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-write permission can be set in the attribute android:permission of provider tag
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

Aaaaaa

Comments

Post a Comment

Popular posts from this blog

Jetpack Compose based Android interview and questions

What’s Jetpack Compose and its Benefits? Jetpack Compose is a modern UI toolkit recently launched by Google which is used for building native Android UI. It simplifies and accelerates the UI development with less code, Kotlin APIs, and powerful tools.  Declarative Compatible Increase development speed Concise and Idiomatic Kotlin Easy to maintain Written in Kotlin To read more, refer  to  the article:  Jetpack Compose in Android Aaaaaa
Read more

Null safety based Kotlin interview questions and answers

Image
Nullable Non Nullable Types What’s Null Safety and Nullable Types in Kotlin? What is the Elvis Operator? Kotlin puts a lot of weight behind null safety which is an approach to prevent the dreaded Null Pointer Exceptions by using nullable types which are like  String? ,  Int? ,  Float?  etc. These act as a wrapper type and can hold null values. A nullable value cannot be added to another nullable or basic type of value. To retrieve the basic types we need to use safe calls that unwrap the Nullable Types. If on unwrapping, the value is null we can choose to ignore or use a default value instead. The Elvis Operator is used to safely unwrap the value from the Nullable. It’s represented as  ?:  over the nullable type. The value on the right hand side would be used if the nullable type holds a null. var str: String ? = "JournalDev.com" var newStr = str?: "Default Value" str = null newStr = str?: "Default Value" How is  !! different from ?. in unwrapping t
Read more

CustomView based Android interview questions and answers

1) Design one custom view for displaying TextView in UI with a attributes tribute like Title and Colour. When we need to create any custom view in Android, we will extend our class from the View parent class. In this scenario, as we need to create a custom Text view so we will create a subclass of TextView class.  And then we can our Custom textview in a layout.xml file. For example please follow below code where I am trying to create Custom TextView CustomTextView extends TextView { private String title;     private boolean color; title = tarry.getString(R.styleable.CustomTextView_settitle);             if(title == null)             setText("Custom Message");             else                 setText("Welcome to the Class"); color = tarry.getBoolean(R.styleable. CustomTextView _setColor, false);             if(color == true)             setTextColor(Color.RED); } We need to define our custom textview  in \res\layout  folder and write the code like as shown below. &l
Read more