All type of json elements like objects in json files arrays and simple key value pairs.
When you call JSONParser parser = new JSONParser(); obj = parser.parse(path);
parser.parse() expects an actual JSON string, not the path to the JSON file.
It wants to see something like this:
json.parse("{ "name":"John", "age":31, "city":"New York" }");
To fix your code, you can do this:
List < String > list = new ArrayList < >();
try (BufferedReader br = Files.newBufferedReader(Paths.get(path))) {
//br returns as stream and convert it into a List
list = br.lines().collect(Collectors.toList());
} catch(IOException e) {
e.printStackTrace();
}
StringBuilder sb = new StringBuilder();
for (String s: list) {
sb.append(s);
}
String json = sb.toString()
JSONParser parser = new JSONParser();
obj = parser.parse(json);
Related
strResponse = {"GetCitiesResult":["1-Vizag","2-Hyderbad","3-Pune","4-Chennai","9-123","11-Rohatash","12-gopi","13-Rohatash","14-Rohatash","10-123"]}
JSONObject json = new JSONObject(strResponse);
// get LL json object
String json_LL = json.getJSONObject("GetCitiesResult").toString();
Now i want to convert the json string to List in andriod
Please make sure your response String is correct format, if it is, then try this:
try {
ArrayList<String> list = new ArrayList<String>();
JSONObject json = new JSONObject(strResponse);
JSONArray array = json.getJSONArray("GetCitiesResult");
for (int i = 0; i < array.length(); i++) {
list.add(array.getString(i));
}
} catch (Exception e) {
e.printStackTrace();
}
Simply using Gson library you can convert json response to pojo class.
Copy the json string to create pojo structure using this link: http://www.jsonschema2pojo.org/
Gson gson = new Gson();
GetCitiesResult citiesResult = gson.fromJson(responseString, GetCitiesResult.class);
It will give the GetCitiesResult object inside that object you get a list of your response like
public List<String> getGetCitiesResult() {
return getCitiesResult;
}
Call only citiesResult.getGetCitiesResult(); it will give a list of cities.
You can also use this library com.squareup.retrofit2:converter-gson:2.1.0
This piece of code did the trick
List<String> list3 = json.getJSONArray("GetCitiesResult").toList()
.stream()
.map(o -> (String) o)
.collect(Collectors.toList());
list3.forEach(System.out::println);
And printed:
1-Vizag
2-Hyderbad
3-Pune
4-Chennai
9-123
11-Rohatash
12-gopi
13-Rohatash
14-Rohatash
10-123
below is code:
private void parse(String response) {
try {
List<String> stringList = new ArrayList<>();
JSONObject jsonObject = new JSONObject(response);
JSONArray jsonArray = jsonObject.getJSONArray("GetCitiesResult");
for (int i=0; i <jsonArray.length(); i++){
stringList.add(jsonArray.getString(i));
}
Log.d ("asd", "--------"+ stringList);
} catch (Exception e) {
e.printStackTrace();
}
}
Hope it will help.
