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JSON Array parsing where key is missing in the key-value pair

I am trying to parse a JSON Array which looks something like this
"data":["data1","data2","data3"]
If I write JSONArray arr = obj1.getJSONArray("data");, this will provide me with the JSON array but since the key name from key-value pair is missing, how will I retrieve "data1", "data2" and "data3"?

JSON arrays allows for non json children. In this case, the children are of String value:
for(int i=0;i<arr.length();i++) {
String value = arr.getString(i);
}
My syntax might be inaccurate

Assuming this is your JSON,
{"data":["data1","data2","data3"]}
Use the following to retrieve the array,
JSONArray arrJson = jsonData.getJSONArray("data");
String[] arr = new String[arrJson.length()];
for(int i = 0; i < arrJson.length(); i++) {
arr[i] = arrJson.getString(i);
}

JSONArray.add(JSONObject) in for loop is replacing old values in for loop and Array consists of the last values in the loop

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();
}

how to create json array from java string for loop

I have a JAVA for loop which prints the out put as shown below.
inside for loop::{"state":"tess","path":"/content/projectpath/en/men"} inside for loop::{"state":"hello","path":"/content/projectpath/en/women"}
Any my code snippet is as shown below.
for (Value val : values) {
//jsonobj = new JSONObject(val.getString());
out.println("inside for loop::" + val.getString());
// JSONArray jsonarr = val.getString();
}// out.println("::"+jsonobj.toString());
How to get a JSON Array after the for loop which should have the values {"state":"tess","path":"/content/projectpath/en/men"} and {"state":"hello","path":"/content/projectpath/en/women"}

create a JSONArray like this. insert your looping object on list. Finally you will get an array please try it.
JSONArray list = new JSONArray();
list.add(val);

How to clear data from a JSON Array

I am working on a project where I have to clear all the data from a JSON array. There seems to be no method like jsonArray.clear(). Also tried jsonArray = new JSONArray(). That too didn't worked. Suggestions please

Just create a new JSONArray.
JSONArray otherJsonArray = new JSONArray();
Or iterate through the array and remove(int index) the indexes.
http://www.json.org/javadoc/org/json/JSONArray.html#remove(int)

Just put jsonArray = new JSONArray()

Creating a new one will work, unless you have passed it as a parameter to a method in which case you need to modify the referenced object as a new reference will not be seen by the calling method.
So if that is the case, do it backwards, that way you won't get your iterator exceeding bounds:
int startingLength = someJsonArray.length();
for (int i = startingLength - 1; i >= 0; i--) {
someJsonArray.remove(i);
}

And you use that
otherJsonArray is already existing then you use
JSONArray otherJsonArray = new JSONArray("[]");

We can use someJsonArray.pop(index) to remove require record.
We can use this code in loop to remove all records.

I have a situation where I want to remove all the entries from a JSONArray with key "Constants", which is an element in a JSONObject, creating a new JSONArray an assigning it does NOT clear the JSONArray, I have to iterate through the JSONArray and jsonArray.remove(i) on each of them, but there is a second method that works which involves removing the array element, in this case "Constants" completely from the JSONObject and re-adding it as a new JSONArray.
Hereis code with assignment of new array, which does not work, the JSONArray remained unchanged: (I tried both above suggestions for new JSONArray(); and new JSONArray("[]");
JSONObject jsonObj = new JSONObject(metadataOriginalJSON);
if (jsonObj.isJSONArray("Constants")) {
JSONArray constantsArray = jsonObj.getJSONArray("Constants");
constantsArray = new JSONArray();
metadataConstantsRemoved = jsonObj.toString();
}
Here is code for the iteration through the JSONArray which worked:
JSONObject jsonObj = new JSONObject(metadataOriginalJSON);
if (jsonObj.isJSONArray("Constants")) {
JSONArray constantsArray = jsonObj.getJSONArray("Constants");
int i = 0;
int arrayLenSanityCheckPreventEndlessLoop = constantsArray.length();
while (constantsArray.length() > 0 && i < arrayLenSanityCheckPreventEndlessLoop) {
constantsArray.remove(0);
i++;
}
metadataConstantsRemoved = jsonObj.toString();
}
The 2nd method that works by removing the entire JSONArray element and re-adding it to the JSONObject:
JSONObject jsonObj = new JSONObject(metadataOriginalJSON);
if (jsonObj.isJSONArray("Constants")) {
jsonObj.remove("Constants");
jsonObj.put("Constants", new JSONArray());
metadataConstantsRemoved = jsonObj.toString();
}

JSON Array iteration in Android/Java

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);