Java: Get value from a Json string (Set<String>) - java

I'm using this method that returns a Set<String> but in fact what I got is a Json string like this
[
{
"id":"Id1"
},
{
"id":"Id2",
"title":"anyTitle"
}
]
My goal is to get the value of key "id". I've also made a java bean to map the data:
public class Data {
private String id;
private String title;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
}
I tryied to parse using gson but all I can get is an error: Cannot cast 'java.util.LinkedHashMap$LinkedKeyIterator' to 'com.google.gson.stream.JsonReader'
So, obviously I'm doing something wrong:
Set<String> availableData = getData(); //this method returns a json string
Iterator<String> itr = availableData.iterator();
while (itr.hasNext()) {
Gson gson = new Gson();
JsonParser parser = new JsonParser();
JsonObject object = (JsonObject) parser.parse(itr.next());
Data data = gson.fromJson(object, Data.class);
}
update: The actual error is: Type mismatch Can't assign com.google.common.collect.Maps$TransformedEntriesMap to java.lang.String

In that line you pass an iterator:
JsonObject object = (JsonObject) parser.parse((JsonReader) itr);
But you should pass a next element:
JsonObject object = (JsonObject) parser.parse(itr.next());
In addition you got an extra comma in you JSON.
You can replace the whole block with that line:
Data data = gson.fromJson(itr.next(),Data.class)

Use Jackson mapper. You can directly convert it into an object and retrieve through getters.
ObjectMapper objectMapper = new ObjectMapper();
String carJson =
"{ \"brand\" : \"Mercedes\", \"doors\" : 5 }";
try {
Car car = objectMapper.readValue(carJson, Car.class);
System.out.println("car brand = " + car.getBrand());
System.out.println("car doors = " + car.getDoors());
} catch (IOException e) {
e.printStackTrace();
}

So, following this related issue: https://github.com/seleniumhq/selenium-google-code-issue-archive/issues/5154, finally I map this using JSONArray and streams from java8
Set<String> availableData = getData();
JSONArray dataArray = new JSONArray(availableData);
List<Object> dataList = dataArray.toList();
Object o = dataList.stream()
.filter(c -> ((Map) c).get("id").toString().contains("Id1"))
.findFirst().orElse(null);
return ((Map)o).get("id").toString();

Maybe you want to known how to use Gson to unserialized json to java object.
Here are two ways I can give you.
public void parse() {
String jsonString = "[\n" +
" {\n" +
" \"id\":\"Id1\"\n" +
" },\n" +
" {\n" +
" \"id\":\"Id2\",\n" +
" \"title\":\"anyTitle\"\n" +
" }\n" +
"]";
Gson gson = new Gson();
// Use Gson Type
Type setType = new TypeToken<HashSet<Data>>(){}.getType();
Set<Data> dataSet = gson.fromJson(jsonString, setType);
// Print [Data{id='Id2', title='anyTitle'}, Data{id='Id1', title='null'}]
System.out.println(dataSet);
// Use Java Array
Data[] dataArray = gson.fromJson(jsonString, Data[].class);
// Print [Data{id='Id1', title='null'}, Data{id='Id2', title='anyTitle'}]
System.out.println(Arrays.toString(dataArray));
}

