Android 中 View 与 ViewGroup 的区别

in ViewGroup you can add some other Views as child. ViewGroup is the base class for layouts and view containers.

Viewgroup inherits properties of views and does more with other views and viewgroup.

See the Android API: http://developer.android.com/reference/android/view/ViewGroup.html

View is the SuperClass of All component like TextView, EditText, ListView, etc.. while ViewGroup is Collection of Views(TextView, EditText, ListView, etc..), somewhat like container.

1. A ViewGroup is a special view that can contain other views (called children.) The view group is the base class for layouts and views containers. This class also defines the ViewGroup.LayoutParams class which serves as the base class for layouts parameters.

   View class represents the basic building block for user interface components. A View occupies a rectangular area on the screen and is responsible for drawing and event handling. View is the base class for widgets, which are used to create interactive UI components (buttons, text fields, etc.).

2. Example : ViewGroup (LinearLayout), View (TextView)

Reference

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. Eg: LinearLayout is a viewgroup which can contain other views in it.

ViewGroup is a special kind of view which is extended from View as its base class. ViewGroup is the base class for layouts.

as name states View is singular and the group of Views is the ViewGroup.

more info: http://www.herongyang.com/Android/View-ViewGroup-Layout-and-Widget.html

ViewGroup is itself a View that works as a container for other views. It extends the functionality of View class in order to provide efficient ways to layout the child views.

For example, LinearLayout is a ViewGroup that lets you define the orientation in which you want child views to be laid, that's all you need to do and LinearLayout will take care of the rest.

Below image is the answer. Don't take it too complex.

View

1. View objects are the basic building blocks of User Interface(UI) elements in Android.
2. View is a simple rectangle box which responds to the user's actions.
3. Examples are EditText, Button, CheckBox etc..
4. View refers to the android.view.View class, which is the base class of all UI classes.

ViewGroup

1. ViewGroup is the invisible container. It holds View and ViewGroup
2. For example, LinearLayout is the ViewGroup that contains Button(View), and other Layouts also.
3. ViewGroup is the base class for Layouts.

A ViewGroup describes the layout of the Views in its group. The two basic examples of ViewGroups are LinearLayout and RelativeLayout. Breaking LinearLayout even further, you can have either Vertical LinearLayout or Horizontal LinearLayout. If you choose Vertical LinearLayout, your Views will stack vertically on your screen. The two most basic examples of Views are TextView and Button. Thus, if you have a ViewGroup of Vertical LinearLayout, your Views (e.g. TextViews and Buttons) would line up vertically down your screen.

When the other posters show nested ViewGroups, what they mean is, for example, one of the rows in my Vertical LinearLayout might actually, at the lower level, be several items arranged horizontally. In that case, I'd have a Horizontal LinearLayout as one of the children of my top level Vertical LinearLayout.

Example of Nested ViewGroups:
Parent ViewGroup = Vertical LinearLayout

Row1: TextView1
Row2: Button1
Row3: Image TextView2 Button2 <-- Horizontal Linear nested in Vertical Linear
Row4: TextView3
Row5: Button3

A View object is a component of the user interface (UI) like a button or a text box, and it's also called widget.

A ViewGroup object is a layout, that is, a container of other ViewGroup objects (layouts) and View objects (widgets). It's possible to have a layout inside another layout. It's called nested layout but it can increase the time needed to draw the user interface.

The user interface for an app is built using a hierarchy of ViewGroup and View objects. In Android Studio it is possible to use the Component Tree window to visualise this hierarchy.

The Layout Editor in Android Studio can be used to drag and drop View objects (widgets) in the layout. It simplifies the creation of a layout.

In simple words View is the UI element which we interact with when we use an app,like button,edit text and image etc.View is the child class of Android.view.View While View group is the container which contains all these views inside it in addition to several othe viewgroups like linear or Frame Layout etc. Example if we design & take the root element as Linear layout now our main layout is linear layout inside it we can take another view group (i.e another Linear layout) & many other views like buttons or textview etc.