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How to get values from JSONObject in 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.

search in JSON File, using a loop

I created a JSON file with JAVA.
Now I want to search a String in the JSON file.
JSONObject root = new JSONObject();
JSONObject courseObject1 = new JSONObject();
courseObject1.put("name", "MEA");
courseObject1.put("author", "Mn");
root.put("object", courseObject1);
//------------------------------------
JSONObject courseObject2 = new JSONObject();
courseObject2.put("name", "MES");
courseObject2.put("author", "Ma");
root.put("object2", courseObject2);
I want to know in which courseObject is "MES".
(Maby in the finish programm are more courseObjects)

You can proceed as follows:
for(int i = 0; i < root.length(); i++) {
JSONObject obj = root.getJSONObject(i);
if(obj.getString("name").equals("MES")) {
// Do something with the course
}
}

Convert String to JSON Array from Web Request

i wanted to know how I can convert this string here to an array:
[{"title":"test","birth":"20.05"},{"title":"test","birth":"13.05"},{"title":"test","birth":"13.06"},{"title":"test","birth":"23.06"},{"title":"test","birth":"01.12"},{"title":"test","birth":"01.06"}]
I already found this here:
JSONObject jsnobject = new JSONObject(readlocationFeed);
JSONArray jsonArray = jsnobject.getJSONArray("locations");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject explrObject = jsonArray.getJSONObject(i);
But if I try to make the object I always get null. And here:
JSONArray jsonArray = jsnobject.getJSONArray("locations");
I don't know what I should enter as "locations". Should I enter "[]" ?
Thanks really much for help!
Daniel

I don't know what I should enter as "locations". Should I enter "[]" ?
Nothing readlocationFeed is already a JSONArray. You just need
JSONArray jsonArray = new JSONArray(readlocationFeed);
without
JSONObject jsnobject = new JSONObject(readlocationFeed);
JSONArray jsonArray = jsnobject.getJSONArray("locations");

Shouldn't it be the other way around?
JSONArray jsnArray = new JSONArray(readlocationFeed);
Anyway I suggest you should use GSON for this kind of problem:
Gson gson = new Gson();
MyClass[] arr = gson.fromJson(str, MyClass[].class);
class MyClass{
double birth;
String title;
}

How to read JSON in Java?

I have a JSON String and I got the data element's data to JSONObject. After I read this that resultant string is as follows. I'm using org.json library.
String dataStr = "[{\"name\":\"jhonny\",\"counts\":[\"50\",\"44\",\"46\"],\"url\":\"google\"},
{\"name\":\"john\",\"counts\":[\"344\",\"4\",\"18\"],\"url\":\"yahoo\"}]";
I tried to read the each element like following,
String dataStr = report.get("data").toString();
JSONObject data = new JSONObject(dataStr.substring(1));
System.out.println(data);
But my output is,
{"name":"jhonny","counts":["50","44","46"],"url":"google"}
The output contains only one element. How can I fix this?

JSONArray jsonarray = new JSONArray(datastr);
for(int i=0; i<jsonarray.length(); i++){
JSONObject data= jsonarray.getJSONObject(i);
System.out.println(data);
}

Using the org.json library:
JSONObject obj = new JSONObject("{interests : [{interestKey:Dogs}, {interestKey:Cats}]}");
List<String> list = new ArrayList<String>();
JSONArray array = obj.getJSONArray("interests");
for(int i = 0 ; i < array.length() ; i++){
list.add(array.getJSONObject(i).getString("interestKey"));
}

The problem is you are trying to read JSONArray as JSONObject.
To parse JSONArray you need to do something like: (Not sure which library you are using)
for (int i = 0; i < jsonarray.length(); i++) {
JSONObject jsonobject = jsonarray.getJSONObject(i);
// jsonobject holds the desired element.
}

If you analyze your json string, you will notice that your json string contains multiple json object without outer object like :-
{
"outer":{
{\"name\":\"jhonny\",\"counts\":[\"50\",\"44\",\"46\"],\"url\":\"google\"},
{\"name\":\"jhonny\",\"counts\":[\"50\",\"44\",\"46\"],\"url\":\"google\"}
}
}
The way you are parsing require this kind of json structure. Your json string is actually just a jsonarray. So do like this way :
JSONArray jsonarray = new JSONArray(datastr);
for(int i=0; i<jsonarray.length(); i++){
JSONObject data= jsonarray.getJSONObject(i);
}
For more you can visit this link that gives you good explanation to how to read json in java

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.