We Keep Coding

Parse a URI String into a JSON object

I've got the URI like this:
http://localhost:8080/profile/55cbd?id=123&type=product&productCategories.id=ICTLicense&productCategories.name.firstName=Jack&productCategories.name.lastName=Sparrow&groups=a&groups=b
I need a JSON object like this:
{
"id": "123",
"type": "product",
"productCategories": {
"id": "ICTlicense",
"name": {
"firstName": "Jack",
"lastName": "Sparrow"
}
},
"groups":["a", "b"]
}
Query parameters nesting can be dynamic, like for example abc.def.ghi.jkl.mno=value1&abc.xyz=value2 will result in
{
"abc": {
"def": {
"ghi": {
"jkl": {
"mno": "value1"
}
}
},
"xyz": "value2"
}
}
I have tried this but it can not handle the nesting.
final Map<String, String> map = Splitter.on('&').trimResults().withKeyValueSeparator('=').split(request.getQuery());
How to do this in Java?

With the way that your URI string is structured it wouldn't be possible to nest it the way you'd like, here's why.
id=123 This is simple enough since id would just be an int
productCategories.id=ICTLicense This would also be simple enough since we can assume that productCategories is an object and id is a key inside of the object
However, it gets more complex when you start using arrays, for instance:
&groups=a&groups=b
How do you know that groups is an array, and not simply a key called groups with a value of a or b
Also, you store all your data to Map<String, String>,
This wouldn't support arrays as it stores objects to key-value, so you wouldn't be able to have multiple keys of groups with different values.
I'd also suggest you use a library like Gson and parse your data to a JsonObject
https://github.com/google/gson
If you were to use Gson, you could do something similar to this:
public JsonObject convertToJson(String urlString) {
//Create a JsonObject to store all our data to
JsonObject json = new JsonObject();
//Split the data part of the url by the props
String[] props = urlString.split("&");
//Loop through every prop in the url
for (String prop : props) {
//Create a list of all the props and nested props
String[] nestedProps = prop.split("=")[0].split("\\.");
//Get the actual key for our prop
String key = nestedProps[nestedProps.length - 1];
//Get the value
String value = prop.split("=")[1];
//Loop through our props array
for (String nestedProp : nestedProps) {
//If the property already exists, then skip
if (json.has(nestedProp)) continue;
//If the prop is the key, add it to the json object
if(nestedProp.equalsIgnoreCase(key)) {
json.addProperty(nestedProp, value);
continue;
}
//If the above checks fail, then create an object in the json
json.add(nestedProp, new JsonObject());
}
}
return json;
}

How to construct this JSON array of JSONObjects

I have a Problem which I have to solve in Java.I have a data in YAML where the data is in this structure
600450:
STATE:STATE1
CITY:CITY1
ID:1
CONTACT:1234
600453:
STATE:STATE1
CITY:CITY1
ID:2
CONTACT:3456
600451:
STATE:STATE2
CITY:CITY2
ID:3
CONTACT:2234
.....
I converted this into JSONObject but I am strugling to change this into this JSONObject object where the structure should be of this form
{
STATE1:
{[
CITY1:{
[{ID:1,CODE:600450,CONTACT:1234},
{ID:2,CODE:600453,CONTACT:3456}
]
},
CITY2:{
[
{ID:3,CODE:600451,CONTACT:1234}
]
}
]}
}
I have almost lost a hour by doing different Things with JSONObject and JSONArray and then switched to HashMap and ArrayList of HashMap but I am not able to get it !
This was my try I am sure this is absurd I know that How to achieve this in Java .

