How to get values from JSONObject in Java? - java

I am trying to parse a JsonArray and get its values but I am gettign error when I use
jitem.getString("firstitem");
or
jitem.getJSONObject("firstitem");
or
jitem.get("firstitem");
Following is the code snippet.
JSONArray arr_items = new JSONArray(str);
if(arr_items!=null && arr_items.size()>0){
for(int i=0;i<arr_items.size();i++){
JSONObject jitem = arr_items.getJSONObject(i);//works fine till here
jitem.getString("firstitem"); //throws exception here
}
This is the JSONArray that I am parsing
[{"firstitem":"dgfd","secondtitem":"dfgfdgfdg","thirditem":"fdgfdgdf#sjhasjkdsha.com","fourthitem":"jkksdjklsfjskj"}]
what I am doing wrong? How to get these values by using keys?
Update:Note This array and its parameters are not null at all. They all have valid values.


First check arr_items is not empty.
Then, try surrounding your snippet with try/catch :
try {
your snippet
} catch (JSONException e) {
e.printStackTrace();
}


Check below
String json ="{'array':" + "[{'firstitem':'dgfd','secondtitem':'dfgfdgfdg','thirditem':'fdgfdgdf#sjhasjkdsha.com','fourthitem':'jkksdjklsfjskj'}]"+ "}";
JSONObject myjson = new JSONObject(json);
JSONArray the_json_array = myjson.getJSONArray("array");
int size = the_json_array.length();
// ArrayList<JSONObject> arrays = new ArrayList<JSONObject>();
for (int i = 0; i < size; i++) {
JSONObject another_json_object = the_json_array.getJSONObject(i);
// arrays.add(another_json_object);
System.out.println(another_json_object.get("firstitem"));
}
it require some array name so appended array name to it , if you want without it you have to add GSON.

Related

Convert Json String to List in Android

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

Count number of Strings and JSONObjects in JSONArray

I am trying to parse a JSON schema and I need to get all the image links from the JSONArray and store it in a java array. The JSONArray looks like this:
How can I get only the number of strings in the image array for e.g. In this case it should be 4? I know how to get the full length of array but how can I only get the number of strings?
UPDATE:
I am simply parsing it using the standard JSON parser for android. The length of JSONArray can be calculated using:
JSONArray imageArray = hist.getJSONArray("image");
int len = imageArray.length();
len will be equal to 9 in this case.

I'm not sure if there's a better way (there probably is), but here's one option:
According to the Android docs, getJSONObject will throw a JSONException if the element at the specified index is not a JSON object. So, you can try to get the element at each index using getJSONObject. If it throws a JSONException, then you know it's not a JSON object. You can then try and get the element using getString. Here's a crude example:
JSONArray imageArray = hist.getJSONArray("image");
int len = imageArray.length();
ArrayList<String> imageLinks = new ArrayList<String>();
for (int i = 0; i < len; i++) {
boolean isObject = false;
try {
JSONArray obj = imageArray.getJSONObject(i);
// obj is a JSON object
isObject = true;
} catch (JSONException ex) {
// ignore
}
if (!isObject ) {
// Element at index i was not a JSON object, might be a String
try {
String strVal = imageArray.getString(i);
imageLinks.add(strVal);
} catch (JSONException ex) {
// ignore
}
}
}
int numImageLinks = imageLinks.size();

Java - looping through JSONArray

i am trying to call an URL and afterwards to save the results of the URL into a database.
The call of the URL is working and i also am able to save the result into JSON objects/arrays.
This is my code so far:
JSONParser parser = new JSONParser();
try
{
// responseString is the answer i get from calling the URL.
// It's pretty long that's why i don't copy it in here now
// But you can call this URL to see what the result is:
// http://www.gw2spidy.com/api/v0.9/json/items/all/1?filter_ids=29169,29185
Object objToParse = parser.parse(responseString);
JSONObject jsonObject = (JSONObject) objToParse;
JSONArray array = (JSONArray) jsonObject.get("results");
// Until here everything is ok, the results get saved into the array
JSONObject mJsonObject = new JSONObject();
for (int i = 0; i < array.length() ; i++)
{
mJsonObject = (JSONObject)array.get(i);
System.out.println(mJsonObject);
}
}
catch(ParseException pe)
{
System.out.println("position: " + pe.getPosition());
System.out.println(pe);
}
When i try to run this i get an error when i try to loop through the array:
Exception in thread "main" java.lang.ClassCastException: org.json.simple.JSONArray cannot be cast to java.lang.CharSequence
I already searched for solutions but i cannot find or understand what is causing the error for me, would be nice if someone can help me here..

