Develop Reference

How to name a JSON?

This is my code
List<Object[]> list = query.list();
List<JSONObject> result = new ArrayList<>();
for (Object[] rows : list) {
String buildingId = rows[0].toString();
String floorId = rows[1].toString();
String routerId = rows[2].toString();
String routerName = rows[3].toString();
Map<String, List<String>> floorMap = buildingMap.get(buildingId);
if(floorMap == null) {
floorMap = new HashMap<>();
}
......
}
What i need JSON format is like this
"buildings":{
"building_id":"3"={
"floor_id":"21"=[
"router_id":"3"
]
},
"building_id":"2"={
"floor_id":"20"=[
"router_id":"1101",
"router_id":"1102",
"router_id":"0",
"router_id":"1104",
"router_id":"1106"
],
"floor_id":"17"=[
"router_id":"1111",
"router_id":"1112",
"router_id":"1113"
]
},
"building_id":"1"={
"floor_id":"10"=[
"router_id":"1"
]
}
}
But now i'm getting like this
{
3={
21=[
3
]
},
2={
20=[
1101,
1102,
0,
1104,
1106
],
17=[
1111,
1112,
1113,
]
},
1={
10=[
1
]
}
}
thanks in advance

List<Object[]> list = query.list();
Gson gson = new Gson();
// convert your list to json
String jsonList = gson.toJson(list);
you need Gson Jar and simply you can convert list into json string.

My senior gave this code and finally it worked for me
`#Override
public String getFullRouterList() throws Exception {
//Format
// -- building map with building_id and floor map
// -- floor map with floor_id and list of routers
Map<String, Map<String, List<String>>> buildingMap = new HashMap<>();
System.out.println("in dao of getFullRouterList ");
session = sessionFactory.openSession();
tx = session.beginTransaction();
String sql = "SELECT building_id, floor_id, router_id, router_name FROM iot_trackbit.router_details";
SQLQuery query = session.createSQLQuery(sql);
List<Object[]> list = query.list();
List<JSONArray> result = new ArrayList<>();
for (Object[] rows : list) {
String buildingId = rows[0].toString();
String floorId = rows[1].toString();
String routerId = rows[2].toString();
String routerName = rows[3].toString();
Map<String, List<String>> floorMap = buildingMap.get(buildingId);
if(floorMap == null) {
floorMap = new HashMap<>();
}
List<String> routerList = floorMap.get(floorId);
if(routerList == null) {
routerList = new ArrayList<>();
}
routerList.add(routerId);
floorMap.put(floorId, routerList);
buildingMap.put(buildingId, floorMap);
System.out.println(buildingMap.keySet());
System.out.println(buildingMap);
}
JSONObject finalObj = new JSONObject();
JSONArray buildingsArr = new JSONArray();
for(String buildingId : buildingMap.keySet()) {
JSONObject buildingObject = new JSONObject();
Map<String, List<String>> floorMap = (HashMap<String, List<String>>) buildingMap.get(buildingId);
//{"1":["router1","router2","router3"]}
JSONArray floorsArr = new JSONArray();
for(String floorId : floorMap.keySet()) {
JSONObject floorObject = new JSONObject();
List<String> routerList = floorMap.get(floorId);
//["router1","router2"]
JSONArray array = new JSONArray();
for(String routerId : routerList) {
JSONObject routerObj = new JSONObject();
routerObj.put("id",routerId);
array.add(routerObj);
}
floorObject.put("id",floorId);
floorObject.put("routers", array);
floorsArr.add(floorObject);
}
buildingObject.put("id", buildingId);
buildingObject.put("floors", floorsArr);//floors array
buildingsArr.add(buildingObject);
finalObj.put("buildings",buildingsArr);
}
System.out.println("finalObj.toJSONString() : " +finalObj.toJSONString());
tx.commit();
session.close();
return finalObj.toJSONString();
}`
Now im geting like this format
{
"buildings": [
{
"id": "3",
"floors": [
{
"id": "21",
"routers": [
{
"id": "3"
}
]
},
{
"id": "23",
"routers": [
{
"id": "0"
},
{
"id": "gateway123"
},
{
"id": "1001"
},
{
"id": "1002"
},
{
"id": "1003"
}
]
}
]
},
{
"id": "2",
"floors": [
{
"id": "20",
"routers": [
{
"id": "1101"
},
{
"id": "1102"
},
{
"id": "0"
},
{
"id": "1104"
},
{
"id": "1106"
},
{
"id": "1107"
},
{
"id": "1111"
},
{
"id": "1109"
},
{
"id": "1110"
}
]
},
{
"id": "17",
"routers": [
{
"id": "1111"
},
{
"id": "1112"
},
{
"id": "1113"
},
{
"id": "1114"
},
{
"id": "1115"
},
{
"id": "1116"
},
{
"id": "1117"
},
{
"id": "1118"
},
{
"id": "g1"
},
{
"id": "1119"
},
{
"id": "0"
}
]
},
{
"id": "18",
"routers": [
{
"id": "010101"
},
{
"id": "0"
}
]
}
]
},
{
"id": "1",
"floors": [
{
"id": "10",
"routers": [
{
"id": "1"
}
]
}
]
}
]
}`
Thanks for all