Related

Java - Get multiple JSON values and turn into String

How would I get all the "name" values and turn them into a String?
So for example if I'd do the following:
System.out.println(value[1]);
It would print out name1.
Here is what I have so far:
JSON:
[
{
"name":"name1"
},
{
"name":"name2",
"changedToAt":1470659096000
},
{
"name":"name3",
"changedToAt":1473435817000
}
]
Java code:
try {
String UUID = p.getUniqueId().toString();
String slimUUID = UUID.replace("-", "");
InputStream in = new URL("https://api.mojang.com/user/profiles/" + slimUUID + "/names").openStream();
String json = IOUtils.toString(in);
IOUtils.closeQuietly(in);
try {
JSONParser parser = new JSONParser();
JSONObject jsonparse = (JSONObject) parser.parse(json);
//get "name" values and turn into String
} catch (ParseException e) {
System.out.println(e.getMessage());
}
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
You need to iterate over array and accumulate all name values into array of Strings.
So below is working source code:
JsonArray jsonObject = new JsonParser()
.parse(json)
.getAsJsonArray();
List<String> names = new ArrayList<>();
for (JsonElement jsonElement : jsonObject) {
names.add(jsonElement.getAsJsonObject().get("name").getAsString());
}
//now you can use as you wish, by index
System.out.println(names.get(1));//returns "name2"
Using the URL from your comment and Java 8 Stream API I've built this main method:
public static void main(final String[] args) throws ParseException, MalformedURLException, IOException {
final String url = "https://api.mojang.com/user/profiles/c8570e47605948d3a3cbe3ec3a681cc0/names";
final InputStream in = new URL(url).openStream();
final String json = IOUtils.toString(in);
IOUtils.closeQuietly(in);
final JSONParser parser = new JSONParser();
final JSONArray jsonparse = (JSONArray) parser.parse(json);
System.out.println(jsonparse);
System.out.println();
final List<String> names = (ArrayList<String>) jsonparse.stream().map((obj) -> {
final JSONObject object = (JSONObject) obj;
return (String) object.getOrDefault("name", "");
}).peek(System.out::println).collect(Collectors.toList());
}
Try My library: abacus-common. All the above can be replaced with:
List<Map<String, Object>> resp = HttpClient.of("https://api.mojang.com/user/profiles/" + slimUUID + "/names").get(List.class);
List<String> names = resp.stream().map(m -> (String) (m.get("name"))).collect(Collectors.toList());
By the way, if slimUUID is equal to: UUID.randomUUID().toString().replaceAll("-", ""). It's be simplified:
List<Map<String, Object>> resp = HttpClient.of("https://api.mojang.com/user/profiles/" + N.guid()+ "/names").get(List.class);
List<String> names = resp.stream().map(m -> (String) (m.get("name"))).collect(Collectors.toList());