Ok at the end this was working for me:
JSONObject jsonObject = new JSONObject(responseString);
JSONArray array = (JSONArray) jsonObject.get("results");
JSONObject mJsonObject = new JSONObject();
for (int i = 0; i < array.length() ; i++)
{
mJsonObject = (JSONObject)array.get(i);
System.out.println(mJsonObject);
}
Had to change org.json.simple to instead use org.json and changed some lines then it was working.

I rather think that your implementation using simple json was wrong.
Although you didn't mention exactly, the only place your Exception could happen would be the line
JSONArray array = (JSONArray) jsonObject.get("results");
and as this is the same in both implementations, something previous to that must have happened leading to a situation with simple json where the results property is not a JSONArray. Probably something with parser.parse(...).

Convert returned JSON String to a JSONArray

I have a web service that performs a database query, converts the result set to a JSON String and returns the strung to the client. This is the code for the converter (I got it from http://biercoff.com/nice-and-simple-converter-of-java-resultset-into-jsonarray-or-xml/):
public static String convertToJSON(ResultSet resultSet)
throws Exception {
JSONArray jsonArray = new JSONArray();
while (resultSet.next()) {
int total_rows = resultSet.getMetaData().getColumnCount();
JSONObject obj = new JSONObject();
for (int i = 0; i < total_rows; i++) {
obj.put(resultSet.getMetaData().getColumnLabel(i + 1)
.toLowerCase(), resultSet.getObject(i + 1));
}
jsonArray.add(obj);
}
return jsonArray.toJSONString();
}
In the client application when I print the returned string it is in the following format:
[{"Column1":0.333333,"Column2":"FirmA"},{"Column1":0.666667,"Column2":"FirmB"}]
so far all is good. The problem I am having is converting the returned string into a JSON array. I tried this:
JSONArray arr = new JSONArray(JSON_STRING);
but got the following error message: constructor JSONArray in class JSONArray cannot be applied to given types. I tried to first convert in into a JSON object like so:
JSONObject obj = new JSONObject(JSON_STRING);
but got the following error: incompatible types: String cannot be converted to Map. What am I doing wrong? Thanks.

Apparently the problem was with the json library that I was using. Once I used the
import org.json.JSONArray;
it all worked out well. I was able to convert the returned string to an array using
JSONArray arr = new JSONArray(JSON_STRING);
and to iterate through the values I used the code provided in this answer: Accessing members of items in a JSONArray with Java which I reproduce here for simplicity:
for (int i = 0; i < arr.length(); ++i) {
JSONObject rec = arr.getJSONObject(i);
int id = rec.getInt("id");
String loc = rec.getString("loc");
// ...
}

well you need to do it by this way for example
String jsonText = "[0,{\"1\":{\"2\":{\"3\":{\"4\":[5,{\"6\":7}]}}}}]";
try {
JSONArray array = new JSONArray(jsonText);
System.out.println(array);
System.out.println(array.length());
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}

Check the correct library used. The mess is that org.json.simple is often suggested by IDE as default for JSONObject and JSONArray.
You can find a link to latest jar for org.json library above.

Reading JSON on Android, No Output

This is my JSON data.
{"JSONDATA":[{"key":0,"value":"--Any--"},{"key":61,"value":"Accounting"},{"key":81,"value":"Aerospace & Defense"},{"key":72,"value":"Automotive"},{"key":83,"value":"Banking"},{"key":84,"value":"Biotech"},{"key":85,"value":"Construction"},{"key":86,"value":"Customer Service"},{"key":87,"value":"Education"},{"key":82,"value":"Energy"},{"key":70,"value":"Finance"},{"key":193,"value":"Government"},{"key":194,"value":"Healthcare"},{"key":71,"value":"Insurance"},{"key":73,"value":"Legal"},{"key":62,"value":"Management"},{"key":63,"value":"Manufacturing"},{"key":64,"value":"Marketing\/Advertising"},{"key":77,"value":"Media - Journalism"},{"key":74,"value":"Pharmaceutical"},{"key":75,"value":"Real Estate"},{"key":76,"value":"Research"},{"key":65,"value":"Restaurant"},{"key":66,"value":"Retail"},{"key":67,"value":"Sales"},{"key":78,"value":"Science"},{"key":68,"value":"Telecommunications"},{"key":79,"value":"Training"},{"key":69,"value":"Transportation"},{"key":80,"value":"Utilities"}]}
I want to decode it on my Android App, This is the code i have used., But i don't get anything on my output. No errors too.
JSONObject jObject= new JSONObject();
JSONArray menuObject = new JSONArray(jObject.getString("JSONDATA"));
String app;
for (int i = 0; i<menuObject.length(); i++) {
{
app=menuObject.getJSONObject(i).getString("value").toString();
a.append(app); // a is my TextView
}

