Once i have parsed a JSON String into a GSON provided JsonObject class, (assume that i do not wish to parse it into any meaningful data objects, but strictly want to use JsonObject), how am i able to modify a field / value of a key directly?
I don't see an API that may help me.
https://static.javadoc.io/com.google.code.gson/gson/2.6.2/com/google/gson/JsonObject.html
Strangely, the answer is to keep adding back the property. I was half expecting a setter method. :S
System.out.println("Before: " + obj.get("DebugLogId")); // original "02352"
obj.addProperty("DebugLogId", "YYY");
System.out.println("After: " + obj.get("DebugLogId")); // now "YYY"
This works for modifying childkey value using JSONObject.
import used is
import org.json.JSONObject;
ex json:(convert json file to string while giving as input)
{
"parentkey1": "name",
"parentkey2": {
"childkey": "test"
},
}
Code
JSONObject jObject = new JSONObject(String jsoninputfileasstring);
jObject.getJSONObject("parentkey2").put("childkey","data1");
System.out.println(jObject);
output:
{
"parentkey1": "name",
"parentkey2": {
"childkey": "data1"
},
}
Since 2.3 version of Gson library the JsonArray class have a 'set' method.
Here's an simple example:
JsonArray array = new JsonArray();
array.add(new JsonPrimitive("Red"));
array.add(new JsonPrimitive("Green"));
array.add(new JsonPrimitive("Blue"));
array.remove(2);
array.set(0, new JsonPrimitive("Yelow"));
Another approach would be to deserialize into a java.util.Map, and then just modify the Java Map as wanted. This separates the Java-side data handling from the data transport mechanism (JSON), which is how I prefer to organize my code: using JSON for data transport, not as a replacement data structure.
It's actually all in the documentation.
JSONObject and JSONArray can both be used to replace the standard data structure.
To implement a setter simply call a remove(String name) before a put(String name, Object value).
Here's an simple example:
public class BasicDB {
private JSONObject jData = new JSONObject;
public BasicDB(String username, String tagline) {
try {
jData.put("username", username);
jData.put("tagline" , tagline);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public String getUsername () {
String ret = null;
try {
ret = jData.getString("username");
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return ret;
}
public void setUsername (String username) {
try {
jData.remove("username");
jData.put("username" , username);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public String getTagline () {
String ret = null;
try {
ret = jData.getString("tagline");
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return ret;
}
public static JSONObject convertFileToJSON(String fileName, String username, List<String> list)
throws FileNotFoundException, IOException, org.json.simple.parser.ParseException {
JSONObject json = new JSONObject();
String jsonStr = new String(Files.readAllBytes(Paths.get(fileName)));
json = new JSONObject(jsonStr);
System.out.println(json);
JSONArray jsonArray = json.getJSONArray("users");
JSONArray finalJsonArray = new JSONArray();
/**
* Get User form setNewUser method
*/
//finalJsonArray.put(setNewUserPreference());
boolean has = true;
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject = jsonArray.getJSONObject(i);
finalJsonArray.put(jsonObject);
String username2 = jsonObject.getString("userName");
if (username2.equals(username)) {
has = true;
}
System.out.println("user name are :" + username2);
JSONObject jsonObject2 = jsonObject.getJSONObject("languages");
String eng = jsonObject2.getString("Eng");
String fin = jsonObject2.getString("Fin");
String ger = jsonObject2.getString("Ger");
jsonObject2.put("Eng", "ChangeEnglishValueCheckForLongValue");
System.out.println(" Eng : " + eng + " Fin " + fin + " ger : " + ger);
}
System.out.println("Final JSON Array \n" + json);
jsonArray.put(setNewUserPreference());
return json;
}
Related
I am trying to parse a json file in java. However I keep receiving an error.
