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Learn how to encode JSON array data using the JSONArray class. Also learn how to write an encoded JSON string to an output text file for transport to a different computing environment.

Revised: Thu Jun 02 19:27:08 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 encode JSON array data using the JSONArray class. It also shows how to write an encoded JSON string to an output text file for transport to a different programmingenvironment.

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

  • Figure 1 . Prettified version of output file contents.
  • Figure 2 . Beginning of output file contents.
  • Figure 3 . Decoded output data.

Listings

  • Listing 1 . Beginning of the class and the main method.
  • Listing 2 . Instantiate and populate a JSONArray object.
  • Listing 3 . Populate hashMapA.
  • Listing 4 . Create and populate another similar JSON object.
  • Listing 5 . Put the players in the game.
  • Listing 6 . Write the JSON string to an output file.
  • Listing 7 . The program named Code.java.

General background information

As you learned in the page titled Json0210: Structure of the json-simple Java Library , the JSONArray class extends the standard Java ArrayList class. Once you have an object of the JSONArray class, you have access to all of the methods defined in and inherited into the JSONArray class.

The sample program that follows will use the JSONArray class to construct a JSON string containing nested arrays and will then write thestring to an output file suitable for transport to a different programming environment.

A later page in this book will read the JSON string from the file and decode it into its component parts.

Discussion and sample code

The program named Code (see Listing 7 ) creates a JSON string and writes it to an output file. The json string contains an array, which in turn contains two nested arrays.

Beginning of the class and the main method

I will discuss and explain the program in fragments. The first fragment is shown in Listing 1 .

Listing 1 . Beginning of the class and the main method. import org.json.simple.JSONObject; import org.json.simple.JSONArray;import java.io.PrintWriter; import java.io.File;import java.io.IOException; class Code{public static void main(String[] args){//Create a json object. which is a subclass // of the Java HashMap class.JSONObject hashMapA = new JSONObject();//Populate the json object with a key/value // pair.hashMapA.put("name","Tom");

Questions & Answers

Ayele, K., 2003. Introductory Economics, 3rd ed., Addis Ababa.
Widad Reply
can you send the book attached ?
Ariel
?
Ariel
What is economics
Widad Reply
the study of how humans make choices under conditions of scarcity
AI-Robot
U(x,y) = (x×y)1/2 find mu of x for y
Desalegn Reply
U(x,y) = (x×y)1/2 find mu of x for y
Desalegn
what is ecnomics
Jan Reply
this is the study of how the society manages it's scarce resources
Belonwu
what is macroeconomic
John Reply
macroeconomic is the branch of economics which studies actions, scale, activities and behaviour of the aggregate economy as a whole.
husaini
etc
husaini
difference between firm and industry
husaini Reply
what's the difference between a firm and an industry
Abdul
firm is the unit which transform inputs to output where as industry contain combination of firms with similar production 😅😅
Abdulraufu
Suppose the demand function that a firm faces shifted from Qd  120 3P to Qd  90  3P and the supply function has shifted from QS  20  2P to QS 10  2P . a) Find the effect of this change on price and quantity. b) Which of the changes in demand and supply is higher?
Toofiq Reply
explain standard reason why economic is a science
innocent Reply
factors influencing supply
Petrus Reply
what is economic.
Milan Reply
scares means__________________ends resources. unlimited
Jan
economics is a science that studies human behaviour as a relationship b/w ends and scares means which have alternative uses
Jan
calculate the profit maximizing for demand and supply
Zarshad Reply
Why qualify 28 supplies
Milan
what are explicit costs
Nomsa Reply
out-of-pocket costs for a firm, for example, payments for wages and salaries, rent, or materials
AI-Robot
concepts of supply in microeconomics
David Reply
economic overview notes
Amahle Reply
identify a demand and a supply curve
Salome Reply
i don't know
Parul
there's a difference
Aryan
Demand curve shows that how supply and others conditions affect on demand of a particular thing and what percent demand increase whith increase of supply of goods
Israr
Hi Sir please how do u calculate Cross elastic demand and income elastic demand?
Abari
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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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