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. Here Simple Adapter is one type of Adapter. It is basically an easy adapter to map static data to views defined in our XML file(UI component) and is used for customization of List or Grid items. Here we use an ArrayList of Map (e.g. hashmap, mutable map, etc.) for data-backing. Each entry in an ArrayList is corresponding to one row of a list. The Map contains the data for each row. Now to display the row we need a view for which we used to specify a custom list item file (an XML file).
General Syntax of SimpleAdapter
SimpleAdapter(Context context, List<? extends Map<String, ?>> data, int resource, String from, int to)
***Here context, data, resource, from, and to are five parameters***
|context||Context||When we make an object of SimpleAdapter class It is used to pass the context ( The reference of current activity).|
List<? extends Map<String, ?>>
*** it means a List of Maps whose key‘s type is String and Value can be any datatype.
|Each element of the List is different Maps that contain the data of each row and should include all the entries specified in the “from” string array. In our project, we shall use ArrayList.|
|This parameter is used to pass the resource id of the layout ( XML file ) which should contain the different views of each row of the list. The layout file should include at least those named views defined in “to”.|
|from||An array of String type||A list of column names that will be added to the Map associated with each item. In this array, there should be a column name for each item (Views) of each row of the list.|
|to||An array of int type.||This array parameter stores the ids of different views that should display the column in the “from” parameter. These should all be TextViews. The first N views in this list are given the values of the first N columns in the “from” parameter.|
A sample image is given below to get an idea about what we are going to do in this article. In this project, we are going to make this application which has a list of some fruits and in each row of the list has a fruit image and name. Note that we are going to implement this same project in both Kotlin and Java languages. Now you choose your preferred language.
Step by Step Implementation
Step 1: Create a New Project
Open Android Studio > Create New Project > Select an Empty Activity > Give a project name (Here our project name is “GFG_SimpleAdapter“).
*** Here you can choose either Kotlin or Java which you preferred and chose the API level according to your choice.
***After creating the project successfully, please paste some pictures into the drawable folder in the res directory. Now you can use the same pictures which I have used in my project otherwise you can choose pictures of your own choice. To download the same pictures please click on the below-given link:
***please note that it is optional***
Step 2: Working with the activity_main.xml file
Step 3: Create another XML file (named list_row_items) and create UI for each row of the ListView
Create a new Layout Resource file and name it as list_row_items.
Below is the code for the list_row_items.xml file.
Step 4: Working with the MainActivity file
Here we will show you how to implement SimpleAdapter both in Java and Kotlin. Now you choose your preferred one. Below is the code for the MainActivity file. Comments are added inside the code to understand the code in more detail.
Thus SimpleAdapter holds data and sends the data to the adapter view then the view can take the data from the adapter view and shows the data on the ListView which we have created earlier.
***Please note you have to choose any one language between Java and Kotlin as MainActivity for a particular project***
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