This is the file I am trying to parse:
[{
"name": "John Smith",
"totalSales": 250,
"salesPeriod": 10,
"experienceMultiplier": 0.5
},
{
"name": "David Prowless",
"totalSales": 250,
"salesPeriod": 10,
"experienceMultiplier": 0.5
}
]
This is what I have tried:
public static void main(String[] args)
{
JSONParser parser = new JSONParser();
try {
Object obj = parser.parse(new FileReader("data.json"));
JSONObject jsonObject = (JSONObject) obj;
String name = (String) jsonObject.get("name");
System.out.println(name);
String totalSales = (String) jsonObject.get("totalSales");
System.out.println(totalSales);
String salesPeriod = (String) jsonObject.get("salesPeriod");
System.out.println(salesPeriod);
String exp = (String) jsonObject.get("exp");
System.out.println(exp);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ParseException e) {
e.printStackTrace();
}
}
This is the error I receive:
Exception in thread "main" java.lang.ClassCastException: org.json.simple.JSONArray cannot be cast to org.json.simple.JSONObject
at mentormate.json.MentormateJson.main(MentormateJson.java:23)
Java Result: 1
I apologize if this is a silly question with a simple solution. I am new to json.
EDIT:
I have decided to go along with the code below. However, I cannot set the for each loop right to iterate through object in the json file.
public static void main(String[] args) {
JSONParser parser = new JSONParser();
try {
Object obj = parser.parse(new FileReader("data.json"));
JSONArray jsonObjects = (JSONArray) obj;
for ( JSONObject jsonObject : jsonObjects) {
String name = (String) jsonObject.get("name");
System.out.println(name);
String totalSales = (String) jsonObject.get("totalSales");
System.out.println(totalSales);
String salesPeriod = (String) jsonObject.get("salesPeriod");
System.out.println(salesPeriod);
String exp = (String) jsonObject.get("exp");
System.out.println(exp);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ParseException e) {
e.printStackTrace();
}
}
FINAL EDIT (PROBLEM SOLVED):
public static void main(String[] args) {
JSONParser parser = new JSONParser();
try {
Object obj = parser.parse(new FileReader("data.json"));
JSONArray jsonObjects = (JSONArray) obj;
for (Object o : jsonObjects) {
JSONObject jsonObject = (JSONObject) o;
String name = (String) jsonObject.get("name");
System.out.println(name);
Long totalSales = (Long) jsonObject.get("totalSales");
System.out.println(totalSales);
Long salesPeriod = (Long) jsonObject.get("salesPeriod");
System.out.println(salesPeriod);
Double exp = (Double) jsonObject.get("experienceMultiplier");
System.out.println(exp);
System.out.println();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ParseException e) {
e.printStackTrace();
}
}
Please try this:
public static void main(String[] args) {
JSONParser parser = new JSONParser();
try {
Object obj = parser.parse(new FileReader("data.json"));
JSONArray jsonObjects = (JSONArray) obj;
for (Object o : jsonObjects) {
JSONObject jsonObject = (JSONObject) o;
String name = (String) jsonObject.get("name");
System.out.println(name);
Long totalSales = (Long)jsonObject.get("totalSales");
System.out.println(totalSales);
String salesPeriod = (String) jsonObject.get("salesPeriod");
System.out.println(salesPeriod);
String exp = (String) jsonObject.get("exp");
System.out.println(exp);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ParseException e) {
e.printStackTrace();
}
}
Your data contains a JSON array, not a JSON object.
Change the line
JSONObject jsonObject = (JSONObject) obj;
to
JSONArray jsonArray = (JSONArray) obj;
This array will contain two JSONObjects.
you can use alibaba's fastjson.You can download fastjson jar file,this is pom xml:
<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.56</version>
</dependency>
when you import this jar，you can code like this:
import com.alibaba.fastjson.JSONObject;
import java.util.List;
public class MainTest {
public static void main(String[] args) {
String json = "[\n" +
"{\n" +
"\"name\": \"John Smith\",\n" +
"\"totalSales\": 250,\n" +
"\"salesPeriod\": 10,\n" +
"\"experienceMultiplier\": 0.5\n" +
"},\n" +
"{\n" +
"\"name\": \"David Prowless\",\n" +
"\"totalSales\": 250,\n" +
"\"salesPeriod\": 10,\n" +
"\"experienceMultiplier\": 0.5\n" +
"}\n" +
"]";
List<JSONObject> jsonObjects = JSONObject.parseArray(json,JSONObject.class);
jsonObjects.stream().forEach(System.out::print);
}
}
Please find whole example below.
1) Create DTO class with your params like,
class JsonParam {
private String name;
private int totalSales;
private int salesPeriod;
private float experienceMultiplier;
//Getter and setters
}
2) Then add Gson jar with min. version (2.2.4) - get online, or add dependency for maven structure.
