This question already has answers here:
Get json array keys in android
(5 answers)
Closed 7 years ago.
I need to get a key name of JsonArray, so JSON looks like this, please not, that JSON is starting with array brackets, and inside it it has objects, that was made i guess because back end will have the ability to add objects.
[
{
"tehnology": [ ]
},
{
"science": []
}
]
So i need to get the names from it "technology" and "science", because json can dynamically change, how can I implement it?
The JSONArray contains JSONObjects. Retrieve every JSONObject and use keys() to access the key defined in every JSONObject
JSONArray jArray = new JSONArray(response);
for (int i = 0; i < jArray.length(); i++) {
JSONObject object = jArray.optJSONObject(i);
Iterator<String> iterator = object.keys();
while(iterator.hasNext()) {
String currentKey = iterator.next();
}
}
Related
Hi Below is a simple method which I am using to dynamically generate the JSON request based on Array length from some other API response.
However inside the for loop everything seems to work fine except at the end when JSONArray.add is called, it replaces old jsonObject values inside the array to a new one, and at the end whole array consists of the only same set of JSON objects.
After a lot of debugging can't find the solution, is due to a variable declaration or something. Below is the method I am using
For ref: I am using minidev.JSON
public JSONObject method1(JSONObject sampleJsonObjTemplate, String responseofotherapi) {
JSONArray jsonArray = JsonPath.parse(responseofotherapi).read("$.columns");
JSONArray dataSetColumnArray = new JSONArray();
JSONArray currentJsonColumnArr= JsonPath.parse(dataSetObj).read("$.columns");
JSONObject currentJsonColumnObject= (JSONObject) currentJsonColumnArr.get(0);
LinkedHashMap<String,Object> currentColumn;
for(int columnNumber = 0; columnNumber < jsonArray.size(); columnNumber++){
currentColumn= (LinkedHashMap<String,Object>)jsonArray.get(columnNumber);
String name = currentColumn.get("name").toString();
currentJsonColumnObject.put("name",name);
currentJsonColumnObject.put("alias",name+" Column Alias ");
currentJsonColumnObject.put("description",name+" Column Description ");
dataSetColumnArray.add(columnNumber,currentJsonColumnObject);
currentColumn.clear();
}
JSONObject updatedDataSetReq=JsonPath.parse(dataSetObj).set("$.columns",dataSetColumnArray).json();
return updatedDataSetReq;
}
The problem is with your currentJsonColumnObject object assigning in for loop.
you are using the same object currentJsonColumnObject for all iterations which is referring to currentJsonColumnArr.get(0).
To solve your issue you need to set a different object for currentJsonColumnObject.
JSONArray jsonArray = JsonPath.parse(responseofotherapi).read("$.columns");
JSONArray dataSetColumnArray = new JSONArray();
JSONArray currentJsonColumnArr= JsonPath.parse(dataSetObj).read("$.columns");
//object will be set inside loop
JSONObject currentJsonColumnObject;
LinkedHashMap<String,Object> currentColumn;
for(int columnNumber = 0; columnNumber < jsonArray.size(); columnNumber++){
currentColumn= (LinkedHashMap<String,Object>)jsonArray.get(columnNumber);
// getting object from `currentJsonColumnArr` instead of using the same.
currentJsonColumnObject= (JSONObject) currentJsonColumnArr.get(columnNumber);
String name = currentColumn.get("name").toString();
currentJsonColumnObject.put("name",name);
currentJsonColumnObject.put("alias",name+" Column Alias ");
currentJsonColumnObject.put("description",name+" Column Description ");
dataSetColumnArray.add(columnNumber,currentJsonColumnObject);
currentColumn.clear();
}
I have a JSON object that looks like this
{"layout":[["12","21","31"],["empty","22","32"],["13","23","33"]]}
I am trying to get the array data within with:
JSONObject layoutJson;
JSONArray layoutData = layoutJson.getJSONArray();
However I end up with a single entry in the array of
[["12","21","31"],["empty","22","32"],["13","23","33"]]
How do I get this out of the JSON object in the form of 3 arrays?
JSONObject layoutJson;
JSONArray layoutData = layoutJson.getJSONArray();
for (int i = 0; i < layoutData.length(); i++) {
JSONObject firstArray = (JSONObject)layoutData.getJSONObject(i);
// Do whatever you want with first array
// you can loop through the first array again
}
This question already has answers here:
How do I print my Java object without getting "SomeType#2f92e0f4"?
(13 answers)
Closed 5 years ago.
The following code is printing hash values instead of Array
JSONObject myjson1 = new JSONObject(expectedResult);
Iterator x = myjson1.keys();
JSONArray jsonArray = new JSONArray();
while (x.hasNext()){
String key = (String) x.next();
jsonArray.put(myjson1.get(key));
System.out.println(x);
}
The output is as follows:
java.util.HashMap$KeyIterator#42a0b130
java.util.HashMap$KeyIterator#3c2a5fb9
java.util.HashMap$KeyIterator#6e68bc46
java.util.HashMap$KeyIterator#3223cb64
java.util.HashMap$KeyIterator#256c426b
PS: Converting Json to Array (key : value) form
Do not use (String) instead use toString()
So
String key = (String) x.next();
jsonArray.put(myjson1.get(key));
System.out.println(x.toString());
And if you want to convert it to string array:
String[] result = jsonArray.values().toArray(new String[0]);
And you can check this one:
how to covert map values into string in Java
I suggest you to use Gson library to manage .json files. It's more accurate, it's more user-friendly and it works very well.
By the way you're asking Java to print the object "x" (Iterator). An object contains the reference to the memory allocation of itself.
You have to ask your software to convert it in a human-readable format, such as String is.
So try to add .toString() method after x invocation.
