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How to Read JSON Object From File in Java – Crunchify Tutorial

Last updated on  by  28 Comments

How to Read JSON Object From File in Java

In this Java Example I’ll use the same file which we have generated in previous tutorial.

Maven Dependency:

Previous Tutorial: https://crunchify.com/how-to-write-json-object-to-file-in-java/

Sample JSON file content:

CrunchifyJSONReadFromFile.java

Other must read: Create and Deploy simple Web Service and Web Service Client in Eclipse

Output:

Download json-simple-1.1.1.jar

Would love to know what you think. Chime in and share it as a comment. Don’t forget to share this guide!
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  5. Java: How to Parse JSONObject and JSONArrays – Beginner’s Guide
  6. How to write JSON object to File in Java?
  • AntiStupidity

    We get raw files like this in .json or .txt format. how can i change it into java object and then insert every field in the database?

    {“Header”:{“BeneficiaryId”:”123″,”BeneficiaryZip”:”28006″,”IcdVersionIndicator”:”0″,”PrimaryCarePhysicianYnFlag”:”Y”},”Lines”:[{“LineNumber”:1,”DateOfService”:”1/30/2016″,”Hcpcs”:”A123″,”Modifier01″:”BA”,”Modifier02″:”RR”,”Units”:”1.0″,”PlaceOfService”:”01″,”Charges”:”500″,”RenderingNpi”:”1000000000″,”RenderingTaxonomy”:”335E11111X”}]}

  • Omoba A

    Thanks for the tutorial, it was a great help. Please can you advise how to approach multiple objects within a single json file? My list is:

    {
    “dummy1” : “5943”,
    “dummy2” : “1222”,
    “dummy3” : “1321”,

    }

    {
    “dummy1” : “5493”,
    “dummy2” : “0112”,
    “dummy3” : “1141”,
    }

    My code works with only one object. However when I have multiple objects like described above, it gives me an error ” Unexpected token LEFT BRACE({) at position 785.” I think it is because of the second brace that starts the second object. I would appreciate your advice. Thanks!

    • Hi Omoba A – above json object is not right. Try providing below JSONArray Object.

      [{
		"dummy1": "5943",
		"dummy2": "1222",
		"dummy3": "1321"
	},
	{
		"dummy1": "5493",
		"dummy2": "0112",
		"dummy3": "1141"
	}
]
  • Omoba A

    Thank you so much, it was a GREAT help 🙂

    Please can you give directions for multiple objects within a single json file? I get an error saying “unexpected token LEFT BRACE at position 785”.

  • Allamaprabhu G

    can we get sample example where the method or the piece of code which can read any json file.
    even the complex json file. this my json file, I need to read the key and value
    my key are : system, value, code,display,description sys_id,sys_name,sys_ver(apart from system and value, other will repeat in other child for bodysite, status.). How do I read this json.
    it should be common code which can read all other json file
    {
    “items”: [
    {
    “identifier”: {
    “system”: “CDM”,
    “value”: “$ROW_WID$”
    },
    “code”: {
    “coding”: [{
    “code”: “$DIAGNOSIS_CODE$”,
    “display”: “$DIAGNOSIS_NAME$”,
    “description”:”$DIAGNOSIS_DESC$”,
    “sys_id”:”$DIAGNOSIS_CD_SYS_ID$”,
    “sys_name”: “$DIAGNOSIS_CD_SYS_NAME$”,
    “sys_ver”: “$DIAGNOSIS_CD_SYS_VER$”
    }]
    }

