What is the use of adapter view in Android?
Adapter View in Android An Adapter View displays the set of data in the form of List or Grid provided by the Adapter. It has the capability to display a large number of items on the User Interface efficiently. An Android Adapter is responsible for taking the data from the source and put it in the AdapterView.
What is the difference between adapter and adapterview?
Note: Adapter is only responsible for taking the data from a data source and converting it into View and then passing it to the AdapterView. Thus, it is used to manage the data.
What is an adapter in Android SDK?
Android SDK also provides some ready-to-use adapter classes, such as ArrayAdapter, SimpleAdapter etc. What is an Adapter View? An Adapter View can be used to display large sets of data efficiently in form of List or Grid etc, provided to it by an Adapter.
What are the advantages of using adapters in Android?
It has the capability to display a large number of items on the User Interface efficiently. An Android Adapter is responsible for taking the data from the source and put it in the AdapterView. And it is the responsibility of AdapterView to display the data. Adaptors help us make the user interface interactive and friendly to use.
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What is difference between adapter and AdapterView?
An Adapter is responsible for creating and binding data to views. An Adapter isn't an actual view, but instead produces them. An AdapterView is a ViewGroup that gets its child views from an Adapter . E.g. a ListView has a child view for each row in its list.
What can be used to provide views for an AdapterView?
See ListView , GridView , Spinner and Gallery for commonly used subclasses of AdapterView.
What does an ArrayAdapter do?
You can use this adapter to provide views for an AdapterView , Returns a view for each object in a collection of data objects you provide, and can be used with list-based user interface widgets such as ListView or Spinner .
What is custom adapter in android?
In Android, Adapter is a bridge between UI component and data source that helps us to fill data in UI component. It holds the data and send the data to an Adapter view then view can takes the data from the adapter view and shows the data on different views like as ListView, GridView, Spinner etc.
What is an AdapterView?
AdapterView is a ViewGroup that displays items loaded into an adapter. The most common type of adapter comes from an array-based data source.
What are types of adapters in Android?
Android provides several subclasses of Adapter that are useful for retrieving different kinds of data and building views for an AdapterView ( i.e. ListView or GridView). The common adapters are ArrayAdapter,Base Adapter, CursorAdapter, SimpleCursorAdapter,SpinnerAdapter and WrapperListAdapter.
What is notifyDataSetChanged in Android?
notifyDataSetChanged. Notifies the attached observers that the underlying data has been changed and any View reflecting the data set should refresh itself.
What is ArrayAdapter and BaseAdapter?
Here is the difference: BaseAdapter is a very generic adapter that allows you to do pretty much whatever you want. However, you have to do a bit more coding yourself to get it working. ArrayAdapter is a more complete implementation that works well for data in arrays or ArrayList s.
What is simple_list_item_1?
layout. simple_list_item_1 , which is a layout built into Android that provides standard appearance for text in a list, and an ArrayList called restaurants (not seen here).
What is a ViewHolder in android?
A ViewHolder describes an item view and metadata about its place within the RecyclerView. Adapter implementations should subclass ViewHolder and add fields for caching potentially expensive findViewById results.
What is an activity in android?
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 adapter in android with example?
In Android, whenever we want to bind some data which we get from any data source (e.g. ArrayList, HashMap, SQLite, etc.) with a UI component(e.g. ListView, GridView, etc.) then Adapter comes into the picture. Basically Adapter acts as a bridge between the UI component and data sources.
How do you animate a view?
You can use the view animation system to perform tweened animation on Views. Tween animation calculates the animation with information such as the start point, end point, size, rotation, and other common aspects of an animation.
What parameters does ArrayAdapter take?
Parameterscontext: It is used to pass the reference of the current class. ... resource: It is used to set the layout file(. ... textViewResourceId: It is used to set the TextView where you want to display the text data. ... objects: These are the array object which is used to set the array element into the TextView.More items...•
What is view in mobile application development?
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.
How do you use the recycler view?