Assuming that your converted initial JSON looks like this:
{
"600450": {
"STATE": "STATE1",
"CITY": "CITY1",
"ID": 1,
"CONTACT": 1234
},
"600451": {
"STATE": "STATE2",
"CITY": "CITY2",
"ID": 3,
"CONTACT": 2234
},
"600453": {
"STATE": "STATE1",
"CITY": "CITY1",
"ID": 2,
"CONTACT": 3456
}
}
Here is a static method that does the full conversion to your desired format:
static JSONObject convert(JSONObject initial) {
// STATE -> CITY -> Address[]
Map<String, Map<String, List<Map<String, Object>>>> stateToCityToAddresses = new HashMap<>();
// Get list of codes
String[] codes = JSONObject.getNames(initial);
// Loop over codes - "600450", "600451", "600453", ...
for (String code : codes) {
// Get the JSONObject containing state data
JSONObject state = initial.getJSONObject(code);
// Extract information from state JSONObject
String stateName = state.getString("STATE");
String cityName = state.getString("CITY");
long id = state.getLong("ID");
long contact = state.getLong("CONTACT");
// Some Java 8 awesomeness!
List<Map<String, Object>> addresses = stateToCityToAddresses
.computeIfAbsent(stateName, sn -> new HashMap<>()) // This makes sure that there is a Map available to hold cities for a given state
.computeIfAbsent(cityName, cn -> new ArrayList<>()); // This makes sure that there is a List available to hold addresses for a given city
// Save data in a map representing a json object like: {"CONTACT":1234,"CODE":600450,"ID":1}
Map<String, Object> address = new HashMap<>();
address.put("ID", id);
address.put("CONTACT", contact);
address.put("CODE", Long.parseLong(code));
// Add the address under city
addresses.add(address);
}
// Just use the JSONObject.JSONObject(Map<?, ?>) constructor to get the final result
JSONObject result = new JSONObject(stateToCityToAddresses);
// You can sysout the result to see the data
// System.out.println(result);
return result;
}

Allow me to play Devil's Advocate.
I think you may risk deviating away from the relationships that have been described in the .yaml. You should try to avoid embedding any application-specific logic inside of your data models, since your assumptions may land you in trickier places in the future.
Generally speaking, you should respect the initial form of the data and interpret the relationships or associated logic with the flexibility of runtime processing. Otherwise, you end up serializing data structures which do not correlate directly with the source, and your assumptions may land you in a hot spot.
The "real" JSON equivalent, I suspect; would look something like this:
{
"600450": {
"STATE": "STATE1",
"CITY": "CITY1",
"ID": 1,
"CONTACT": 1234
},
"600453": { ...etc }
}
It would still be possible to pair these relationships. If you want to relate all Objects by city, you could first separate them into bins. You could do this by using a Map which relates a String city to a List of JSONObjects:
// This will be a Map of List of JSONObjects separated by the City they belong to.
final Map<String, List<JSONObject>> mCityBins = new ArrayList();
// Iterate the List of JSONObjects.
for(final JSONObject lJSONObject : lSomeListOfJSONObjects) {
// Fetch the appropriate bin for this kind of JSONObject's city.
List<JSONObject> lBin = mCityBins.get(lJSONObject.get("city"));
// Does the right bin not exist yet?
if (lBin == null) {
// Create it!
lBin = new ArrayList();
// Make sure it is in the Map for next time!
mCityBins.add(lJSONObject.get("city"), lBin);
}
// Add the JSONObject to the selected bin.
lBin.add(lJSONObject);
}
Whilst you process the JSONObjects, whenever you come across a city whose key does not exist in the Map, you can allocate a new List<JSONObject>, add the current item to that List and add it into the Map. For the next JSONObject you process, if it belongs to the same city, you'd find the existing List to add it to.
Once they're separated into bins, generating the corresponding JSON will be easy!

