JSON Samples in Java

Sample 1:- Using  json-lib library

Transforming beans, maps, collections, java arrays and XML to JSON and back again to beans and DynaBeans.

• Exporting to JSON

Export.java 

import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import net.sf.json.JSONObject;

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

  Map<String,String> map = new HashMap<String,String>();
  map.put("name", "Mohammed");
  map.put("empid", "E-1097");
  map.put("phone", "123456789");

  JSONObject json = new JSONObject();
  json.accumulateAll(map);

  List<String> list = new ArrayList<String>();
  list.add("JAVA");
  list.add("JSON");
  list.add("JSF");
  list.add("HIBERNATE");

  json.accumulate("technology", list);
  System.out.println(json.toString());
  try {
   FileWriter file = new FileWriter("d:\\sample.json");
   file.write(json.toString());
   file.flush();
   file.close();
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
}

 OUTPUT:-
{
   "name":"Mohammed",
   "empid":"E-1097", 
   "phone":"123456789",
   "technology":["JAVA","JSON","JSF","HIBERNATE"]
} 

• Importing from JSON

Import.java 

import java.io.BufferedReader;
import java.io.FileReader;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

public class Import {
 public static void main(String[] args) {
  try {
   FileReader fin = new FileReader("d:\\sample.json");
   BufferedReader bin = new BufferedReader(fin);
   StringBuilder sb = new StringBuilder();
   String b;
   while ((b = bin.readLine()) != null) {
    sb.append(b);
   }

   JSONObject jobj = JSONObject.fromObject(sb.toString());
   System.out.println(jobj.get("name"));
   System.out.println(jobj.get("empid"));
   System.out.println(jobj.get("phone"));
   JSONArray jarr = jobj.getJSONArray("technology");
   for (int i = 0; i < jarr.size(); i++)
    System.out.print(jarr.getString(i) + " ");

  } catch (Exception ex) {
   ex.printStackTrace();
  }
 }
}

OUTPUT:- 

Mohammed
E-1097
123456789
JAVA JSON JSF HIBERNATE

Sample 2 :- Using  Google Gson library

To convert Java objects to JSON and vice-versa

• Java Class

Data.java

package com.sajadhaja.gson;

import java.util.List;

public class Data {
 private String title;
 private int id;
 private boolean children;
 private List<Data> groups;

 public Data(String title, int id, boolean children, List<Data> groups) {
  this.title = title;
  this.id = id;
  this.children = children;
  this.groups = groups;
 }
 public Data(String title, int id, boolean children) {
  this.title = title;
  this.id = id;
  this.children = children;
 }
 public String getTitle() {
  return title;
 }
 public int getId() {
  return id;
 }
 public boolean getChildren() {
  return children;
 }
 public List<Data> getGroups() {
  return groups;
 }
 public void setTitle(String title) {
  this.title = title;
 }
 public void setId(int id) {
  this.id = id;
 }
 public void setChildren(boolean children) {
  this.children = children;
 }
 public void setGroups(List<Data> groups) {
  this.groups = groups;
 }
 public String toString() {
  return String.format("title:%s\n id:%d\n children:%s\n groups:%s", title, id,
    children, groups);
 }
}

• Exporting to JSON

Export.java

package com.sajadhaja.gson;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import com.google.gson.Gson;

public class Export {
 public static void main(String[] args) {
  try {
   List<Data> l = new ArrayList<Data>();
   List<Data> listnodata = new ArrayList<Data>();
   Data dchild = new Data("Child", 122, false, listnodata);
   l.add(dchild);
   Data d = new Data("Parent", 111, true, l);
   String jstr = new Gson().toJson(d);

   FileWriter file = new FileWriter("d:\\samplegs.json");
   file.write(jstr);
   file.flush();
   file.close();

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

OUTPUT:- 

{
"title":"Parent",
"id":111,
"children":true,
"groups":[
               {"title":"Child",
 "id":122,
 "children":false,
 "groups":[]
               }
             ]
}

• Importing from JSON

Import.java

package com.sajadhaja.gson;

import java.io.BufferedReader;
import java.io.FileReader;

import com.google.gson.Gson;

public class Import {
 public static void main(String args[]) {
  try {
   FileReader fin = new FileReader("d:\\samplegs.json");
   BufferedReader bin = new BufferedReader(fin);
   StringBuilder sb = new StringBuilder();
   String b;
   while ((b = bin.readLine()) != null) {
    sb.append(b);
   }
   System.out.println(sb.toString());
   Data data = new Gson().fromJson(sb.toString(), Data.class);
   System.out.println(data.toString());
  } catch (Exception ex) {
   ex.printStackTrace();
  }
 }
}

OUTPUT:- 

title:Parent,id:111,children:true,groups:[title:Child,id:122,children:false,groups:[]]