Output is when print list :
--------[1-Vizag, 2-Hyderbad, 3-Pune, 4-Chennai, 9-123, 11-Rohatash, 12-gopi, 13-Rohatash, 14-Rohatash, 10-123]
Ok you must know first something about JSON
Json object is be {// some attribute}
Json Array is be [// some attribute]
Now You have
{"GetCitiesResult":["1-Vizag","2-Hyderbad",
"3-Pune","4-Chennai","9-123","11-Rohatash",
"12-gopi","13-Rohatash","14-Rohatash","10-123"]}
That`s Means you have JSON array is GetCitiesResult
which have array of String
Now Try this
JSONObject obj = new JSONObject(data);
JSONArray loadeddata = new JSONArray(obj.getString("GetCitiesResult"));
for (int i = 0; i <DoctorData.length(); i++) {// what to do here}
where data is your String
I am trying to convert json file into csv file and I am using following code for that
public File convert(File toConvert) {
// TODO Auto-generated method stub
String JsonString = "{\"value\": [{\"name\",\"kind\":\"url\":]}";
JSONParser file = new JSONParser();
Object obj = file;
JSONObject jsonfile = (JSONObject) obj; //JSONObject from map interface
String name = (String) jsonfile.get("name");
System.out.println(name);
String kind = (String) jsonfile.get("kind");
System.out.println(kind);
JSONArray url = (JSONArray) jsonfile.get("url"); //JSONArray from list interface
Iterator<String> iterator = url.iterator();
while (iterator.hasNext()) {
System.out.println(iterator.next());
}
return toConvert ;
}
and my json file has a huge data and it looks like this
{
"value":[
{
"name":"accountleadscollection","kind":"EntitySet","url":"accountleadscollection"
},{
"name":"accounts","kind":"EntitySet","url":"accounts"
},{
"name":"activitymimeattachments","kind":"EntitySet","url":"activitymimeattachments"
},{
"name":"activityparties","kind":"EntitySet","url":"activityparties"
},{
"name":"activitypointers","kind":"EntitySet","url":"activitypointers"
},{
"name":"annotations","kind":"EntitySet","url":"annotations"
},{
"name":"annualfiscalcalendars","kind":"EntitySet","url":"annualfiscalcalendars"
},{...............
whenever I am trying to execute the code i am getting this error,Exception in thread "main" java.lang.ClassCastException. Is the logic I am following is correct or can anyone provide a better code for that, and I am implementing an interface which is having this method.
Convert the String in JSONObject.
Get the Array in the JSONObject by using the method getJSONArray("arraName").
If the array consist of Object then Iterate the array and then get the object using the index using method getJSONObject(index).
Now get the value using the key.
Here is the sample code in which you can do this.
Parse JSON from the string:
public void convert() throws JSONException {
String jsonString = readFile("prop.json"); //URL of your json file
JSONObject jsonObj = new JSONObject(jsonString);
JSONArray jsonArr = jsonObj.getJSONArray("value");
for (int j = 0; j < jsonArr.length(); j++) {
JSONObject tempJsonObj = jsonArr.getJSONObject(j);
System.out.println(tempJsonObj.get("name"));
System.out.println(tempJsonObj.get("kind"));
System.out.println(tempJsonObj.get("url"));
}
}
Read JSON file:
public String readFile(String filename) {
String result = "";
try {
BufferedReader br = new BufferedReader(new FileReader(filename));
StringBuilder sb = new StringBuilder();
String line = br.readLine();
while (line != null) {
sb.append(line);
line = br.readLine();
}
result = sb.toString();
} catch (Exception e) {
e.printStackTrace();
}
return result;
}
I have a json file formatted as the following:
[{
'title': 'Java',
'authors': ['Auth', 'Name']
},
{
'title': 'Java2',
'authors': ['Auth2', 'Name2']
},
{
'title': 'Java3',
'authors': ['Auth3', 'Name3']
}]
So i've tried using gson library to parse the file, with the following code:
JsonElement jelement = new JsonParser().parse(pathFile);
JsonObject jObject = jelement.getAsJsonObject();
JsonArray jOb = jObject.getAsJsonArray("");
final String[] jObTE = new String[jOb.size()];
for (int k=0; k<jObTE.length; k++) {
final JsonElement jCT = jOb.get(k);
JsonObject jOTE = jCT.getAsJsonObject();
JsonArray jContentTime = jOTE.getAsJsonArray("content_time");
final String[] contentTime = new String[jContentTime.size()];
for (int i=0; i<contentTime.length; i++) {
final JsonElement jsonCT = jContentTime.get(i);
JsonObject jObjectTE = jsonCT.getAsJsonObject();
JsonArray jTE = jObjectTE.getAsJsonArray("");
final String[] contentTimeTE = new String[jTE.size()];
for (int j=0; j<contentTimeTE.length; j++) {
final JsonElement jsonCTTE = jTE.get(j);
contentTime[j] = jsonCTTE.getAsString();
}
}
}
But, in doing so, i found this error: java.lang.IllegalStateException: Not a JSON Object at the second line.
You're trying to parse array to object, in which case you'll fail, because top level structure in your json is array.