    ,
    “bodySite”: {
    “coding”: [{
    “code”: “$DIAGNOSIS_STATUS_CODE$”,
    “display”: “$DIAGNOSIS_STATUS_NAME$”,
    “description”:”$DIAGNOSIS_STATUS_DESC$”,
    “sys_id”:”$DIAGNOSIS_STATUS_CD_SYS_ID$”,
    “sys_name”: “$DIAGNOSIS_STATUS_CD_SYS_NAME$”,
    “sys_ver”: “$DIAGNOSIS_STATUS_CD_SYS_VER$”
    }]
    },
    “status”: {
    “coding”: [{
    “code”: “$ANATOMICAL_SITE_CODE$”,
    “display”: “$ANATOMICAL_SITE_NAME$”,
    “description”:”$ANATOMICAL_SITE_DESC$”,
    “sys_id”:”$ANATOMICAL_SITE_CD_SYS_ID$”,
    “sys_name”: “$ANATOMICAL_SITE_CD_SYS_NAME$”,
    “sys_ver”: “$ANATOMICAL_SITE_CD_SYS_VER$”
    }]
    },
    “onsetDate”:”$AGE_AT_FIRST_ONSET$”,
    “onsetAge”: “$DIAGNOSIS_ONSET_DT$”,
    “reportedDate” : {
    “start” : “$DIAGNOSIS_REPORTED_DT$”,
    “end” : “$DIAGNOSIS_END_DT$”
    } ,
    “Encounter”: {
    “identifier”: {
    “system”: “CDM”,
    “value”: “$ENCOUNTER_NUMBER$”
    } ,
    “type”: {
    “coding”:[{
    “code”: “$ENCOUNTER_TYPE_CODE$”,
    “display”: “$ENCOUNTER_TYPE_NAME$”,
    “description”:”$ENCOUNTER_TYPE_DESC$”,
    “sys_id”: “$ENCOUNTER_TYPE_CD_SYS_ID$”,
    “sys_name”: “$ENCOUNTER_TYPE_CD_SYS_NAME$”,
    “sys_version”: “$ENCOUNTER_TYPE_CD_SYS_VER$”
    }]
    } ,
    “Location”: {
    “identifier”: {
    “system”: “$CDM$”,
    “value”: “$FACILITY_NUMBER$”
    },
    “name”:”$FACILITY_NAME$”,
    “type”: {
    “coding”:[{
    “code”: “$FACILITY_TYPE_CODE$”,
    “display”: “$FACILITY_TYPE_NAME$”,
    “description”:”$FACILITY_TYPE_DESC$”,
    “sys_id”: “$FACILITY_TYPE_CD_SYS_ID$”,
    “sys_name”: “$FACILITY_TYPE_CD_SYS_NAME$”,
    “sys_version”: “$FACILITY_TYPE_CD_SYS_VER$”
    }]

    }

    },
    “sequence” : “$ENCOUNTER_SEQUENCE_NUMBER$”
    },

    “Practitioner”: {
    “identifier”: {
    “system”: “$CDM$”,
    “value”: “$SVCPRV_IDENTIFIER$”
    } ,
    “type”: {
    “coding”:[{
    “code”: “$SVCPRV_TYPE_CODE$”,
    “display”: “$SVCPRV_TYPE_NAME$”,
    “description”:”$SVCPRV_TYPE_DESC$”,
    “sys_id”: “$SVCPRV_TYPE_CD_SYS_ID$”,
    “sys_name”: “$SVCPRV_TYPE_CD_SYS_NAME$”,
    “sys_version”: “$SVCPRV_TYPE_CD_SYS_VER$”
    }]
    },
    “specialty” :{
    “coding”: [{
    “code”: “$SPECIALTY_CODE$”,
    “display”: “$SPECIALTY_NAME$”,
    “description”:”$SPECIALTY_DESC$”,
    “sys_id”:”$SPECIALTY_CD_SYS_ID$”,
    “sys_name”: “$SPECIALTY_CD_SYS_NAME$”,
    “sys_ver”: “$SPECIALTY_CD_SYS_VER$”
    }]
    }
    },

    “patient”:{
    “reference” :”$patient$”
    } ,
    “subject”:{
    “reference” :”$subject$”
    }
    }
    ]
    }

    • Hi @allamaprabhug:disqus that’s absolutely possible. Logic would be to iterate through all JSONObjects and get all Keys in loop.

      Assuming your JSON object is saved in a file “crunchify.json”, you can iterate over the attribute-value pairs as follows:

      JSONParser parser = new JSONParser();
Object obj = parser.parse(new FileReader("crunchify.json"));
JSONObject jsonObject = (JSONObject) obj;
for(Iterator iterator = jsonObject.keySet().iterator(); iterator.hasNext();) {
    String key = (String) iterator.next();
    System.out.println(jsonObject.get(key));
}
  • Siyabonga Cya Nzulwana

    Hi, and thank you for the example it helped. how does one read multiple objects without an array?
    like this below:

    {
    “details”: {
    “location”: “Cape Town”,
    “lastModified”: “2016-05-17”
    },
    “day1”: {
    “high”: 30,
    “low”: 13,
    “condition”: “Clear”
    },
    “day2”: {
    “high”: 19,
    “low”: 12,
    “condition”: “Partly Cloudy”
    },
    “day3”: {
    “high”: 17,
    “low”: 8,
    “condition”: “Partly Cloudy”
    },
    “day4”: {
    “high”: 19,
    “low”: 11,
    “condition”: “Clear”
    },
    “day5”: {
    “high”: 21,
    “low”: 11,
    “condition”: “Partly Cloudy”
    }
    }

    I am also expected to do the following:

    Read from the JSON file and display on a Webpage the following:

    a. Display each day’s High and Low temperatures.
    b. Out of all the min/max temperature values in the data set, display the average High Temperature, and the average Low Temperature for the 5 days. This needs to be calculated and not hard coded.
    c. Dynamically Display an image corresponding to each of the conditions in the above example. E.g. Sun for Clear, Cloud for Partly Cloudy…..
    d. Graph the High and Low Temperatures for the week on a graph.

    • Hi @siyabongacyanzulwana:disqus – I would say – it’s mandatory to have an array of JSONObjects to have it parse. Otherwise JSON parser will throw an error.

      Regarding all your 4 questions, I need more information about project. Could you please file request on Contact page here: https://crunchify.com/premium/

  • tjnapster555

    how to read json with more than one data like this

    [{
   "Name": "crunchify.com",
    "Author": "App Shah",
}
,{
"Name": "dsad.com",
"Author": "dasd Shah",
}]
  • Suhri Nadarin

    Hello, how would we parse them to the objects – with name, author, company variables – if we had a json input like:

    {
    “Company List”: [
    { “Name”: “crunchify.com”, “Author”: “App Shah”, “Compnay: Paypal” } ,
    { “Name”: “json richards”, “Author”: “App L”, “Compnay: Geegle” }
    ]
    }

    • Hi Suhri – Please put above JSON to file json.txt.

      Here is a complete example. I hope this helps:

      package crunchify.com.tutorials;
import java.io.FileReader;
import java.util.Iterator;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
/**
 * @author Crunchify.com
 * 
 */
public class CrunchifyJSONReadFromFile {
	public static void main(String[] args) {
		JSONParser parser = new JSONParser();
		try {
			Object obj = parser.parse(new FileReader("/Users/appshah/Documents/json.txt"));
			JSONObject jsonObject = (JSONObject) obj;
			JSONArray companyList = (JSONArray) jsonObject.get("Company List");
			Iterator iterator = companyList.iterator();
			while (iterator.hasNext()) {
				System.out.println(iterator.next());
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

      This will print out both JSONObjects for you.

  • ojus kulkarni

    Here I am having one problem, if I have array of objects, then how can I read those JSON objects from array ?

    • Hi Ojus – if you could share your JSON object and requirement, I might be able to help 🙂

    • Alisa

      Hi Ojus,
      I also had a similar problem, it turns out to be like this:

      Object obj = parser.parse(new FileReader(COLLECTION_FILE_NAME));
      JSONArray mainArray = (JSONArray) obj;

      • Omoba A

        I get the error, “Unexpected token LEFT BRACE(}) at position 785”

  • Nidhi Vora

    what if i have many objects in one json file and i need to parse it ?

    • Hi Nidhi – you have do change logic as per your need. If you have your json object handy, could you share? I might be able to quickly provide solution 🙂

  • Adrian Herrera Montenegro

    Im trying to read my own test.json file but I got an error on the line.

    JSONObject jsonObject = (JSONObject) obj;

    • Hi Adrian – sorry for late reply. Could you please share your test.json file?

      • Adrian Herrera Montenegro

        It does not allow me to post the json file. I think the problem with my json file is that all the content is between [], I used a file that has the content between {} and it works fine.

        • Try this sample JSON file content:

          {
    "tutorials": {
        "id": "Crunchify",
        "topic": "REST Service",
        "description": "This is REST Service Example by Crunchify."
    }
}
        • ashok

          can we import json into db like {
          “Company List”: [{
          “Name”: “crunchify.com”,
          “Author”: “App Shah”,
          “Compnay”: “Paypal”
          }, {
          “Name”: “json richards”,
          “Author”: “App L”,
          “Compnay”: “Google”
          }]
          }

  • And if my companyList its a array of arrays? how can I read it?

    • Bob

      you need to parse it like it is array of array, basically two loops to iterate the arrays.

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