Extracting the value of an element from a JSON

I'm trying to make a test where I get some documents based on the id of the batch they belong to. More specifically, I want to check that a specific batchPublicId is in the response body. I am using okhttp for the test.
This a shorter version of the json:
{
"_embedded": {
"invoices": [
{
"type": "INVOICE",
"publicId": "27bc8426-17cf-4fe5-9278-64108ae05e4b",
"deliveryStatus": null,
"processingStatus": "INITIATED",
"batchPublicId": "0000000000000000000000001"
}
]
}
}
I'm new to json and this is how far I got with the problem:
String invoicesJsonData = response.body().string();
JSONObject invoicesJsonObject = new JSONObject(invoicesJsonData);
Assert.assertTrue(invoicesJsonObject.getJSONObject("_embedded") !=null && invoicesJsonObject.getJSONObject("_embedded").has("invoices"));
I would like to verify that batchPublicId has the value mentioned in the json. Is there a way to do this? Thank you.
String invoicesJsonData = response.body().string();
JSONObject invoicesJsonObject = new JSONObject(invoicesJsonData);
JSONObject invoicesJsonObject1 = invoicesJsonObject.getJSONObject("_embedded");
JSONArray f2=invoicesJsonObject1.getJSONArray("invoices");
for(int i=0;i<f2.length();i++){
JSONObject obj=f2.getJSONObject(i);
if(obj.get("batchPublicId")!=null){
System.out.println(obj.get("batchPublicId"));
}
You can do something like this,Which worked out for me sometimes back.
String invoicesJsonData = response.body().string();
JSONObject invoicesJsonObject = new JSONObject(invoicesJsonData);
JSONObject invoicesJsonObject = json.getJSONObject("invoicesJsonObject");
String batchPublicId = invoicesJsonObject.getString("batchPublicId");
System.out.println( "batchPublicId: " + batchPublicId );
if(batchPublicId !=null){
// do something
}
Not sure about the syntax.Giving you a hint.
you can check any keys is there in json object or not like below :
if(jsonObject1.has("batchPublicId")){
String batchPublicId = jsonObject1.optString("batchPublicId");
Log.i(getClass().getSimpleName(), "batchPublicId=" + batchPublicId);}
has method is used to find any key is there in jsonobject or not.
In my opinion, a better approach for this would be to create a POJO from this JSON string, and extract the information you need using simply the getters
For example:
Wrapper class:
#JsonIgnoreProperties(ignoreUnknown = true)
#JsonRootName(value = "_embedded")
public class Embeded {
#JsonProperty("invoices")
private List<Invoice> invoices;
public Embeded() {}
public List<Invoice> getInvoices() {
return invoices;
}
public void setInvoices(List<Invoice> invoices) {
this.invoices = invoices;
}
}
Invoice class:
#JsonIgnoreProperties(ignoreUnknown = true)
public class Invoice {
#JsonProperty("type")
private String type;
#JsonProperty("publicId")
private String publicId;
#JsonProperty("deliveryStatus")
private String deliveryStatus;
#JsonProperty("processingStatus")
private String processingStatus;
#JsonProperty("batchPublicId")
private String batchPublicId;
public Invoice() {}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getPublicId() {
return publicId;
}
public void setPublicId(String publicId) {
this.publicId = publicId;
}
public String getDeliveryStatus() {
return deliveryStatus;
}
public void setDeliveryStatus(String deliveryStatus) {
this.deliveryStatus = deliveryStatus;
}
public String getProcessingStatus() {
return processingStatus;
}
public void setProcessingStatus(String processingStatus) {
this.processingStatus = processingStatus;
}
public String getBatchPublicId() {
return batchPublicId;
}
public void setBatchPublicId(String batchPublicId) {
this.batchPublicId = batchPublicId;
}
}
Test:
public void json_test() throws JsonParseException, JsonMappingException, IOException {
String json = "{"
+ "\"_embedded\": {"
+ "\"invoices\": ["
+ "{"
+ "\"type\": \"INVOICE\","
+ "\"publicId\": \"27bc8426-17cf-4fe5-9278-64108ae05e4b\","
+ "\"deliveryStatus\": null,"
+ "\"processingStatus\": \"INITIATED\","
+ "\"batchPublicId\": \"0000000000000000000000001\""
+ "}"
+ "]"
+ "}"
+ "}";
ObjectMapper mapper = new ObjectMapper();
mapper.configure(Feature.UNWRAP_ROOT_VALUE, true);
List<Invoice> invoices = mapper.readValue(json, Embeded.class).getInvoices();
Assert.assertTrue(StringUtils.equals(invoices.get(0).getBatchPublicId(), "0000000000000000000000001"));
}
If I understand your right, you just need to call:
Assert.assertTrue(invoicesJsonObject.getString("batchPublicId").equals("0000000000000000000000001"));"
If you want to create a test for JSON Validation, you can use the JSONAssert.
JSONAsset give the method assertEquals, that compare two json structures, strict identic or not.
final String expected_result = YOUR_EXPECTED_RESULT;
JSONAssert.assertEquals(YOUR_EXPECTED_JSON_RESULT, RESULT_FROM_RESPONSE_BODY, false);
The last boolean parameter defines if you want an strict comparation or just compare if your expected result is in result from response.