I would parse this JSON in slightly different way
1) Create some Model class
public class Model {
private String title;
private List<String> authors;
//getters ...
}
2) Parse your JSON (
public static final String JSON_PATH = "/Users/dawid/Workspace/Test/test.json";
Gson gson = new Gson();
BufferedReader br = new BufferedReader(new FileReader(JSON_PATH));
Type type = new TypeToken<List<Model>>(){}.getType();
List<Model> models = gson.fromJson(br, type);
Your code is barely readable, so i guess that solved your problem
Second way:
BufferedReader br = new BufferedReader(new FileReader(JSON_PATH));
JsonParser parser = new JsonParser();
JsonArray array = parser.parse(br).getAsJsonArray();
I have JSON file, that I need to read, edit and write out again.
Reading works fine, I struggle with the write part of the JSON Array in my data.
I use JSON.simple library to work with JSON in Java.
The file looks like this:
{
"maxUsers":100,
"maxTextLength":2000,
"maxFileSize":2000,
"services":
[
{
"serviceName":"Яндекc",
"className":"YandexConnector.class",
"isEnabled":true
},
{
"serviceName":"Google",
"className":"GoogleConnector.class",
"isEnabled":false
}
]
}
When I try to write JSON-data (variable obj) to file, the services array is broken. My writing code:
JSONObject obj = new JSONObject();
obj.put("maxUsers", this.getMaxUsers());
obj.put("maxTextLength", this.getMaxTextLength());
obj.put("maxFileSize", this.getMaxFileSize());
JSONArray servicesJSON = new JSONArray();
ArrayList<Service> servicesArray = this.getServices();
for(int i=0; i< servicesArray.size(); i++)
{
servicesJSON.add(servicesArray.get(i));
}
obj.put("services", servicesJSON);
FileWriter file = new FileWriter(filename);
obj.writeJSONString(file);
file.flush();
file.close();
This outputs:
{
"services":
[
translator.settings.Service#121c5df,
translator.settings.Service#45f4ae
],
"maxTextLength":2000,
"maxUsers":100,
"maxFileSize":2000
}
How can I write the JSON data correctly to a file, if I have it in a JSONArray like services ?
The code, where I read the JSON data from the file (that works fine):
JSONParser parser = new JSONParser();
Object obj = parser.parse(new FileReader(filename));
JSONObject jsonObject = (JSONObject) obj;
setMaxUsers((Long) jsonObject.get("maxUsers"));
setMaxTextLength((Long) jsonObject.get("maxTextLength"));
setMaxFileSize((Long) jsonObject.get("maxFileSize"));
// get all list of services
JSONArray serv = (JSONArray) jsonObject.get("services");
for (int i = 0; i < serv.size(); i++) {
JSONObject service = (JSONObject) serv.get(i);
Service servec = new Service();
servec.setServiceName((String) service.get("serviceName"));
servec.setClassName((String) service.get("className"));
servec.setIsEnabled((Boolean) service.get("isEnabled"));
services.add(i, servec);
}
The editing part is not yet written, so I call the writing part directly after the reading.
Have a look at the examples of JSON-simple.
It says here that you need to put the Objects one by one into the Array, using only primitive and String values. You may use Collections like Map that by themselves only contain String or primitive values.
JSONArray list = new JSONArray();
list.add("foo");
list.add(new Integer(100));
list.add(new Double(1000.21));
list.add(new Boolean(true));
list.add(null);
StringWriter out = new StringWriter();
list.writeJSONString(out);
So, adding your Services is not allowed and won't work. You should add a toMap method in it where you convert it to a Map and fromMap to convert it back.
Like this (in Services.java):
public Map toMap() {
HashMap<String, String> serviceAsMap = new HashMap<>();
servicesAsMap.put("serviceName", serviceName);
servicesAsMap.put("className", this.class.getName() + ".class");
servicesAsMap.put("isEnabled", isEnabled);
// ... continue for all values
return servicesAsMap;
}
then you can use that Map to populate your JSONArray like this:
JSONArray servicesJSON = new JSONArray();
ArrayList<Service> servicesArray = this.getServices();
for(int i=0; i< servicesArray.size(); i++)
{
servicesJSON.add(servicesArray.get(i).toMap()); // use the toMap method here.
