ViewGroup. In simple terms, a view is a user interface feature that we interact with when we use an app, such as a button, editing text and images, and so on. Android.view has a child class called View. Observe While the View group is the container that houses all of these views as well as many other ViewGroup such as linear or Frame Layout. For example, if we design and use the LinearLayout as the root feature, our main layout would be the LinearLayout. Within it, we can add another view category (i.e. another LinearLayout) and several other views such as buttons or TextViews.

View

The View class is the base class or we can say that it is the superclass for all the GUI components in android. For example, the EditText class is used to accept the input from users in android apps, which is a subclass of View, and another example of the TextView class which is used to display text labels in Android apps is also a subclass of View.

Or the other definition,

View refer to the android.view.View class, which is the base class of all UI classes. android.view.View class is the root of the UI class hierarchy. So from an object point of view, all UI objects are View objects. Following are some of the common View subclasses that will be used in android applications.

• TextView
• EditText
• ImageView
• RadioButton
• Button
• ImageButton
• CheckBox
• DatePicker
• Spinner
• ProgressBar and etc.

These are some of the view subclass available in android.

ViewGroup

The ViewGroup class is a subclass of the View class. And also it will act as a base class for layouts and layouts parameters. The ViewGroup will provide an invisible container to hold other Views or ViewGroups and to define the layout properties. For example, Linear Layout is the ViewGroup that contains UI controls like Button, TextView, etc., and other layouts also. ViewGroup Refer to the android.view.ViewGroup class, which is the base class of some special UI classes that can contain other View objects as children. Since ViewGroup objects are also View objects, multiple ViewGroup objects and View objects can be organized into an object tree to build a complex UI structure. Following are the commonly used ViewGroup subclasses used in android applications.

• FrameLayout
• WebView
• ListView
• GridView
• LinearLayout
• RelativeLayout
• TableLayout and many more.

The ViewGroup subclasses listed above group View instances together and takes care of their layout. For instance, the LinearLayout will render the components after each other either horizontally or vertically.

Difference Table

View	ViewGroup
View is a simple rectangle box that responds to the user’s actions.	ViewGroup is the invisible container. It holds View and ViewGroup
View is the SuperClass of All component like TextView, EditText, ListView, etc	ViewGroup is a collection of Views(TextView, EditText, ListView, etc..), somewhat like a container.
A View object is a component of the user interface (UI) like a button or a text box, and it’s also called a widget.	A ViewGroup object is a layout, that is, a container of other ViewGroup objects (layouts) and View objects (widgets)
Examples are EditText, Button, CheckBox, etc.	For example, LinearLayout is the ViewGroup that contains Button(View), and other Layouts also.
View refers to the android.view.View class	ViewGroup refers to the android.view.ViewGroup class
android.view.View which is the base class of all UI classes.	ViewGroup is the base class for Layouts.

So, these all are the basic key difference between the View class and Viewgroup class in Android.

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Разница между View и ViewGroup в Android

В чем разница между View и ViewGroup в Android-программировании?

Посмотреть

1. View объекты – это основные строительные элементы элементов пользовательского интерфейса (UI) в Android.
2. View представляет собой простой прямоугольник, который реагирует на действия пользователя.
3. Примерами являются EditText , Button , CheckBox т. Д.
4. View относится к классу android.view.View , который является базовым классом для всех классов пользовательского интерфейса.

ViewGroup

1. ViewGroup – невидимый контейнер. Он содержит View и ViewGroup
2. Например, LinearLayout – это ViewGroup которая содержит кнопку (вид) и другие макеты.
3. ViewGroup – это базовый класс для макетов.

Ниже изображен ответ . Не считайте это слишком сложным.

1. ViewGroup – это специальное представление, которое может содержать другие представления (называемые ViewGroup .) Группа просмотра – это базовый класс для макетов и представлений. Этот класс также определяет класс ViewGroup.LayoutParams который служит базовым классом для параметров макетов.

Класс View представляет собой основной строительный блок для компонентов пользовательского интерфейса. Вид занимает прямоугольную область на экране и отвечает за рисование и обработку событий. Вид – это базовый класс для виджетов, которые используются для создания компонентов интерактивного интерфейса (кнопки, текстовые поля и т. Д.).

1. Пример: ViewGroup (LinearLayout), View (TextView)

View – это основной строительный блок UI (User Interface) в android. Вид представляет собой небольшой прямоугольный блок, который реагирует на пользовательские входы. Например: EditText , Button , CheckBox и т. Д.

ViewGroup – невидимый контейнер других представлений (дочерние представления) и другие группы представлений. Например: LinearLayout – это группа представлений, которая может содержать в себе другие представления.

ViewGroup – это особый вид вида, который расширяется из представления в качестве базового класса. ViewGroup – это базовый класс для макетов.

ViewGroup состояния имен View являются единственными, а группа Views – ViewGroup .

Viewgroup наследует свойства просмотров и делает больше с другими представлениями и группой просмотра.