Json to pojo convertions

How we convert following type of json into java object
{
"complaint_Map": {
"1000067730": "3011351597604397",
"1000067730-06": "10582576134561065"
}
}
if anyone have any idea about this tell how we do that.
With jackson
import com.fasterxml.jackson.databind.ObjectMapper;
Try
ObjectMapper mapper = new ObjectMapper();
String jsonInString = "{\"complaint_Map\":{\"1000067730\":\"3011351597604397\",\"1000067730-06\":\"10582576134561065\"}}";
Map<String,Object> pojo = mapper.readValue(jsonInString, Map.class);
System.out.println(((Map<String,Object>)pojo.get("complaint_Map")).get("1000067730")+"");
will print
3011351597604397
In java you can use Jackson library that converts a simple POJO to/from JSON.
From Wikipedia:
Jackson is a high-performance JSON processor for Java. Developers of it extol the combination of fast, correct, lightweight, and ergonomic attributes of the library.
Here an example taken by Wikipedia:
public class ReadWriteJackson {
public static void main(String[] args) throws IOException {
ObjectMapper mapper = new ObjectMapper();
String jsonInput =
"{\"id\":0,\"firstName\":\"Robin\",\"lastName\":\"Wilson\"}";
Person q = mapper.readValue(jsonInput, Person.class);
System.out.println("Read and parsed Person from JSON: " + q);
Person p = new Person("Roger", "Rabbit");
System.out.print("Person object " + p + " as JSON = ");
mapper.writeValue(System.out, p);
}
}
You can do it with ObjectMapper from jackson.
Suppose the json is defines a java object,
then it can be done by
import org.codehaus.jackson.map.ObjectMapper;
YourObject mappingClassObject = new YourObject();
ObjectMapper mapper = new ObjectMapper();
try{
mappingClassObject = mapper.readValue(yourJSON, YourObject.class);
}catch(Exception e){
e.printStackTrace();
}
If you want a solution using Jackson library, here it is.
The custom class:
#JsonRootName("complaint_Map")
public class Complaint {
private String firstKey;
private String secondKey;
#JsonProperty("1000067730")
public String getFirstKey() {
return firstKey;
}
#JsonProperty("1000067730")
public void setFirstKey(String firstKey) {
this.firstKey = firstKey;
}
#JsonProperty("1000067730-06")
public String getSecondKey() {
return secondKey;
}
#JsonProperty("1000067730-06")
public void setSecondKey(String secondKey) {
this.secondKey = secondKey;
}
#Override
public String toString() {
return "Complaint{" +
"firstKey='" + firstKey + '\'' +
", secondKey='" + secondKey + '\'' +
'}';
}
}
And the way of testing:
String jsonString = "{\"complaint_Map\":{\"1000067730\":\"3011351597604397\",\"1000067730-06\":\"10582576134561065\"}}";
ObjectMapper mapper = new ObjectMapper();
mapper.configure(DeserializationFeature.UNWRAP_ROOT_VALUE, true);
try {
Complaint complaint = mapper.readValue(jsonString, Complaint.class);
System.out.println(complaint);
} catch (Exception e) {
e.printStackTrace();
}
I used the following version (in Maven pom):
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.4.1.3</version>
</dependency>