3) Finally, add 2 lines in your code to get any parameter like,
List<JsonParam> jsonParams = new Gson().fromJson(json, new TypeToken<List<JsonParam>>() {}.getType());
System.out.println(jsonParams.get(0).getName());
In above statement, I have used 0 index, you can use for-loop as per your requirement.
try {
JSONParser parser = new JSONParser();
try {
Object obj = parser.parse(new FileReader("./test.json"));
// parsing the JSON string inside the file that we created earlier.
JSONArray jsonarray = (JSONArray) obj;
for (int i = 0; i < jsonarray.size(); i++) {
JSONObject jsonObject = (JSONObject) jsonarray.get(i);
String name = (String) jsonObject.get("name");
System.out.println(name);
long totalSales = (long) jsonObject.get("totalSales");
System.out.println(totalSales);
long salesPeriod = (long) jsonObject.get("salesPeriod");
System.out.println(salesPeriod);
Double exp = (Double) jsonObject.get("experienceMultiplier");
System.out.println(exp);
}
} catch (Exception e) {
e.printStackTrace();
}
Try this one
I currently received the json file in java, turned the json file on the formun, debugged it, and tried sysout.
The problem is, I try to output to the table in jsp, but only the last source from json comes out.
How can we solve this?
#RequestMapping(value = "spaghettiSub", method = RequestMethod.POST)
public String spaghetti(ModelMap modelMap) {
JSONParser jsonParser = new JSONParser();
try{
JSONArray page = (JSONArray) jsonParser.parse(new FileReader("d:\\spaghetti.json"));
int pageCnt = page.size();
Map<String,String> map = new HashMap<String,String>();
List<Map<String,String>> spaghettiList = new ArrayList<Map<String,String>>();
for(int i = 0; i < pageCnt; i++) {
Object obj = page.get(i);
JSONObject jsonObject = (JSONObject) obj;
String no = (String) jsonObject.get("no");
String name = (String) jsonObject.get("name");
String explanation= (String) jsonObject.get("explanation");
map.put("no", no);
map.put("name", name);
map.put("explanation", explanation);
spaghettiList.add(map);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ParseException e) {
e.printStackTrace();
}
return "sub/" + this.urlbase + "/spaghetti";
}
json
[
{
"no": "1",
"name": "Spaghettoni",
"explanation": "It is commonly used in the Carbonara Spaghetti, which is about 2mm thick."
},
{
"no": "2",
"name": "Spaghettini",
"explanation": "Spaghetti 1.6mm thick"
},
{
"no": "3",
"name": "Fedelini",
"explanation": "Spaghetti from 1.3mm to 1.5mm thick"
}]
you have to move this Map<String,String> map = new HashMap<String,String>(); inside your for loop.
Note:
As JB Nizet mentioned start using objects instead of JsonArray.
First thing first
Solve Issue
You are only getting last row in your JSP is because you have declared your Map outside of for loop.
If you are in hurry and have no time in world just move this
Map<String,String> map = new HashMap<String,String>();
inside
for(int i = 0; i < pageCnt; i++) {
This will solve your problem.
Improve your Code
But you can make it way more better and efficient by doing something like this
Define a DTO class
public class MyData {
private String no;
private String name;
private String explanation;
// getter setter
}
Use this DTO class to fill values like you did for Map
The whole code looks something like this.
#RequestMapping(value = "spaghettiSub", method = RequestMethod.POST)
public String spaghetti(ModelMap modelMap) {
JSONParser jsonParser = new JSONParser();
try{
JSONArray page = (JSONArray) jsonParser.parse(new FileReader("d:\\spaghetti.json"));
int pageCnt = page.size();
List<MyData> spaghettiList = new ArrayList<MyData>();
for(int i = 0; i < pageCnt; i++) {
MyData mydata = new MyData();
Object obj = page.get(i);
JSONObject jsonObject = (JSONObject) obj;
String no = (String) jsonObject.get("no");
String name = (String) jsonObject.get("name");
String explanation= (String) jsonObject.get("explanation");
mydata.setNo(no);
mydata.setName(name);
mydata.setExplanation(explanation);
spaghettiList.add(mydata);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ParseException e) {
e.printStackTrace();
}
return "sub/" + this.urlbase + "/spaghetti";
}
I want to store the json array sent by php code in java array in android. My php code is working perfectly fine but in the app I get name: as the output. I want to display the names in the texview for checking purpose. Also I want to work with the namesby accessing them one by one.