ViewGroup сама представляет собой представление, которое работает как контейнер для других представлений. Он расширяет функциональность класса View , чтобы обеспечить эффективные способы компоновки дочерних представлений для ex. LinearLayout – это ViewGroup которая позволяет вам определить ориентацию, в которой вы хотите укладывать детские представления, это все, что вам нужно сделать, и LinearLayout позаботится обо всем остальном.

• Обратитесь к классу android.view.View , который является базовым классом для всех классов пользовательского интерфейса. Класс android.view.View – это корень иерархии классов пользовательского интерфейса. Таким образом, с объектной точки зрения все объекты пользовательского интерфейса являются объектами View.

• Обратитесь к классу android.view.ViewGroup , который является базовым классом некоторых специальных классов пользовательского интерфейса, которые могут содержать другие объекты View как дети. Так ViewGroup объекты ViewGroup также являются объектами View, для создания сложной структуры пользовательского интерфейса могут быть организованы несколько объектов ViewGroup объекты View в дереве объектов.

В ViewGroup вы можете добавить еще один View s в качестве дочернего. ViewGroup – это базовый класс для макетов и контейнеров.

View – это класс SuperClass для всех, такой как TextView, EditText, ListView, т. Д., В то время как ViewGroup – это ViewGroup представлений (TextView, EditText, ListView, etc..) , Несколько напоминающая контейнер.

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Android View and ViewGroup with Examples

In android, Layout is used to define the user interface for an app or activity and it will hold the UI elements that will appear to the user.

The user interface in an android app is made with a collection of View and ViewGroup objects. Generally, the android apps will contain one or more activities and each activity is a one screen of app. The activities will contain a multiple UI components and those UI components are the instances of View and ViewGroup subclasses.

The user interface in an android app is made with a collection of View and ViewGroup objects. Generally, the android apps will contain one or more activities and each activity is a one screen of the app. The activities will contain multiple UI components and those UI components are the instances of View and ViewGroup subclasses.

Android View

The View is a base class for all UI components in android. For example, the EditText class is used to accept the input from users in android apps, which is a subclass of View .

Following are the some of common View subclasses that will be used in android applications.

Like these we have many View subclasses available in android.

Android ViewGroup

The ViewGroup is a subclass of View and it will act as a base class for layouts and layouts parameters. The ViewGroup will provide an invisible containers to hold other Views or ViewGroups and to define the layout properties.

For example, Linear Layout is the ViewGroup that contains a UI controls like button, textview, etc. and other layouts also.

Following are the commonly used ViewGroup subclasses in android applications.

Both View and ViewGroup subclasses together will play a key role to create a layouts in android applications.

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Introduction to Android Views and ViewGroups

All the interaction of a user with the Android application is through the user interface(UI), hence it is very important to understand the basics about the User Interface of an android application. Here in this tutorial, we are going to cover about various Views and ViewGroups and will try to explain how they can be used to design the User Interface of an android application.

Views

View is the basic building block of UI(User Interface) in android. View refers to the android.view.View class, which is the super class for all the GUI components like TextView , ImageView , Button etc.

View class extends Object class and implements Drawable.Callback , KeyEvent.Callback and AccessibilityEventSource .

View can be considered as a rectangle on the screen that shows some type of content. It can be an image, a piece of text, a button or anything that an android application can display. The rectangle here is actually invisible, but every view occupies a rectangle shape.

The question that might be bothering you would be , what can be the size of this rectangle?

The answer is either we can set it manually, by specifying the exact size(with proper units) or by using some predefined values. These predefined values are match_parent and wrap_content .

match_parent means it will occupy the complete space available on the display of the device. Whereas, wrap_content means it will occupy only that much space as required for its content to display.

A View is also known as Widget in Android. Any visual(that we can see on screen) and interactive(with which user can interact with) is called a Widget.

XML syntax for creating a View

Now, as we have explained earlier as well, to draw anything in your android application, you will have to sepcify it in the design XML files. And to add functionality we will create Java files.

Every view in XML has the following format:

• It always start with an angle bracket, followed by the View name. We will introduce you to various types of Views very soon.
• Then we write attributes that will define how that view will look on the screen of the application along with a value for the attribute. Each view has its own attributes which we will discuss in the next few tutorials which will cover various typs of views.
• In the end, it is closed by/>

So, every View subclass needs to follow this format so that it can appear on the screen of the app. And this format is nothing but default XML style. Right!

There are two attributes that are necessary for every View . These are: android:layout_height and android:layout_width .

These attributes define the size of the invisible rectangle that a view makes. Using these attributes we can easily control the size for every view in our android application.

Apart from the above mentioned attributes, attributes like gravity , layout_gravity , padding and margin are some other commonly used attributes.

Most commonly used Android View classes

Here we have some of the most commonly used android View classes:

Programmatic and Declarative Approach

To create/define a View or a ViewGroup in your android application, there are two possible ways:

The Programmatic Approach: In this we define/create our Views in the Java source file. We will learn about this approach in details later, as of now here is a sample code to add a Button to our view.

So addView() is the function used to add any View to the UI and setLayoutParams() function is used to set the various attributes.

The Declarative Approach: In this we define the View and ViewGroups directly in the design XML files, like we will be doing in the next couple of tutorials where we will study about various commonly used views.

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