As I see your git repo you just try to convert first Json structure to new Structure you want. I must to tell you probably you could create this structure directly from YAML file.
As I don't see your first Json structure so I guess that must be something like this :
{600450:{STATE:STATE1 , CITY:CITY2 , ...} , ...}
If this is true so this way can help you :
public static JSONObject convert(JSONObject first) throws JSONException {
HashMap<String , HashMap<String , JSONArray>> hashMap = new HashMap<>();
Iterator<String> keys = first.keys();
while (keys.hasNext())
{
String key = keys.next();
JSONObject inner = first.getJSONObject(key);
String state = inner.getString("STATE");
HashMap<String , JSONArray> stateMap =
hashMap.computeIfAbsent(state , s -> new HashMap<>());
String city = inner.getString("CITY");
JSONArray array = stateMap.computeIfAbsent(city , s->new JSONArray());
JSONObject o = new JSONObject();
o.put("ID" , inner.getInt("ID"));
//in this section you could create int key by calling Integer.parse(String s);
o.put("CODE" , Integer.valueOf(key));
o.put("CONTACT" , inner.getInt("CONTACT"));
array.put(o);
}
JSONObject newStructureObject = new JSONObject();
for(String stateKey:hashMap.keySet())
{
JSONArray array = new JSONArray();
JSONObject cityObject = new JSONObject();
HashMap<String , JSONArray> cityMap = hashMap.get(stateKey);
for(String cityKey : cityMap.keySet())
{
cityObject.put(cityKey , cityMap.get(cityKey));
}
array.put(cityObject);
newStructureObject.put(stateKey , array);
}
return newStructureObject;
}

Get all Cassandra query result in JSON format Using Java API

Using query select JSON * from table_name in cqlsh I can get results in JSON format. I want to do the same using Datastax Java API.
StringBuilder sb = new StringBuilder("SELECT json * FROM ").append("JavaTest.data");
String query = sb.toString();
ResultSet rs = session.execute(query);
List<Row> rows = rs.all();
String q1 = rows.toString();
System.out.println(q1);
But the result is :
[
Row [
{
"id":1,
"time":"12",
"value":"SALAM"
}
],
Row [
{
"id":2,
"time":" 89",
"value":" BYE"
}
],
Row [
{
"id":3,
"time":" 897",
"value":" HelloWorld"
}
]
]
that it is not in the correct JSON format. I know I can get the JSON of a row but in that way, I should use a loop to get all results in JSON format. Searching in JAVA API Docs I couldn't find any solution for this!

you need to use following - just get JSON strings as is:
for (Row row : rs) {
String json = row.getString(0);
// ... do something with JSON string
}
If you want to represent them as the list of objects, then it could be easier to add square brackets before & after iteration, and put comma between JSON objects, like this:
ResultSet rs = session.execute("select json * from test.jtest ;");
int i = 0;
System.out.print("[");
for (Row row : rs) {
if (i > 0)
System.out.print(",");
i++;
String json = row.getString(0);
System.out.print(json);
}
System.out.println("]");
Or you can write custom serializer for ResultSet, and put conversion task into it:
ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule();
module.addSerializer(ResultSet.class, new ResultSetSerializer());
mapper.registerModule(module);
rs = session.execute("select * from test.jtest ;");
String json = mapper.writeValueAsString(rs);
System.out.println("'" + json + "'");
This is much more complex task (you need correctly handle collections, user-defined types etc.), but you may have better control over serialization.
Full code is available at this gist. Please note that JSON serializer handles only NULL, boolean & int types - everything else is treated as string. But it's enough to understand an idea.

How to rename key in JSONObject using java?

I want to rename the keys of a JSON object using Java.
My input JSON is:
{
"serviceCentreLon":73.003742,
"type":"servicecentre",
"serviceCentreLat":19.121737,
"clientId":"NMMC01"
}
I want to change it to:
{
"longitude":73.003742,
"type":"servicecentre",
"latitude":19.121737,
"clientId":"NMMC01"
}
i.e. I want to rename "serviceCentreLon" to "longitude" and "serviceCentreLat" to "latitude". I am using the JSONObject type in my code.