Php code:
echo json_encode(array("result"=>$result));
Java code:
public class Salary {
public static final String DATA_URL1 = "http://********.com/name.php?salary=";
public static final String KEY_name = "name";
public static final String JSON_ARRAY1 = "result";
}
This is a method of my Name.java
private void showJSON(String response) {
String name = "";
try {
JSONObject jsonObject = new JSONObject(response);
JSONArray result = jsonObject.getJSONArray(Salary.JSON_ARRAY1);
for (int i = 0; i < result.length(); i++) {
JSONObject collegeData = result.getJSONObject(i);
name = collegeData.getString(Salary.KEY_name);
}
} catch (JSONException e) {
e.printStackTrace();
}
textViewResult1.setText("Name:\t" + name);
}
Use GSON Library
ArrayList<Salary> salaryArrayList = new ArrayList<>();
try {
salaryArrayList = new Gson().fromJson(response, new TypeToken<Salary>() {}.getType());
} catch (JsonSyntaxException e) {
e.printStackTrace();
}
Then use salaryArrayList to get values.
Download GSON jar from this link
I need to access to the "mid" but I need to sort it somehow, so I need to get the "code" and then get the "mid" value.
Can you help me with this, I have no idea how to refer to that.
Here is what I have:
public void onSuccess(String response) {
Log.i("CHACHING", "HTTP Sucess");
try {
JSONObject jsonObj = new JSONObject(response);
JSONObject ratesObject = jonObj.getJSONObject("rates");
String gbpcode = ratesObject.getString("code");
Double gbpRate = ratesObject.getDouble(gbpcode."mid");
Log.i("CHACHING", "GBP: " + gbpRate);
// Log.i("CHACHING", "EUR: " + eurRate);
Double usds = Double.valueOf(usdValue.getText().toString());
Double gbps = usds * gbpRate;
// Double euros = usds * eurRate;
gbpValue.setText("GBP: " + String.valueOf(gbps));
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
and the json looks like this
http://api.nbp.pl/api/exchangerates/tables/A/?format=json
The json received is list of json objects(json array) and in each json object "rates" is another json Array.
So, in order to access mid.
public void onSuccess(String response) { Log.i("CHACHING", "HTTP Sucess");
try {
JSONArray jsonArr = new JSONArray(response);
JSONObject jsonObj=jsonArr.getJSONObject(0);
//this jsonObj holds the first jsonObject of your response
JSONArray rateList = jonObj.getJSONArray("rates");
//rateList has the list of rates you obtained
//NOW, to get all mids for this rate list
for(int i=0;i<rateList.length();i++) {
JSONObject jO=rateList.getJSONObject(i);
Double mid=jO.getDouble("mid");
Double gbpcode = jO.getString("code");
/*
your code here
*/
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
i have a problem how to cast JSONObject or String to integer..
I send data once as a JSONObject
#GET
#Produces(MediaType.APPLICATION_JSON)
public JSONObject sayJSONHello() {
JSONArray numbers = new JSONArray();
numbers.put(1);
numbers.put(2);
numbers.put(3);
numbers.put(4);
JSONObject result = new JSONObject();
try {
result.put("numbers", numbers);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return result;
}
And one as a String
#Path("/test")
public class Hello {
#GET
#Produces(MediaType.APPLICATION_JSON)
public String sayJSONHello() {
String myString =null;
try
{
myString = new JSONObject().put("data", "1 2 4").toString();
}
catch (JSONException e)
{
e.printStackTrace();
}
return myString;
}
Then, i have problem how to receive this data as a Int.
I tried like this (Client):
Syste m.out.println(service.path("rest").path("hello").accept(MediaType.APPLICATION_JSON).get(String.class));
System.out.println(service.path("rest").path("test").accept(MediaType.APPLICATION_JSON).get(String.class));
String k = service.path("rest").path("test").accept(MediaType.APPLICATION_JSON).get(String.class);
// ERROR int temp = Integer.parseInt(k);
Could anyone advise how to deal with it ?
Your variable k is storing the whole JSON. You would need to parse the JSON object first and then pull out the specific integer (I assume in the array?) that you want.