}
obj.put("services", servicesJSON);
Have a look at JSONArray Documentation.Here you will get list of methods available.This JSONArray is inherited from java.util.ArrayList,so we can use the methods available for ArrayList to JSONArray.
JSONArray userList = JSONFile.readJSONArray("users.json");
JSONArray newuserList = new JSONArray() ;
JSONObject jsonobject , newjsonObject;
for (int i = 0; i < userList.size(); i++) {
jsonobject = (JSONObject) userList.get(i);
String id = (String) jsonObject.get("id");
String pass = (String) jsonObject.get("password");
newuserList.add(jsonObject);
// Here we are putting json object into newuserList which is of JSONArray type
try{
FileWriter file = new FileWriter( "/users.json",false);
newuserList.writeJSONString(newuserList, file);
file.close();
}
catch(Exception e ){
e.getMessage();
}
Hope this will help !
I have a List<class> that I would like to convert into a json object and then traverse the data out of the json object.
If this were just a List<String> I could just do something like:
JSONObject obj = new JSONObject();
List<String> sList = new ArrayList<String>();
sList.add("val1");
sList.add("val2");
obj.put("list", sList);
Then I could traverse the list like:
JSONArray jArray = obj.getJSONArray("list");
for (int ii = 0; ii < jArray.size(); ii++)
System.out.println(jArray.getString(ii));
The problem with using the class is that I need to have access to data within each class element of my List<class> and I don't know how to encode that / traverse it into JSON. Any help would be greatly appreciated.
Call getJSONObject() instead of getString(). That will give you a handle on the JSON object in the array and then you can get the property off of the object from there.
For example, to get the property "value" from a List<SomeClass> where SomeClass has a String getValue() and setValue(String value):
JSONObject obj = new JSONObject();
List<SomeClass> sList = new ArrayList<SomeClass>();
SomeClass obj1 = new SomeClass();
obj1.setValue("val1");
sList.add(obj1);
SomeClass obj2 = new SomeClass();
obj2.setValue("val2");
sList.add(obj2);
obj.put("list", sList);
JSONArray jArray = obj.getJSONArray("list");
for(int ii=0; ii < jArray.length(); ii++)
System.out.println(jArray.getJSONObject(ii).getString("value"));
Let us assume that the class is Data with two objects name and dob which are both strings.
Initially, check if the list is empty. Then, add the objects from the list to a JSONArray
JSONArray allDataArray = new JSONArray();
List<Data> sList = new ArrayList<Data>();
//if List not empty
if (!sList.isEmpty()) {
//Loop index size()
for(int index = 0; index < sList.size(); index++) {
JSONObject eachData = new JSONObject();
try {
eachData.put("name", sList.get(index).getName());
eachData.put("dob", sList.get(index).getDob());
} catch (JSONException e) {
e.printStackTrace();
}
allDataArray.put(eachData);
}
} else {
//Do something when sList is empty
}
Finally, add the JSONArray to a JSONObject.
JSONObject root = new JSONObject();
try {
root.put("data", allDataArray);
} catch (JSONException e) {
e.printStackTrace();
}
You can further get this data as a String too.
String jsonString = root.toString();
This is how I do it using Google Gson. I am not sure, if there are a simpler way to do this (with or without an external library).
Type collectionType = new TypeToken<List<Class>>() {
}.getType();
String gsonString = new Gson().toJson(objList, collectionType);
You could use a JSON serializer/deserializer like flexjson to do the conversion for you.
Just to update this thread, here is how to add a list (as a json array) into JSONObject.
Plz substitute YourClass with your class name;
List<YourClass> list = new ArrayList<>();
JSONObject jsonObject = new JSONObject();
org.codehaus.jackson.map.ObjectMapper objectMapper = new
org.codehaus.jackson.map.ObjectMapper();
org.codehaus.jackson.JsonNode listNode = objectMapper.valueToTree(list);
org.json.JSONArray request = new org.json.JSONArray(listNode.toString());
jsonObject.put("list", request);