Jersey - Json to java string

I am new to JSON web service. I want to convert below simple JSON structure to Java String. Though I have referred many sites, still it adds more confusion to me. I am using GSON for parsing but alwasy getting
"java.lang.IllegalStateException: This is not a JSON Array."
Please assist me to resolve the issue.
JSON DATA : {"data1":"100","data2":"hello"}
JAVA CODE :
private void getPostMessage(String msg) {
try {
EmployeeBean emp;
String json;
Client client = Client.create();
WebResource webResource = client.resource("http://localhost:8080/JSON_EMP_Serv/rest/server/post/");
ClientResponse response = webResource.type("application/json").post(ClientResponse.class,msg);
if (response.getStatus() != 201) {
throw new RuntimeException("Failed : HTTP error code : " + response.getStatus());
}
String output = response.getEntity(String.class);
System.out.println("\n============get POST Message Response============");
System.out.println(output);
/******* JSON PARSER **********/
Gson gson = new Gson();
JsonParser parser = new JsonParser();
JsonArray Jarray = parser.parse(output).getAsJsonArray();
ArrayList<EmployeeBean> lcs = new ArrayList<EmployeeBean>();
for(JsonElement obj : Jarray )
{
emp = gson.fromJson(obj,EmployeeBean.class);
lcs.add(emp);
}
int length=lcs.size();
System.out.println("ARRAY LENGTH"+length);
for(int i=0;i<length;i++)
{
System.out.println(lcs.get(i)+"\n");
}
} catch (Exception e) {
e.printStackTrace();
}
}
EMPLOYEEBEAN CLASS :
package com.pats.client.bean;
import java.util.ArrayList;
import java.util.List;
import com.google.gson.annotations.SerializedName;
public class EmployeeBean {
private String data1= null;
private String data2 = null;
public EmployeeBean(String data1,String data2)
{
this.data1=data1;
this.data2=data2;
}
public String getData1()
{ return data1; }
public String getData2()
{ return data2; }
public void setData1(String data1)
{
this.data1=data1;
}
public void setData2(String data2)
{
this.data2=data2;
}
#Override
public String toString() {
//return "[data1=" + data1 + ", data2=" + data2 + "]";
return " DATA-1 : " + this.data1 + "DATA-2 : " + this.data2;
}
}
The point is, clearly, that your data is not a JSON array.
{"data1":"100","data2":"hello"}
It is, instead, a JSON object, but you are trying to parse it and get a JsonArray. You could change this and use getAsJsonObject() instead, but from your code I think it's your starting data that is wrong. I guess you should have an array of employees, so the correct data should probably be something like:
[{"data1":"100","data2":"hello"}]

