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Learn how to use the JSONObject class to encode key/value pairs into JSON strings.

Revised: Thu Jun 02 19:24:40 CDT 2016

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Table of contents

Preface

This is a page from the book titled The json-simple Java Library . The book explains how to use the json-simple Java library to generate, transform, and query JSON text. This page explains how to use the JSONObject class to encode key/value pairs into JSON strings.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the Figuresand Listings while you are reading about them.

Figures

Listings

  • Listing 1 . Create ArrayList containers.
  • Listing 2 . Create and populate a JSONObject object.
  • Listing 3 . Create and populate two more JSONObject objects.
  • Listing 4 . Encode the data into JSON strings.
  • Listing 5 . Display the JSON strings.
  • Listing 6 . The program named Code.java.

General background information

As you learned in the earlier page titled Json0210: Structure of the json-simple Java Library , the class named JSONObject extends the standard Java class named HashMap . Therefore, once you have an object of the class named JSONObject , you can call any of the methods defined in or inherited into the JSONObject class on that object.

In the sample program that follows, we will use the put method that is inherited from the HashMap class to populate the object with key/value pairs. We will use the toJSONString method that is defined in the JSONObject class to transform the populated object into a JSON string.

Discussion and sample code

The program named Code (see Listing 6 ) constructs three JSONObject objects, populates the objects with key/value pairs, and saves the JSONObject objects in an ArrayList object. (Actually it saves references to the JSONObject objects in the ArrayList object.)

Then it transforms each JSONObject object into a JSON string. At this point, the JSON strings could be written to an outputstream and transferred to a different programming environment. However, to keep the program simple, the program simply saves the JSON strings in a second ArrayList object for later display.

Then the program displays the JSON strings for comparison with the code that populated the JSONObject objects in the first place.

Create ArrayList containers

A complete listing of the program named Code is provided in Listing 6 near the end of the page. I will discuss and explain the code in fragments.The first fragment is shown in Listing 1 .

Listing 1 . Create ArrayList containers. import org.json.simple.JSONObject; import java.util.ArrayList;import java.util.Iterator; class Code {public static void main(String[] args){//Create a container for several JSON objects. ArrayList<JSONObject>listA = new ArrayList<JSONObject>(); //Create a container for several JSON stringsArrayList<String>listB = new ArrayList<String>();

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
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