Java - How to get all the field names from JSON Schema

{
"type": "TestType",
"schema": {
"type": "object",
"properties": {
"field1": {
"format": "date",
"label": "field 1",
"type": "string"
},
"field2": {
"format": "date",
"label": "field 2",
"type": "string"
}
},
"required": [],
"additionalProperties": false
}
}
Hi Guys, I am new to JSON Schema, I just want to know how to define the Java model to mapping above JSON Schema, I want to get all the field name from the definition.
So it means that I want to parse the JSON Schema and return like this:
[field1, field2]
Note that the field list is automatic, may add more fields into the JSON Schema, field3, field4 ...

1.convert to JSONObject
2.save in List
3.convert List to Array
try this .
public void getKey(String response) {
List<String> keyList = new ArrayList<String>();
try {
JSONObject jsonObject = new JSONObject(response);
JSONObject schema = jsonObject.getJSONObject("schema");
JSONObject properties = schema.getJSONObject("properties");
Iterator iterator = properties.keys();
while (iterator.hasNext()) {
String key = iterator.next().toString();
keyList.add(key);
}
String[] arr = (String[]) keyList.toArray(new String[keyList.size()]);
} catch (JSONException e) {
e.printStackTrace();
}
}

I assume your json is in a String variable named var.
use org.json for the below code.
JSONObject jObj=new JSONObject(var);
ArrayList arr=new ArrayList();
for (Object keyObj: jObj.keySet())
{
String key = (String)keyObject;
arr.add(key);
}
That's it.
I have added maven dependency for org.json package for those who are working with maven!
<dependency>
<groupId>org.json</groupId>
<artifactId>json</artifactId>
<version>20160810</version>
</dependency>

Recursive solution that will work with nested objects
public Set<String> getMetadataSchemaFields(JsonNode metadataSchema) {
if (metadataSchema.has("properties")) {
val fields = new HashSet<String>();
metadataSchema.get("properties").fields().forEachRemaining(entry -> {
val nodeFields = getMetadataSchemaFields(entry.getValue());
if (nodeFields.isEmpty()) {
fields.add(entry.getKey());
} else {
nodeFields.forEach(nodeField -> fields.add(entry.getKey() + "/" + nodeField));
}
});
return fields;
} else {
return Set.of();
}
}

