Archives: JSONObject

Android Realm – Insert JSON Object

February 20, 2017 | By Prasanna Sherekar | Post comment

Realm Insert JSON Object Example in Android and Java – Realm Database

— You can add a JSON object that maps to a RealmObject to Realm.
— The JSON object can be a String, a JSONObject or an InputStream.
— Realm will ignore any properties in the JSON not defined by the RealmObject.

// A RealmObject that represents a city
public class City extends RealmObject {
 private String city;
 private int id;
 // getters and setters...
}

// Insert from a JSON String
try (Realm realm = Realm.getDefaultInstance()) {
 realm.executeTransaction(real -> {
  real.createObjectFromJson(City.class, "{ city: \"Amravati\", id: 1 }");
 });
}

// Insert multiple JSON items using an InputStream
try (Realm realm = Realm.getDefaultInstance()) {
 realm.executeTransaction(real -> {
  try {
   InputStream inputStream = new FileInputStream(new File("path_to_json_file"));
   real.createAllFromJson(City.class, inputStream);
  } catch (IOException e) {
   throw new RuntimeException(e);
  }
 });
}

// A RealmObject that represents a city

public class City extends RealmObject {

private String city;

private int id;

// getters and setters...

}

// Insert from a JSON String

try (Realm realm = Realm.getDefaultInstance()) {

realm.executeTransaction(real -> {

real.createObjectFromJson(City.class, "{ city: \"Amravati\", id: 1 }");

});

}

// Insert multiple JSON items using an InputStream

try (Realm realm = Realm.getDefaultInstance()) {

realm.executeTransaction(real -> {

try {

InputStream inputStream = new FileInputStream(new File("path_to_json_file"));

real.createAllFromJson(City.class, inputStream);

} catch (IOException e) {

throw new RuntimeException(e);

}

});

}

Java – Read JSON Data Simple Example

May 30, 2010 | By Prasanna Sherekar | Post comment

In below example, it uses JSONParser to read and display JSON data from a file named “test.json“ using JSON.simple, a simple Java library for JSON processing.

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Iterator;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

public class JsonSimpleExample {
    public static void main(String[] args) {

        JSONParser parser = new JSONParser();

        try {

            Object obj = parser.parse(new FileReader("c:\\test.json"));

            JSONObject jsonObject = (JSONObject) obj;

            String name = (String) jsonObject.get("name");
            System.out.println(name);

            long age = (Long) jsonObject.get("age");
            System.out.println(age);

            // loop array
            JSONArray msg = (JSONArray) jsonObject.get("messages");
            Iterator < String > iterator = msg.iterator();
            while (iterator.hasNext()) {
                System.out.println(iterator.next());
            }

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ParseException e) {
            e.printStackTrace();
        }

    }

}

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.IOException;

import java.util.Iterator;

import org.json.simple.JSONArray;

import org.json.simple.JSONObject;

import org.json.simple.parser.JSONParser;

import org.json.simple.parser.ParseException;

public class JsonSimpleExample {

public static void main(String[] args) {

JSONParser parser = new JSONParser();

try {

Object obj = parser.parse(new FileReader("c:\\test.json"));

JSONObject jsonObject = (JSONObject) obj;

String name = (String) jsonObject.get("name");

System.out.println(name);

long age = (Long) jsonObject.get("age");

System.out.println(age);

// loop array

JSONArray msg = (JSONArray) jsonObject.get("messages");

Iterator < String > iterator = msg.iterator();

while (iterator.hasNext()) {

System.out.println(iterator.next());

}

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

} catch (ParseException e) {

e.printStackTrace();

}

Output:

prasanna
25
msg 1
msg 2
msg 3

Java – Write JSON Data Simple Example

May 25, 2010 | By Prasanna Sherekar | Post comment

In below example, it writes JSON data via JSONObject and JSONArray, and save it into a file named “test.json“ using JSON.simple, a simple Java library for JSON processing.

import java.io.FileWriter;
import java.io.IOException;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;

public class JsonSimpleExample {
    public static void main(String[] args) {

        JSONObject obj = new JSONObject();
        obj.put("name", "prasanna");
        obj.put("age", new Integer(25));

        JSONArray list = new JSONArray();
        list.add("msg 1");
        list.add("msg 2");
        list.add("msg 3");

        obj.put("messages", list);

        try {

            FileWriter file = new FileWriter("c:\\test.json");
            file.write(obj.toJSONString());
            file.flush();
            file.close();

        } catch (IOException e) {
            e.printStackTrace();
        }

        System.out.print(obj);

    }

}

import java.io.FileWriter;

import java.io.IOException;

import org.json.simple.JSONArray;

import org.json.simple.JSONObject;

public class JsonSimpleExample {

public static void main(String[] args) {

JSONObject obj = new JSONObject();

obj.put("name", "prasanna");

obj.put("age", new Integer(25));

JSONArray list = new JSONArray();

list.add("msg 1");

list.add("msg 2");

list.add("msg 3");

obj.put("messages", list);

try {

FileWriter file = new FileWriter("c:\\test.json");

file.write(obj.toJSONString());

file.flush();

file.close();

} catch (IOException e) {

e.printStackTrace();

}

System.out.print(obj);

}

Output: (see content of file “test.json”)

{
“age”:25,
“name”:”prasanna”,
“messages”:[“msg 1″,”msg 2″,”msg 3”]
}