Try to do something like:
JSONObject myjson1 = new JSONObject(expectedResult);
Iterator x = myjson1.keys();
JSONArray jsonArray = new JSONArray();
while (x.hasNext()){
String key = (String) x.next();
jsonArray.put(myjson1.get(key));
System.out.println(x.toString());
}
I hope to be helpful.
This question already has answers here:
Add data to JSONObject
(3 answers)
Closed 9 years ago.
Whenever I add second JSONObject to JSONArray, it overwrites the previous array object value.
My java servlet code is-
JsonArray ja=new JsonArray();
JsonObject j;
j = new JsonObject();
j.add("uid", j);
j.add("fname", j);
j.add("lname", j);
for(int i=0;i<uid_list.size();i++){
out.println(uid_list.get(i).toString());
out.println(fname_list.get(i).toString());
out.println(lname_list.get(i).toString());
j.addProperty("uid", uid_list.get(i).toString());
j.addProperty("fname", fname_list.get(i).toString());
j.addProperty("lname", lname_list.get(i).toString());
ja.add(j);
out.println(ja.toString());
}
out.println(ja.toString());
and the output is:
abc bcd cde [{"uid":"abc","fname":"bcd","lname":"cde"}] xyz wxy uyw [{"uid":"xyz","fname":"wxy","lname":"uyw"},{"uid":"xyz","fname":"wxy","lname":"uyw"}] [{"uid":"xyz","fname":"wxy","lname":"uyw"},{"uid":"xyz","fname":"wxy","lname":"uyw"}]
can someone please give me solution for this
You are modifying the same instance of JsonObject in the loop. Create new JsonObject in loop,
for(int i=0;i<uid_list.size();i++){
j=new JsonObject();
out.println(uid_list.get(i).toString());
I am building an android app that needs to download and synchronise with an online database, I am sending my query from the app to a php page which returns the relevant rows from a database in JSON format.
can someone please tell me the best way to iterate through a JSON array?
I receive an array of objects:
[{json object},{json object},{json object}]
What is the simplest piece of code I could use to access the JSONObjects in the array?
EDIT: now that I think of it the method I used to iterate the loop was:
for (String row: json){
id = row.getInt("id");
name = row.getString("name");
password = row.getString("password");
}
So I guess I had was somehow able to turn the returned Json into and iterable array. Any Ideas how I could achieve this?
I apologise for my vaguness but I had this working from an example I found on the web and have since been unable to find it.
I think this code is short and clear:
int id;
String name;
JSONArray array = new JSONArray(string_of_json_array);
for (int i = 0; i < array.length(); i++) {
JSONObject row = array.getJSONObject(i);
id = row.getInt("id");
name = row.getString("name");
}
Is that what you were looking for?
I have done it two different ways,
1.) make a Map
HashMap<String, String> applicationSettings = new HashMap<String,String>();
for(int i=0; i<settings.length(); i++){
String value = settings.getJSONObject(i).getString("value");
String name = settings.getJSONObject(i).getString("name");
applicationSettings.put(name, value);
}
2.) make a JSONArray of names
JSONArray names = json.names();
JSONArray values = json.toJSONArray(names);
for(int i=0; i<values.length(); i++){
if (names.getString(i).equals("description")){
setDescription(values.getString(i));
}
else if (names.getString(i).equals("expiryDate")){
String dateString = values.getString(i);
setExpiryDate(stringToDateHelper(dateString));
}
else if (names.getString(i).equals("id")){
setId(values.getLong(i));
}
else if (names.getString(i).equals("offerCode")){
setOfferCode(values.getString(i));
}
else if (names.getString(i).equals("startDate")){
String dateString = values.getString(i);
setStartDate(stringToDateHelper(dateString));
}
else if (names.getString(i).equals("title")){
setTitle(values.getString(i));
}
}
Unfortunately , JSONArray doesn't support foreach statements, like:
for(JSONObject someObj : someJsonArray) {
// do something about someObj
....
....
}
When I tried #vipw's suggestion, I was faced with this exception:
The method getJSONObject(int) is undefined for the type JSONArray
This worked for me instead:
int myJsonArraySize = myJsonArray.size();
for (int i = 0; i < myJsonArraySize; i++) {
JSONObject myJsonObject = (JSONObject) myJsonArray.get(i);
// Do whatever you have to do to myJsonObject...
}
If you're using the JSON.org Java implementation, which is open source, you can just make JSONArray implement the Iterable interface and add the following method to the class:
#Override
public Iterator iterator() {
return this.myArrayList.iterator();
}
This will make all instances of JSONArray iterable, meaning that the for (Object foo : bar) syntax will now work with it (note that foo has to be an Object, because JSONArrays do not have a declared type). All this works because the JSONArray class is backed by a simple ArrayList, which is already iterable. I imagine that other open source implementations would be just as easy to change.
On Arrays, look for:
JSONArray menuitemArray = popupObject.getJSONArray("menuitem");
You are using the same Cast object for every entry.
On each iteration you just changed the same object instead creating a new one.
This code should fix it:
JSONArray jCastArr = jObj.getJSONArray("abridged_cast");
ArrayList<Cast> castList= new ArrayList<Cast>();
for (int i=0; i < jCastArr.length(); i++) {
Cast person = new Cast(); // create a new object here
JSONObject jpersonObj = jCastArr.getJSONObject(i);
person.castId = (String) jpersonObj.getString("id");
person.castFullName = (String) jpersonObj.getString("name");
castList.add(person);
}
details.castList = castList;
While iterating over a JSON array (org.json.JSONArray, built into Android), watch out for null objects; for example, you may get "null" instead of a null string.
A check may look like:
s[i] = array.isNull(i) ? null : array.getString(i);