Parse nested Json object and store in database in Android

I just tried to get values that are stored in my JSON file and save it into sqlite database:
This is my JSON file:
{
"list": {
"meta": {
"count": 132,
"start": 0,
"type": "resource-list"
},
"resources": [
{
"resource": {
"classname": "Quote",
"fields": {
"date": "2017-03-16",
"price": 3.6720000000000002,
"type": "currency",
"symbol": "AED=X"
}
}
},
{
"resource": {
"classname": "Quote",
"fields": {
"date": "2017-03-16",
"price": 65.075000000000003,
"type": "currency",
"symbol": "AFN=X"
}
}
},
{
.............
}
............
I have tried like this but getting exception :
JSONObject mainObj = null;
try {
mainObj = new JSONObject(JSON);
JSONObject getSth = mainObj.getJSONObject("list");
if(mainObj != null){
JSONArray list = getSth.getJSONArray("resources");
if(list != null){
for(int i = 0; i < list.length();i++){
JSONObject elem = list.getJSONObject(i);
if(elem != null){
JSONObject prods = elem.getJSONObject("fields");
Object level = prods.get("type");
Toast.makeText(getApplicationContext(),""+level.toString(),Toast.LENGTH_LONG).show();
}
}
}
}
}catch (Exception e){
Toast.makeText(getApplicationContext(),""+e.toString(),Toast.LENGTH_LONG).show();
}
I was getting exception : no values in fields...
And pls give some suggestions that storing these values in Database table(matrotable) of(row fields) name, prize, symbol and type, I may try by making String Array and retrieving and storing the values for sqlite, is there any other easy options...
thanks

your fields objects are inside resource object so do
for(int i = 0; i < list.length();i++){
JSONObject elem = list.getJSONObject(i);
if(elem != null){
JSONObject prods = elem.getJSONObject("resource")
.getJSONObject("fields");
Object level = prods.get("type");
Toast.makeText(getApplicationContext(),""+level.toString(),Toast.LENGTH_LONG).show();
}
}
"resources": [ // resources list
{ // object i
"resource": { // fields are inside "resource" object
"classname": "Quote",
"fields": {
"date": "2017-03-16",
"price": 3.6720000000000002,
"type": "currency",
"symbol": "AED=X"
}
}
}

You are missing the resource JOSNObject parsing...
for(int i = 0; i < list.length();i++){
JSONObject elem = list.getJSONObject(i);
JSONObject resource = elem.getJSONObject("resource");
if(resource != null){
JSONObject prods = resource.getJSONObject("fields");
Object level = prods.get("type");
Toast.makeText(getApplicationContext(),""+level.toString(),Toast.LENGTH_LONG).show();
}
}

I recommend to you to use the simplest and easiest way to parse a json response to avoid this kind of issues:
1- generate your model classes by using this tool: http://www.jsonschema2pojo.org/ download and add the generated classes to your model package.
2- add this dependency to your gradle file:
compile 'com.google.code.gson:gson:2.4'
3- Call this method to parse your response:
Gson gson = new Gson();
ResponseModel responseModel = gson.fromJson(json, ResponseModel.class);

JAVA org.json not showing empty value

Here is my JAVA JSON code
#GET
#Consumes("application/x-www-form-urlencoded")
#Path("/getAllEmp")
public Response GetAllEmp() {
JSONObject returnJson = new JSONObject();
try {
ArrayList<Emp_Objects> objList = new ArrayList<Emp_Objects>();
DBConnection conn = new DBConnection();
objList = conn.GetEmpDetails();
JSONArray empArray = new JSONArray();
if (!objList.isEmpty()) {
GetLocation loc = new GetLocation();
for (Emp_Objects obj : objList) {
JSONObject jsonObj = new JSONObject();
jsonObj.put("id", obj.id);
jsonObj.put("name", obj.name);
jsonObj.put("email", obj.email);
jsonObj.put("address", obj.address);
empArray.put(jsonObj);
}
}
returnJson.put("data", empArray);
} catch (Exception e) {
}
return Response.ok(returnJson.toString()).header("Access-Control-Allow-Origin", "*").build();
}
When i execute this it gives me the following json
{
"data": [{
"id": 1,
"name": "123_name"
}, {
"id": 2,
"name": "321_name",
"email": "xyz#asd.com"
}]
}
In the above json email and address are missing because email and address is null on database.
So can i show json with empty value like following
{
"data": [{
"id": 1,
"name": "123_name",
"email": "",
"address": ""
}, {
"id": 2,
"name": "321_name",
"email": "",
"address": ""
}]
}
I am using JAVA and org.json with MySQL database.