First off, you're not initializing your jObject with anything.
//pass in string
JSONObject jObject= new JSONObject(jsonString);
JSONObjects need something to parse, otherwise (the way you have it now) they initialize with no data, which isn't very helpful.
Secondly, you're using getString when you really want an array:
JSONArray menuObject = jObject.getJSONArray("JSONDATA");
getString is designed to return a piece of string data from a JSON object. "JSONDATA" holds an array, so we need to choose the correct type to retrieve.
Thirdly, you have a redundant toString(), as getString already returns a String:
app=menuObject.getJSONObject(i).getString("value");

Its wrong:
JSONArray menuObject = new JSONArray(jObject.getString("JSONDATA"));
Try:
JSONObject jObject= new JSONObject(yourJSONString);
JSONArray menuObject = jObject.getJSONArray("JSONDATA");
Keep one thing in mind:
Create a JSON Object with JSON String you want to parse and then you can fetch String/JSON Object or JSON Array from the created JSON Object.

Store your json response in a String
String jsonResponse="YOUR JSON RESPONSE STRING";
//Pass the string as below
JSONObject jObject= new JSONObject(jsonResponse);
JSONArray menuObject = jObject.getJSONArray("JSONDATA"));
String app;
for (int i = 0; i<menuObject.length(); i++) {
{
app=menuObject.getJSONObject(i).getString("value").toString();
a.append(app); // a is my TextView
}

Use the appropiate getters and setters in JSONObject and JSONArray, and your "JSONDATA" entry is not a string. Do something like this:
JSONObject jObject = new JSONObject(yourJsonString);
JSONArray menuArray = jObject.getJSONArray("JSONDATA");
for (int i = 0; i < menuArray.length(); i++) {
String app = menuObject.getJSONObject(i).getString("value");
a.append(app); // a is my TextView
}

Use following code for parse your json string.
JSONObject obj = new JSONObject(youtString);
JSONArray array = obj.getJSONArray("JSONDATA");
for (int i = 0; i < array.length(); i++) {
JSONObject c = array.getJSONObject(i);
String key = c.getString("key");
String value = c.getString("value");
a.append(value);
}

Use this:-
String result="[{"key":0,"value":"--Any--"},{"key":61,"value":"Accounting"},{"key":81,"value":"Aerospace & Defense"},{"key":72,"value":"Automotive"},{"key":83,"value":"Banking"},{"key":84,"value":"Biotech"},{"key":85,"value":"Construction"},{"key":86,"value":"Customer Service"},{"key":87,"value":"Education"},{"key":82,"value":"Energy"},{"key":70,"value":"Finance"},{"key":193,"value":"Government"},{"key":194,"value":"Healthcare"},{"key":71,"value":"Insurance"},{"key":73,"value":"Legal"},{"key":62,"value":"Management"},{"key":63,"value":"Manufacturing"},{"key":64,"value":"Marketing\/Advertising"},{"key":77,"value":"Media - Journalism"},{"key":74,"value":"Pharmaceutical"},{"key":75,"value":"Real Estate"},{"key":76,"value":"Research"},{"key":65,"value":"Restaurant"},{"key":66,"value":"Retail"},{"key":67,"value":"Sales"},{"key":78,"value":"Science"},{"key":68,"value":"Telecommunications"},{"key":79,"value":"Training"},{"key":69,"value":"Transportation"},{"key":80,"value":"Utilities"}]";
JSONArray menuObject = new JSONArray(result);
String app;
for (int i = 0; i<menuObject.length(); i++) {
{
app=menuObject.getJSONObject(i).getString("value").toString();
a.append(app); // a is my TextView
}

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