Assuming you're using the json.org library: once you have a JSONObject, why not just do this?
obj.put("longitude", obj.get("serviceCentreLon"));
obj.remove("serviceCentreLon");
obj.put("latitude", obj.get("serviceCentreLat"));
obj.remove("serviceCentreLat");
You could create a rename method that does this (then call it twice), but that's probably overkill if these are the only fields you're renaming.

String data= json.toString();
data=data.replace("serviceCentreLon","longitude");
data=data.replace("serviceCentreLat","latitude");
convert back to json object

I'm not sure whether I get your question right, but shouldn't the following work?
You could use a regular expression to replace the keys, for example:
String str = myJsonObject.toString();
str = str.replace(/"serviceCentreLon":/g, '"longitude":');
str = str.replace(/"serviceCentreLat":/g, '"latitude":');
It's not as "clean", but it might get the job done fast.

To build on Danyal Sandeelo's approach, instead of:
data=data.replace("serviceCentreLon","longitude");
use
data=data.replace("\"serviceCentreLon\":","\"longitude\":");
This method explicitly matches the json key syntax, and avoids obscure errors where the key value is present as valid data elsewhere in the json string.

The best way to approach the problem is to parse the JSON data and then replace the key. A number of parsers are available - google gson, Jackson serializer de-serializers, org.json.me are a few such java libraries to handle JSON data.
http://www.mkyong.com/java/how-do-convert-java-object-to-from-json-format-gson-api/
is a good way to deal with it if you have a pretty generic and relatively huge JSON data. Of course, you have to spend time in learning the library and how to use it well.
http://www.baeldung.com/jackson-map is another such parser.
https://stleary.github.io/JSON-java/ is the simplest one especially if you don't want any serious serialization or deserialization

Have an object that maps to this object data structure.
Use GSON parser or Jackson parser to convert this json into POJO.
Then map this object to another Java Object with required configuration
Convert that POJO back to json using the same GSON parsers.
refer this for further reference
http://www.mkyong.com/java/how-do-convert-java-object-to-from-json-format-gson-api/

I faced this problem during my work so I've made a useful Utils class and I want to share it with you.
package net.so.json;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import org.json.JSONObject;
public class Utils {
/**
* replace json object keys with the new one
* #param jsonString represents json object as string
* #param oldJsonKeyNewJsonKeyMap map its key old json key & its value new key name if nested json key you have traverse
* through it using . example (root.coutry, count) "root.country" means country is a key inside root object
* and "count" is the new name for country key
* Also, if the value for the map key is null, this key will be removed from json
*/
public static void replaceJsonKeys(final JSONObject jsonObject, final Map<String, String> oldJsonKeyNewJsonKeyMap) {
if (null == jsonObject || null == oldJsonKeyNewJsonKeyMap) {
return;
}
// sort the old json keys descending because we want to replace the name of the inner most key first, then
// the outer one
final List<String> oldJsonKeys = oldJsonKeyNewJsonKeyMap.keySet().stream().sorted((k2, k1) -> k1.compareTo(k2)).collect(Collectors.toList());
oldJsonKeys.forEach(k -> {
// split old key, remember old key is something like than root.country
final String[] oldJsonKeyArr = k.split("\\.");
final int N = oldJsonKeyArr.length;
// get the object hold that old key
JSONObject tempJsonObject = jsonObject;
for (int i = 0; i < N - 1; i++)
tempJsonObject = tempJsonObject.getJSONObject(oldJsonKeyArr[i]);
final String newJsonKey = oldJsonKeyNewJsonKeyMap.get(k);
// if value of the map for a give old json key is null, we just remove that key from json object
if (!"null".equalsIgnoreCase(newJsonKey))
tempJsonObject.put(newJsonKey, tempJsonObject.get(oldJsonKeyArr[N - 1]));
// remove the old json key
tempJsonObject.remove(oldJsonKeyArr[N - 1]);
});
}
}
you can test this class by running App
package net.so.json;
import java.util.HashMap;
import java.util.Map;
import org.json.JSONObject;
public class App {
public static void main(String[] args) {
final String jsonString = "{\"root\":{\"country\": \"test-country\", \"city\": \"test-city\"}}";
final JSONObject jsonObject = new JSONObject(jsonString);
System.out.println("json before replacement: " + jsonObject);
/* will get >>
{
"root": {
"country": "test-country",
"city": "test-city"
}
}
*/
// construct map of key replacements
final Map<String, String> map = new HashMap<>();
map.put("root", "root2");
map.put("root.country", "count");
map.put("root.city", "null"); // null as a value means we want to remove this key
Utils.replaceJsonKeys(jsonObject, map);
System.out.println("json after replacement: " + jsonObject);
/* will get >>
{
"root2": {
"count": "test-country"
}
}
*/
}
}