If the objects are null, insert an empty String instead.
jsonObj.put("email", obj.email == null ? "" : obj.email);
jsonObj.put("address", obj.address == null ? "" : obj.address);
If you have a larger amount of rows to process, I recommend you to turn this is to a function for better readability and to save you some time.
jsonObj.put("email", nullToEmpty(obj.address));
private String nullToEmpty(String arg) {
return arg == null ? "" : arg;
}

Trouble with Parsing JSONObject in java

I am having trouble parsing this particular JSONObject,
Here is the object:
{"status":1,"dds":{"id":1,"name":"DDS1","description":"This is DDS 1","children":[{"id":2,"order":1,"type":1,"children":[{"id":3,"order":1,"type":3,"children":[]},{"id":4,"order":2,"type":2,"children":[]}]}]}}
That object is stored in my variable called result, here is my code to parse it:
JSONObject jsonObj = null;
JSONArray jsonArr = null;
try {
jsonObj = new JSONObject(result);
jsonArr = jsonObj.getJSONArray("dds");
} catch (JSONException e) {
e.printStackTrace();
}
And it is giving me this error:
org.json.JSONException: Value {"id":1,"children":[{"type":1,"order":1,"id":2,"children":[{"type":3,"order":1,"id":3,"children":[]},{"type":2,"order":2,"id":4,"children":[]}]}],"description":"This is DDS 1","name":"DDS1"} at dds of type org.json.JSONObject cannot be converted to JSONArray
I am trying to break it up into sub arrays of children. Where am I going wrong?
#Mr Love
here is my output to your code

You are calling jsonArr = jsonObj.getJSONArray("dds");, however dds is not an array, it's a JSON object, if you format the JSON you can see it clearly:
{
"status":1,
"dds":{
"id":1,
"name":"DDS1",
"description":"This is DDS 1",
"children":[
{
"id":2,
"order":1,
"type":1,
"children":[
{
"id":3,
"order":1,
"type":3,
"children":[
]
},
{
"id":4,
"order":2,
"type":2,
"children":[
]
}
]
}
]
}
}
So you will just need to call JSONObject dds = jsonObj.getJSONObject("dds"), and if you want the children you would call JSONArray children = jsonObj.getJSONObject("dds").getJSONArray("children");.
private static final String json = "{\"status\":1,\"dds\":{\"id\":1,\"name\":\"DDS1\",\"description\":\"This is DDS 1\",\"children\":[{\"id\":2,\"order\":1,\"type\":1,\"children\":[{\"id\":3,\"order\":1,\"type\":3,\"children\":[]},{\"id\":4,\"order\":2,\"type\":2,\"children\":[]}]}]}}";
public static void main(String[] args) throws JSONException
{
JSONObject jsonObj = new JSONObject(json);
JSONObject dds = jsonObj.getJSONObject("dds");
JSONArray children = dds.getJSONArray("children");
System.out.println("Children:");
System.out.println(children.toString(4));
JSONArray grandChildren = children.getJSONObject(0).getJSONArray("children");
System.out.println("Grandchildren:");
System.out.println(grandChildren.toString(4));
}
Produces:
Children:
[{
"children": [
{
"children": [],
"id": 3,
"order": 1,
"type": 3
},
{
"children": [],
"id": 4,
"order": 2,
"type": 2
}
],
"id": 2,
"order": 1,
"type": 1
}]
Grandchildren:
[
{
"children": [],
"id": 3,
"order": 1,
"type": 3
},
{
"children": [],
"id": 4,
"order": 2,
"type": 2
}
]

You can do it like this, where the JsonElement could be a JSONobject or JsonArray or any primitive type:
private JsonElement findElementsChildren(JsonElement element, String id) {
if(element.isJsonObject()) {
JsonObject jsonObject = element.getAsJsonObject();
if(id.equals(jsonObject.get("id").getAsString())) {
return jsonObject.get("children");
} else {
return findElementsChildren(element.get("children").getAsJsonArray(), id);
}
} else if(element.isJsonArray()) {
JsonArray jsonArray = element.getAsJsonArray();
for (JsonElement childElement : jsonArray) {
JsonElement result = findElementsChildren(childElement, id);
if(result != null) {
return result;
}
}
}
return null;
}