How to convert list data into json in java

I have a function which is returning Data as List in java class. Now as per my need, I have to convert it into Json Format.
Below is my function code snippet:
public static List<Product> getCartList() {
List<Product> cartList = new Vector<Product>(cartMap.keySet().size());
for(Product p : cartMap.keySet()) {
cartList.add(p);
}
return cartList;
}
I tried To convert into json by using this code but it is giving type mismatch error as function is of type List...
public static List<Product> getCartList() {
List<Product> cartList = new Vector<Product>(cartMap.keySet().size());
for(Product p : cartMap.keySet()) {
cartList.add(p);
}
Gson gson = new Gson();
// convert your list to json
String jsonCartList = gson.toJson(cartList);
// print your generated json
System.out.println("jsonCartList: " + jsonCartList);
return jsonCartList;
}
Please help me resolve this.
Using gson it is much simpler. Use following code snippet:
// create a new Gson instance
Gson gson = new Gson();
// convert your list to json
String jsonCartList = gson.toJson(cartList);
// print your generated json
System.out.println("jsonCartList: " + jsonCartList);
Converting back from JSON string to your Java object
// Converts JSON string into a List of Product object
Type type = new TypeToken<List<Product>>(){}.getType();
List<Product> prodList = gson.fromJson(jsonCartList, type);
// print your List<Product>
System.out.println("prodList: " + prodList);
public static List<Product> getCartList() {
JSONObject responseDetailsJson = new JSONObject();
JSONArray jsonArray = new JSONArray();
List<Product> cartList = new Vector<Product>(cartMap.keySet().size());
for(Product p : cartMap.keySet()) {
cartList.add(p);
JSONObject formDetailsJson = new JSONObject();
formDetailsJson.put("id", "1");
formDetailsJson.put("name", "name1");
jsonArray.add(formDetailsJson);
}
responseDetailsJson.put("forms", jsonArray);//Here you can see the data in json format
return cartList;
}
you can get the data in the following form
{
"forms": [
{ "id": "1", "name": "name1" },
{ "id": "2", "name": "name2" }
]
}
Try these simple steps:
ObjectMapper mapper = new ObjectMapper();
String newJsonData = mapper.writeValueAsString(cartList);
return newJsonData;
ObjectMapper() is com.fasterxml.jackson.databind.ObjectMapper.ObjectMapper();
i wrote my own function to return list of object for populate combo box :
public static String getJSONList(java.util.List<Object> list,String kelas,String name, String label) {
try {
Object[] args={};
Class cl = Class.forName(kelas);
Method getName = cl.getMethod(name, null);
Method getLabel = cl.getMethod(label, null);
String json="[";
for (int i = 0; i < list.size(); i++) {
Object o = list.get(i);
if(i>0){
json+=",";
}
json+="{\"label\":\""+getLabel.invoke(o,args)+"\",\"name\":\""+getName.invoke(o,args)+"\"}";
//System.out.println("Object = " + i+" -> "+o.getNumber());
}
json+="]";
return json;
} catch (ClassNotFoundException ex) {
Logger.getLogger(JSONHelper.class.getName()).log(Level.SEVERE, null, ex);
} catch (Exception ex) {
System.out.println("Error in get JSON List");
ex.printStackTrace();
}
return "";
}
and call it from anywhere like :
String toreturn=JSONHelper.getJSONList(list, "com.bean.Contact", "getContactID", "getNumber");
Try like below with Gson Library.
Earlier Conversion List format were:
[Product [Id=1, City=Bengalore, Category=TV, Brand=Samsung, Name=Samsung LED, Type=LED, Size=32 inches, Price=33500.5, Stock=17.0], Product [Id=2, City=Bengalore, Category=TV, Brand=Samsung, Name=Samsung LED, Type=LED, Size=42 inches, Price=41850.0, Stock=9.0]]
and here the conversion source begins.
//** Note I have created the method toString() in Product class.
//Creating and initializing a java.util.List of Product objects
List<Product> productList = (List<Product>)productRepository.findAll();
//Creating a blank List of Gson library JsonObject
List<JsonObject> entities = new ArrayList<JsonObject>();
//Simply printing productList size
System.out.println("Size of productList is : " + productList.size());
//Creating a Iterator for productList
Iterator<Product> iterator = productList.iterator();
//Run while loop till Product Object exists.
while(iterator.hasNext()){
//Creating a fresh Gson Object
Gson gs = new Gson();
//Converting our Product Object to JsonElement
//Object by passing the Product Object String value (iterator.next())
JsonElement element = gs.fromJson (gs.toJson(iterator.next()), JsonElement.class);
//Creating JsonObject from JsonElement
JsonObject jsonObject = element.getAsJsonObject();
//Collecting the JsonObject to List
entities.add(jsonObject);
}
//Do what you want to do with Array of JsonObject
System.out.println(entities);
Converted Json Result is :
[{"Id":1,"City":"Bengalore","Category":"TV","Brand":"Samsung","Name":"Samsung LED","Type":"LED","Size":"32 inches","Price":33500.5,"Stock":17.0}, {"Id":2,"City":"Bengalore","Category":"TV","Brand":"Samsung","Name":"Samsung LED","Type":"LED","Size":"42 inches","Price":41850.0,"Stock":9.0}]
Hope this would help many guys!
JSONObject responseDetailsJson = new JSONObject();
JSONArray jsonArray = new JSONArray();
List<String> ls =new ArrayList<String>();
for(product cj:cities.getList()) {
ls.add(cj);
JSONObject formDetailsJson = new JSONObject();
formDetailsJson.put("id", cj.id);
formDetailsJson.put("name", cj.name);
jsonArray.put(formDetailsJson);
}
responseDetailsJson.put("Cities", jsonArray);
return responseDetailsJson;
You can use the following method which uses Jackson library
public static <T> List<T> convertToList(String jsonString, Class<T> target) {
if(StringUtils.isEmpty(jsonString)) return List.of();
return new ObjectMapper().readValue(jsonString, new ObjectMapper().getTypeFactory().
constructCollectionType(List.class, target));
} catch ( JsonProcessingException | JSONException e) {
e.printStackTrace();
return List.of();
}
}
if response is of type List , res.toString() is simply enough to convert to json or else we need to use
ObjectMapper mapper = new ObjectMapper();
String jsonRes = mapper.writeValueAsString(res);

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