ContentProvider Android based interview questions and answers
1) Describe content providers
A ContentProvider provides data from one application to another, when requested. It manages access to a structured set of data. It provides mechanisms for defining data security. ContentProvider is the standard interface that connects data in one process with code running in another process.
When you want to access data in a ContentProvider, you must instead use the ContentResolver object in your application’s Context to communicate with the provider as a client. The provider object receives data requests from clients, performs the requested action, and returns the results.
2) Access data using Content Provider:
Start by making sure your Android application has the necessary read access permissions. Then, get access to the ContentResolver object by calling getContentResolver() on the Context object, and retrieving the data by constructing a query using ContentResolver.query().
The ContentResolver.query() method returns a Cursor, so you can retrieve data from each column using Cursor methods.
3) How would you access data in a ContentProvider?
In Android when we want to share data between two applications we are using Content Provider. It has a complete mechanism to share data between applications. It will also provide security while sharing data from one application to another application. For getting data from any Content Provider you need to create Content Resolver. For Creating Content Resolver, you need to call Activity’s getContentResolver method.
For Modifying data from Content Provider, you can invoke the basic method of Content Resolver like insert, delete, update and query. These operations are the same as the SQLite DB Operation.
Android we have two steps for retrieving data from a Content Provider:
- Write-read permission for reading data from Content Provider
- Write a query to send a request to the content provider.
For sharing data from one application to another application we are using Content Provider in android. Other application can access data from Content Provider using the provider client object. These provider client object providing an interface between application to access data and handle inter-process communication. Content Provider is saving data in the form of Tables. These tables are having the same schema as relational database tables.
To access the data from the content provider, we use the ContentResolver client object. ContentResolver provides basic methods related to database storage. ContentResolver object and Content Provider objects are handling interprocess communication between application. The ContentResolver methods provide the basic create, retrieve, update, and delete functions of persistent storage.
To retrieve data from a content provider, we need to follow these steps:
- Send Request the read access permission for the provider.
- Write the code that sends a query to the provider
In Android, applications cannot access the data of other application. For sharing data between two applications, we need to provide permissions. Here we have to provide permission on both side:
- The content provider must allow other apps to access its data.
- The user must allow the client app to access the content provider.
There are many scenarios where we want other application can read our application data but can not change it. Or sometimes we are providing them access to modify our application data.
In your scenario, we can provide read permission “android:readPermission” attribute in the provider so that Google calendar read data from Gmail application.
android:readPermission="com.android.GMAIL.calenderwithcontentpfonrovider.PERMISSION"
How to set permission for content provider?
Read permission can be set in android:readPermission
Write permission can be set in android:writePermission
URI level permission can be set using path-permission tag
Use android:grantUriPermissions to grant temporary permission
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