Using a RecyclerView has the following key steps:Define a model class to use as the data source.Add a RecyclerView to your activity to display the items.Create a custom row layout XML file to visualize the item.Create a RecyclerView. ... Bind the adapter to the data source to populate the RecyclerView.
What is view hierarchy?
Called by the view hierarchy when the content insets for a window have changed, to allow it to adjust its content to fit within those windows.
What is live region mode?
Live region mode specifying that accessibility services should not automatically announce changes to this view.
Is the view important for accessibility?
The view is not important for accessibility, nor are any of its descendant views.
Is horizontal layout direction inherited from parent view?
Horizontal layout direction of this view is inherited from its parent.
What is an Adapter View?
An Adapter View can be used to display large sets of data efficiently in form of List or Grid etc, provided to it by an Adapter.
What is an adapter in a database?
Note: Adapter is only responsible for taking the data from a data source and converting it into View and then passing it to the AdapterView. Thus, it is used to manage the data. AdapterView is responsible for displaying the data. Therefore, you can take the data from a database or an ArrayList or any other data source and then, ...
How many items can an adapter view load?
Hence no matter how big your data set is, the Adapter View will always load only 5 or 6 or maybe 7 items at once, depending upon the display size . Hence saving memory.
What is grid view?
GridView is a ViewGroup that displays items in a two-dimensional, scrollable grid.
What is an adapter view?
An adapter view, as its name suggests, is a View object. This means, you can add it to your activities the same way you add any other user interface widget. However, it is incapable of displaying any data on its own. Its contents are always determined by another object, an adapter.
What is an adapter in a data set?
An adapter is responsible for retrieving data from the data set and for generating View objects based on that data . The generated View objects are then used to populate any adapter view that is bound to the adapter.
How to store viewholder object in convertview?
To store the view holder object in convertView, use its setTag () method. And now, every time getView () is called, you can retrieve the view holder object from convertView using the getTag () method and update the TextView widgets inside it using their setText () methods.
How often is the findViewByID method called?
In the previous step, you might have noticed that, even though we made sure that the layout of the list items is inflated only once, the findViewById () method, which consumes many CPU cycles, is called every time the getView () method is called.
What is the position parameter in getView?
Inside the getView () method, you must use the position parameter as an index of the array and fetch the item at that index.
Can you create an adapter class?
You can create your own adapter classes from scratch, but most developers choose to use or extend adapter classes provided by the Android SDK, such as ArrayAdapter and SimpleCursorAdapter. In this tutorial, we focus on the ArrayAdapter class.
Does array adapter work with strings?
Additionally, because the ArrayAdapter class can only work with strings, you need to make sure the layout of the generated View objects contains at least one TextView widget.
What is a view in a list?
The View refers to a specific item within the AdapterView. In a ListView it is the row. Thus, you can get a reference to a TextView within a row by saying something like this:
What is the position of a list view?
The position is the position of the view in the parent. For a ListView, it is the row number. The top row is position 0, the second row is position 1, the third row is position 2, etc. Note that if your ListView has a header view (like if you did ListView.addHeaderView (View)) then the header view would be position 0 and the actual rows would start their numbering at 1.
What does "datatype unknown" mean?
The ? means that the datatype is unknown and it can be any type.
What is adapter view?
An Adapter View displays the set of data in the form of List or Grid provided by the Adapter. It has the capability to display a large number of items on the User Interface efficiently. An Android Adapter is responsible for taking the data from the source and put it in the AdapterView. And it is the responsibility of AdapterView to display the data. Adaptors help us make the user interface interactive and friendly to use.
What is array adapter?
ArrayAdapter – ArrayAdapter presents the items in a single list backed by an array.
What are the different types of adapters?
Android provides us with following different types of Adapters that are used to fill the data in UI components: 1 BaseAdapter – BaseAdapter is the parent adapter for the rest of the Adapters. 2 CursorAdapter – This adapter makes it easy and more controlled to access the binding of data values. 3 ArrayAdapter – ArrayAdapter presents the items in a single list backed by an array. 4 Custom ArrayAdapter – It displays the custom list of an Array. 5 SimpleAdapter – SimpleAdapter is an easy adapter to map static data to the views through the XML file. 6 Custom SimpleAdapter – It displays a customized list and enables us to access the child data of the list or grid view.