I ran into a scenario where I wanted to remove a hyphen from an unknown number of keys in a nested object.
So this:
{
"-frame": {
"-shape": {
"-rectangle": {
"-version": "1"
}
},
"-path": {
"-geometry": {
"-start": {
"-x": "26.883513064453602",
"-y": "31.986310940359715"
}
},
"-id": 1,
"-type": "dribble",
"-name": "MultiSegmentStencil",
"-arrowhead": "0"
}
}
}
Would be this:
{
"frame": {
"shape": {
"rectangle": {
"version": "1"
}
},
"path": {
"geometry": {
"start": {
"x": "26.883513064453602",
"y": "31.986310940359715"
}
},
"id": 1,
"type": "dribble",
"name": "MultiSegmentStencil",
"arrowhead": "0"
}
}
}
A recursive method(kotlin).. with a list did the trick via Jackson
fun normalizeKeys(tree: JsonNode, fieldsToBeRemoved: MutableList<String>) {
val node = tree as ContainerNode<*>
val firstClassFields = node.fields()
while(firstClassFields.hasNext()) {
val field = firstClassFields.next()
if(field.key.substring(0,1) == "-") {
fieldsToBeRemoved.add(field.key)
}
if(field.value.isContainerNode) {
normalizeKeys(field.value, fieldsToBeRemoved)
}
}
fieldsToBeRemoved.forEach {
val fieldByKey: MutableMap.MutableEntry<String, JsonNode>? = getFieldByKey(tree, it)
if(fieldByKey != null) {
(tree as ObjectNode)[fieldByKey!!.key.replaceFirst("-","")] = fieldByKey.value
(tree as ObjectNode).remove(fieldByKey!!.key)
}
}
}

MongoDB get data into java object

I am quite new to MongoDb. i use a find and get the result in JSON format.
{"Name": "Harshil", "Age":20}
so what i need is parse this in java and get values in the variables.
String name should contain Harshil
int age should contain 20
is there a way to store these details in JAVA object?

Here is how to connect to the your MongoDB:
MongoClient client = new MongoClient("localhost",27017); //with default server and port adress
DB db = client.getDB( "your_db_name" );
DBCollection collection = db.getCollection("Your_Collection_Name");
After the connecting you can pull your data from the server.Below, i assume that your document has Name and Age field :
DBObject dbo = collection.findOne();
String name = dbo.get("Name");
int age = dbo.get("Age");

Take a look at GSON library. It converts JSON to Java objects and vice-versa.

There are many ways and tools, one of which is gson
class Person {
private String name;
private int age;
public Person() {
// no-args constructor
}
}
Gson gson = new Gson();
Person person = gson.fromJson(json, Person.class);
And I'd feel lax if I didn't add this link too.

You can just do it with the Java driver :
DBObject dbo = ...
String s = dbo.getString("Name")
int i = dbo.getInt("Age")
Using another framework on top of the Java driver should be considered I you have multiple objects to manage.

