Reading and Writing JSON in Kotlin with Jackson

In this article we’ll be taking a look at how to read and write JSON files in Kotlin, specifically, using the Jackson library.

Jackson Dependency

To utilize Jackson, we’ll want to add its jackson-module-kotlin dependency to our project. If you’re using Maven, you can simply add:

<dependency>
    <groupId>com.fasterxml.jackson.module</groupId>
    <artifactId>jackson-module-kotlin</artifactId>
    <version>2.12.1</version>
</dependency>

Or, if you’re using Gradle, you can add:

implementation 'com.fasterxml.jackson.module:jackson-module-kotlin:2.12.1'

With the dependency in place, let’s define a JSON object we’ll want to read:

{
   "id":101,
   "username":"admin",
   "password":"Admin123",
   "fullName":"Best Admin"
}

Reading a JSON Object to Kotlin Object

Let’s take a look at how we can deserialize a JSON object into a Kotlin object. Since we’ll want to convert the JSON contents into a Kotlin object, let’s define a User data class:

data class User (
    val id: Int,
    val username: String,
    val password: String,
    val fullName: String
)

Then, we’ll want to instantiate the object mapper, which can easily be done with:

import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper

// Registering the Kotlin module with the ObjectMpper instance
val mapper = jacksonObjectMapper()

// JSON String
val jsonString = """{
    "id":101,
    "username":"admin",
    "password":"Admin123",
    "fullName":"Best Admin"
    }"""

With that done, we can pass JSON contents into our ObjectMapper methods, such as readValue(), as usual for Jackson:

// Read data from a JSON string
val userFromJson = mapper.readValue<User>(jsonString)
// Or
val userFromJsonWithType: User = mapper.readValue(jsonString)

If we print the value of userFromJson we’ll see something like this:

User(id=101, username=admin, password=Admin123, fullName=Best Admin)

The readValue() function can be used with or without the Class parameter, as you saw a little earlier with the two variables (userFromJson and userFromJsonWithType).

Note: Using the function without the Class parameter will materialize the type and automatically create a TypeReference for Jackson.

#kotlin

What is JSON? | JSON Objects and JSON Arrays | Working with JSONs Tutorial

In this video, we work with JSONs, which are a common data format for most web services (i.e. APIs). Thank you for watching and happy coding!

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What is an API?
https://youtu.be/T74OdSCBJfw

JSON Google Extension
https://chrome.google.com/webstore/detail/json-formatter/bcjindcccaagfpapjjmafapmmgkkhgoa?hl=en

Endpoint Example
http://maps.googleapis.com/maps/api/geocode/json?address=13+East+60th+Street+New+York,+NY

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#jsons #json arrays #json objects #what is json #jsons tutorial #blondiebytes

Juned Ghanchi

1621508255

Kotlin App Development Company in India, Hire Kotlin Developers

We are a prime Kotlin app developer in India. We build and provide the best personalized Android apps, migration services, ongoing maintenance, and management.

We have the most efficient Kotlin developers that build ultramodern, interactive, and secure mobile apps. The technologies we use to create the most advanced Kotlin apps are AR/VR, AI/ML, IoT, etc.

Hire Kotlin app developers in India. Meet us, and we will help you meet all of your technology requirements.

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https://loizenai.com Programming Tutorial

1618249936

Kotlin - Convert Object to/from JSON with Jackson 2.x » grokonez

https://grokonez.com/kotlin/kotlin-convert-object-tofrom-json-jackson-2-x

Kotlin – Convert Object to/from JSON with Jackson 2.x

This tutorial shows you how to use Jackson 2.x to convert Kotlin object to/from JSON.

I. Technology

- Java 1.8 - Kotlin 1.1.2 - Maven 3.5.1

II. Overview

1. Goal

Convert JSON string/JSON file/JSON url to Person(name:String,age:Int,messages:List) Kotlin Object, then convert Person object to JSON string/JSON file.

2. Steps to do

- add Dependency:

<dependency>
	<groupId>org.jetbrains.kotlin</groupId>
	<artifactId>kotlin-stdlib</artifactId>
	<version>1.1.2</version>
</dependency>
<dependency>

<groupId>com.fasterxml.jackson.module</groupId>

<artifactId>jackson-module-kotlin</artifactId>

<version>2.8.8</version>

</dependency>

import com.fasterxml.jackson.module.kotlin.*
use ObjectMapper instance:

More at:

https://grokonez.com/kotlin/kotlin-convert-object-tofrom-json-jackson-2-x

#kotlin #json #jackson

Autumn Blick

1593251880

JSON Parsing in Android - Step by Step Implementation

JSON Structures in Android

JSON uses two types of brackets that are as follows:

[] – To declare the elements of Array in JSON, they’re written in square brackets.
{} – To create JSON objects, the elements are written in curly brackets.

JSON has the following types of structures that are:

1. JSON Objects

The elements inside the curly brackets are known as Objects.

2. JSON Array

A list of values, known as Arrays.

3. JSON Key-Value

This data is stored as a pair of keys and values. Here the keys can be a name, a number for which the values can be Seema, 98767586 etc.

Why JSON Parsing in Android over XML?

Let us see some reasons for why to choose JSON over XML:

It is much easier and quicker with high performance
It can use arrays
Its libraries do not depend on other libraries
The codes written in JSON are short, clean and easy to understand
It is free to open use and open-source tool
In JSON value retrieval is easy
It has a fully automated way of serializing/deserializing JavaScript.
It is supported by many Ajax toolkits and most of the backend technologies.

Examples of XML and JSON

Let us see the code difference of JSON and XML files:

XML Example:

<?xml version= “1.0” encoding= “” ?>
<student>
        <student>
  <name> Sia Sharma</name>
  <city> Chandigarh</city>
         </student>
        <student>
  <name>Dimple D’souza</name>
  <city> Nagpur</city>
         </student>
      <student>
  <name>Anna Jones</name>
  <city> Mumbai</city>
         </student>
  </student>

JSON Example:

{ “students”: [
{ “name”: “Sia Sharma”, “city”: “Chandigarh”},
{ “name”: “Prachi D’Souza”, “city”: “Nagpur”},
{ “name”: “Annas Jones”, “city”: “Mumbai”}
]}

I hope the difference is all clear in front of you. This is how simple JSON is and how easily it could be understood.

#android tutorials #json parsing in android #json parsing in android example #json parsing in android step by step #json parsing with android #read json file android

Kennith Blick

1625768100

Reading and Writing to Files in Python - Intermediate Python Tutorial #2

In this Python tutorial, we will learn how to deal with text files in Python using the built-in open function. You will understand how to use the most important modes: read, write and append.
That’s not all! We will discuss about file parsing and touch important string methods used for that such as: strip( ) and split( ). Finally we wrap up with a parsing file exercise to practice the new concepts. After that video you will be confident to deal with text files which is a very important skill to have as a programmer.

Playlist: Intermediate Python Tutorials | Video #2
Access the codes here: https://github.com/rscorrea1/youtube.git

Timestamp:
00:00 - Summary of the video
00:17 - Types of files
00:43 - How to open a file
01:17 - File modes
02:15 - How to read data from a file
03:00 - with statement
04:10 - readlines( ) method
05:05 - String: strip( ) method
06:22 - How to iterate over a file line by lin
08:47 - How to write data to a file
11:43 - How to append data to a file
12:37 - Exercise: Parsing a text file
16:14 - Converting data types
17:00 - Next video announcement

Thumbnail:
Photo by Mario Ho on Unsplash

#reading #writing #python #intermediate python tutorial #reading and writing to files in python