What is ListView speciality?
The speciality of ListView is that it shows the items in a Horizontal form, here each item lies below the other. These items are displayed in Vertically- Scrollable collection. The example is given below:
When to use CursorAdapter?
We use CursorAdapter when we need to display some data using the SQLite database query. This Android Adapter enables us to use the resources easily in ListView.
What is getViewTypeCount?
getViewTypeCount () – This method returns the number of types of Views created using getView ().
What is grid view?
In a Grid View, each item is displayed in a tabular form or a 2-Dimensional view, that is in rows and columns. This is also a vertically-scrollable view. To understand this view, consider the following image:
check ()
This accepts view assertions and checks the passed in view assertions.
inAdapterView ()
This accepts view matchers. It selects the particular AdapterView based on the passed in view matchers and returns DataInteraction object to interact with the matched AdapterView
atPosition ()
This accepts an argument of type integer and refers the position of the item in the underlying data. It selects the view corresponding to the passed in positional value of the data and returns DataInteraction object to interact with the matched view. It will be useful, if we know the correct order of the underlying data.
onChildView ()
This accepts view matchers and matches the view inside the specific child view. For example, we can interact with specific items like Buy button in a product list based AdapterView.
What Is An Adapter?
How Do Adapter Views Work?
- Adapter views can display large data sets very efficiently. For instance, the ListView and GridViewwidgets can display millions of items without any noticeable lag while keeping memory and CPU usage very low. How do they do that? Different adapter views follow different strategies. However, here's what most of them usually do. 1. They render only those Viewobjects that are ei…
Creating An ArrayAdapter
- To create an adapter, you need the following: 1. a data set 2. a resource file containing the layout of the generated Viewobjects Additionally, because the ArrayAdapter class can only work with strings, you need to make sure the layout of the generated View objects contains at least one TextViewwidget.
Creating A List
- To display a vertically scrollable list of items, you can use the ListViewwidget. To add the widget to your activity, you can either drag and drop it inside the activity's layout XML file or create it using its constructor in your Java code. For now, let's do the latter. Usually, no other user interface widgets are placed inside a layout that contains a ListView. Therefore, pass the ListVie…
Creating A Grid
- To display a vertically scrollable two-dimensional grid of items, you can use the GridView widget. Both ListView and GridView are subclasses of the abstract AbsListViewclass and they share many similarities. Therefore, if you know how to use one, you know how to use the other as well. Use the constructor of the GridView class to create a new instance and pass it to the setContent…
Adding Event listeners
- It is possible to listen for click and long click events on the items inside an adapter view. As an example, let's add a click event listener to the GridView. Create a new instance of an anonymous class that implements the AdapterView.OnItemClickListener interface and pass it to the setOnItemClickListener() method of the GridView object. Android Studio automatically gener…
Extending The ArrayAdapter
- An ArrayAdapter can handle only one TextView widget inside the layout of the Viewobjects it generates. To broaden its capabilities you must extend it. Before we do that, however, let's create a slightly more complex data set. Instead of strings, let's say our data set contains objects of the following class: This is the data set we will be using: As you can see, the Cheese class contains …
Using A View Holder
- The getView()method is called repeatedly by the adapter view to populate itself. Therefore, you must try to minimize the number of operations you perform in it. In the previous step, you might have noticed that, even though we made sure that the layout of the list items is inflated only once, the findViewById() method, which consumes many CPU cycles, is called every time the getView(…
Conclusion
- In this tutorial, you learned how to create an adapter and use it to populate various adapter views. You also learned how to create your own custom adapter. Although we only focused on the ArrayAdapter, ListView, and GridViewclasses, you can use the same techniques for other adapters and adapter views the Android SDK offers. The Android Support Library includes the RecyclerVie…