As we don't want to use the deprecated methods so, you can use the following code to do so:
MongoClient mongo = new MongoClient( "localhost" , 27017 );
MongoDatabase database = mongo.getDatabase("your_db_name");
MongoCollection<Document> collection = database.getCollection("your_collection_name");
FindIterable<Document> iterDoc = collection.find();
MongoCursor<Document> dbc = iterDoc.iterator();
while(dbc.hasNext()){
try {
JsonParser jsonParser = new JsonFactory().createParser(dbc.next().toJson());
ObjectMapper mapper = new ObjectMapper();
Person person = mapper.readValue(jsonParser, Person.class);
String name = person.get("Name");
String age = person.get("Age");
} catch (Exception e){
e.printStackTrace();
}
JsonFactory, JsonParser,etc. are being used from Jackson to de-serialize the Document to the related Entity object.

Have you considere Morphia?
#Entity
class Person{
#Property("Name") Date name;
#Property("Age") Date age;
}

I would prefer using the new Mongodb Java API. It's very clean and clear.
public MyEntity findMyEntityById(long entityId) {
List<Bson> queryFilters = new ArrayList<>();
queryFilters.add(Filters.eq("_id", entityId));
Bson searchFilter = Filters.and(queryFilters);
List<Bson> returnFilters = new ArrayList<>();
returnFilters.add(Filters.eq("name", 1));
Bson returnFilter = Filters.and(returnFilters);
Document doc = getMongoCollection().find(searchFilter).projection(returnFilter).first();
JsonParser jsonParser = new JsonFactory().createParser(doc.toJson());
ObjectMapper mapper = new ObjectMapper();
MyEntity myEntity = mapper.readValue(jsonParser, MyEntity.class);
return myEntity;
}
Details at
http://ashutosh-srivastav-mongodb.blogspot.in/2017/09/mongodb-fetch-operation-using-java-api.html

Newer Way [Since getDB() is Deprecated]
Since the original answer was posted the DBObject and corresponding method client.getDB have been deprecated. For anyone who may be looking for a solution since the new update I have done my best to translate.
MongoClient client = new MongoClient("localhost",27017); //Location by Default
MongoDatabase database = client.getDatabase("YOUR_DATABASE_NAME");
MongoCollection<Document> collection = database.getCollection("YOUR_COLLECTION_NAME");
Once connected to the document there are numerous familiar methods of getting data as a Java Object. Assuming you plan to have multiple documents that contain a persons name and their age I suggest collecting all the documents (which you can visualize as rows containing a name and age) in an ArrayList then you can simply pick through the documents in the ArrayList to convert them to java objects as so:
List<Document> documents = (List<Document>) collection.find().into(new ArrayList<Document>());
for (Document document : documents) {
Document person = documents.get(document);
String name = person.get("Name");
String age = person.get("Age");
}
Honestly the for loop is not a pretty way of doing it but I wanted to help the community struggling with deprecation.

Try Using this function to convert JSON returned by mongodb to your custom java object list.
MongoClient mongodb = new MongoClient("localhost", 27017);
DB db = mongodb.getDB("customData-database");
DBCursor customDataCollection = db.getCollection("customDataList").find();
List<CustomJavaObject> myCustomDataList = null; // this list will hold your custom data
JSON json = new JSON();
ObjectMapper objectMapper = new ObjectMapper();
try {
//this is where deserialiazation(conversion) takes place
myCustomDataList = objectMapper.readValue(json.serialize(customDataCollection),
new TypeReference<List<Restaurant>>() {
});
} catch (IOException e) {
e.printStackTrace();
}
CustomJavaObject:
public class CustomJavaObject{
//your json fields go here
String field1, field2;
int num;
ArrayList<String> attributes;
//....write relevantgetter and setter methods
}
sample json:
{
"field1": "Hsr Layout",
"field2": "www.google.com",
"num": 20,
"attributes": [
"Benagaluru",
"Residential"
]
},
{
"field1": "BTM Layout",
"field2": "www.youtube.com",
"num": 10,
"attributes": [
"Bangalore",
"Industrial"
]
}