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why can I not import JSON object in java 1.8
shivangi007 (0)

I am trying to import a library that can help me access JSONObjects, but nothing seems to work. Does anybody know which library needs to be imported (there is no org.json)

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shivangi007 (0)

this is . not what I was looking for

[deleted]

PLEASE MARK ME AS ANSWERED IF YOU FIND THIS HELPFUL.
How to parse JSON in Java
JSON (JavaScript Object Notation) is a lightweight, text-based, language-independent data exchange format that is easy for humans and machines to read and write. JSON can represent two structured types: objects and arrays. An object is an unordered collection of zero or more name/value pairs. An array is an ordered sequence of zero or more values. The values can be strings, numbers, booleans, null, and these two structured types.

Below is a simple example from Wikipedia that shows JSON representation of an object that describes a person. The object has string values for first name and last name, a number value for age, an object value representing the person’s address, and an array value of phone number objects.

{
"firstName": "John",
"lastName": "Smith",
"age": 25,
"address": {
"streetAddress": "21 2nd Street",
"city": "New York",
"state": "NY",
"postalCode": 10021
},
"phoneNumbers": [
{
"type": "home",
"number": "212 555-1234"
},
{
"type": "fax",
"number": "646 555-4567"
}
]
}
JSON Processing in Java : The Java API for JSON Processing JSON.simple is a simple Java library that allow parse, generate, transform, and query JSON.

Getting Started : You need to download the json-simple-1.1 jar and put it in your CLASSPATH before compiling and running the below example codes. For importing jar in IDE like eclipse, refer here.

Json-Simple API : It provides object models for JSON object and array structures. These JSON structures are represented as object models using types JSONObject and JSONArray. JSONObject provides a Map view to access the unordered collection of zero or more name/value pairs from the model. Similarly, JSONArray provides a List view to access the ordered sequence of zero or more values from the model.

Write JSON to a file

Let us see an example that writes above JSON data into a file “JSONExample.json”, with help of JSONObject and JSONArray.

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// Java program for write JSON to a file

import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.LinkedHashMap;
import java.util.Map;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;

public class JSONWriteExample
{
public static void main(String[] args) throws FileNotFoundException
{
// creating JSONObject
JSONObject jo = new JSONObject();

    // putting data to JSONObject 
    jo.put("firstName", "John"); 
    jo.put("lastName", "Smith"); 
    jo.put("age", 25); 
      
    // for address data, first create LinkedHashMap 
    Map m = new LinkedHashMap(4); 
    m.put("streetAddress", "21 2nd Street"); 
    m.put("city", "New York"); 
    m.put("state", "NY"); 
    m.put("postalCode", 10021); 
      
    // putting address to JSONObject 
    jo.put("address", m); 
      
    // for phone numbers, first create JSONArray  
    JSONArray ja = new JSONArray(); 
      
    m = new LinkedHashMap(2); 
    m.put("type", "home"); 
    m.put("number", "212 555-1234"); 
      
    // adding map to list 
    ja.add(m); 
      
    m = new LinkedHashMap(2); 
    m.put("type", "fax"); 
    m.put("number", "212 555-1234"); 
      
    // adding map to list 
    ja.add(m); 
      
    // putting phoneNumbers to JSONObject 
    jo.put("phoneNumbers", ja); 
      
    // writing JSON to file:"JSONExample.json" in cwd 
    PrintWriter pw = new PrintWriter("JSONExample.json"); 
    pw.write(jo.toJSONString()); 
      
    pw.flush(); 
    pw.close(); 
} 

}
Output from file “JSONExample.json” :

{
"lastName":"Smith",
"address":{
"streetAddress":"21 2nd Street",
"city":"New York",
"state":"NY",
"postalCode":10021
},
"age":25,
"phoneNumbers":[
{
"type":"home", "number":"212 555-1234"
},
{
"type":"fax", "number":"212 555-1234"
}
],
"firstName":"John"
}
Note : In JSON, An object is an unordered set of name/value pairs, so JSONObject doesn’t preserve the order of an object’s name/value pairs, since it is (by definition) not significant. Hence in our output file, order is not preserved.

Read JSON from a file

Let us see an example that read JSON data from above created file “JSONExample.json” with help of JSONParser, JSONObject and JSONArray.

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// Java program to read JSON from a file

import java.io.FileReader;
import java.util.Iterator;
import java.util.Map;

import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.*;

public class JSONReadExample
{
public static void main(String[] args) throws Exception
{
// parsing file "JSONExample.json"
Object obj = new JSONParser().parse(new FileReader("JSONExample.json"));

    // typecasting obj to JSONObject 
    JSONObject jo = (JSONObject) obj; 
      
    // getting firstName and lastName 
    String firstName = (String) jo.get("firstName"); 
    String lastName = (String) jo.get("lastName"); 
      
    System.out.println(firstName); 
    System.out.println(lastName); 
      
    // getting age 
    long age = (long) jo.get("age"); 
    System.out.println(age); 
      
    // getting address 
    Map address = ((Map)jo.get("address")); 
      
    // iterating address Map 
    Iterator<Map.Entry> itr1 = address.entrySet().iterator(); 
    while (itr1.hasNext()) { 
        Map.Entry pair = itr1.next(); 
        System.out.println(pair.getKey() + " : " + pair.getValue()); 
    } 
      
    // getting phoneNumbers 
    JSONArray ja = (JSONArray) jo.get("phoneNumbers"); 
      
    // iterating phoneNumbers 
    Iterator itr2 = ja.iterator(); 
      
    while (itr2.hasNext())  
    { 
        itr1 = ((Map) itr2.next()).entrySet().iterator(); 
        while (itr1.hasNext()) { 
            Map.Entry pair = itr1.next(); 
            System.out.println(pair.getKey() + " : " + pair.getValue()); 
        } 
    } 
} 

}
Output:

John
Smith
25
streetAddress : 21 2nd Street
postalCode : 10021
state : NY
city : New York
number : 212 555-1234
type : home
number : 212 555-1234
type : fax
This article is contributed by Gaurav Miglani. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to [email protected] See your article appearing on the GeeksforGeeks main page and help other Geeks.

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