The problem is not the JSONArray.toString(), as @Selvin mentioned.
From JSONArray source:
/**
* Encodes this array as a compact JSON string, such as:
* <pre>[94043,90210]</pre>
*/
@Override public String toString() {
try {
JSONStringer stringer = new JSONStringer();
writeTo(stringer);
return stringer.toString();
} catch (JSONException e) {
return null;
}
}
/**
* Encodes this array as a human readable JSON string for debugging, such
* as:
* <pre>
* [
* 94043,
* 90210
* ]</pre>
*
* @param indentSpaces the number of spaces to indent for each level of
* nesting.
*/
public String toString(int indentSpaces) throws JSONException {
JSONStringer stringer = new JSONStringer(indentSpaces);
writeTo(stringer);
return stringer.toString();
}
The problem is that you need to convert your ChecklistAnswer to JSON object first for your JSONArray to work properly.
Again from Javadoc:
/**
* A dense indexed sequence of values. Values may be any mix of
* {@link JSONObject JSONObjects}, other {@link JSONArray JSONArrays}, Strings,
* Booleans, Integers, Longs, Doubles, {@code null} or {@link JSONObject#NULL}.
* Values may not be {@link Double#isNaN() NaNs}, {@link Double#isInfinite()
* infinities}, or of any type not listed here.
...
Answer from Nemanja Maksimovic on Stack OverflowThe problem is not the JSONArray.toString(), as @Selvin mentioned.
From JSONArray source:
/**
* Encodes this array as a compact JSON string, such as:
* <pre>[94043,90210]</pre>
*/
@Override public String toString() {
try {
JSONStringer stringer = new JSONStringer();
writeTo(stringer);
return stringer.toString();
} catch (JSONException e) {
return null;
}
}
/**
* Encodes this array as a human readable JSON string for debugging, such
* as:
* <pre>
* [
* 94043,
* 90210
* ]</pre>
*
* @param indentSpaces the number of spaces to indent for each level of
* nesting.
*/
public String toString(int indentSpaces) throws JSONException {
JSONStringer stringer = new JSONStringer(indentSpaces);
writeTo(stringer);
return stringer.toString();
}
The problem is that you need to convert your ChecklistAnswer to JSON object first for your JSONArray to work properly.
Again from Javadoc:
/**
* A dense indexed sequence of values. Values may be any mix of
* {@link JSONObject JSONObjects}, other {@link JSONArray JSONArrays}, Strings,
* Booleans, Integers, Longs, Doubles, {@code null} or {@link JSONObject#NULL}.
* Values may not be {@link Double#isNaN() NaNs}, {@link Double#isInfinite()
* infinities}, or of any type not listed here.
...
In my ChecklistAnwer class i added:
public JSONObject toJsonObject(){
JSONObject json = new JSONObject();
try {
json.put("questionId", questionId);
json.put("checklistId", checklistId);
json.put("answer", answer);
json.put("remark", remark);
} catch (JSONException e) {
e.printStackTrace();
}
return json;
}
and in my other class:
JSONArray answers = new JSONArray();
ChecklistAnswer answer = new ChecklistAnswer(questions.get(id).id, 2, cb.isChecked(), text.getText().toString());
answers.put(answer.toJsonObject());
if i filled the array:
String js = answers.toString(1);
and that returns:
[
{
"answer": true,
"questionId": 1,
"remark": "",
"checklistId": 2
},
{
"answer": false,
"questionId": 4,
"remark": "teesxfgtfghyfj",
"checklistId": 2
},
{
"answer": true,
"questionId": 4,
"remark": "",
"checklistId": 2
},
{
"answer": true,
"questionId": 4,
"remark": "",
"checklistId": 2
},
{
"answer": true,
"questionId": 4,
"remark": "",
"checklistId": 2
},
{
"answer": true,
"questionId": 4,
"remark": "",
"checklistId": 2
},
{
"answer": true,
"questionId": 4,
"remark": "",
"checklistId": 2
}
]
thanks to @Selvin
Take a look at this tutorial. Also you can parse above json like :
JSONArray arr = new JSONArray(yourJSONresponse);
List<String> list = new ArrayList<String>();
for(int i = 0; i < arr.length(); i++){
list.add(arr.getJSONObject(i).getString("name"));
}
Simplest and correct code is:
public static String[] toStringArray(JSONArray array) {
if(array==null)
return new String[0];
String[] arr=new String[array.length()];
for(int i=0; i<arr.length; i++) {
arr[i]=array.optString(i);
}
return arr;
}
Using List<String> is not a good idea, as you know the length of the array.
Observe that it uses arr.length in for condition to avoid calling a method, i.e. array.length(), on each loop.
Use gson. It's got a much friendlier API than org.json.
Collections Examples (from the User Guide):
Gson gson = new Gson();
Collection<Integer> ints = Lists.immutableList(1,2,3,4,5);
//(Serialization)
String json = gson.toJson(ints); ==> json is [1,2,3,4,5]
//(Deserialization)
Type collectionType = new TypeToken<Collection<Integer>>(){}.getType();
Collection<Integer> ints2 = gson.fromJson(json, collectionType);
//ints2 is same as ints
You are right! Even @Sean Patrick Floyd's answer is too much boilterplate to covert a JSON array to string[] or any other type of array class. Rather here is what I find to be elegant:
JsonArray jsonArray = input.getAsJsonArray("key");
Gson gson = new Gson();
String[] output = gson.fromJson(jsonArray , String[].class)
NOTE 1: JsonArray must be an array of strings, for the above example, without any property names. Eg:
{key:["Apple","Orange","Mango","Papaya","Guava"]}
Note 2: JsonObject class used above is from com.google.gson library and not the JSONObject class from org.json library.
Nikita already gave you the correct solution, but here it is, step by step.
I reduced your problem to this minimal test:
import com.google.gson.Gson;
public class TestGSON
{
public static void main( String[] args )
{
// that's your JSON sample
String json = "[{\"reserve_no\":\"20\",\"city\":\"city2\",\"street\":\"street1234\",\"discription\":\"discription123\",\"date\":\"2012-10-22 04:47:54\",\"customer\":\"abc\"}]";
// note: we tell Gson to expect an **array** of Data
Data data[] = new Gson().fromJson(json, Data[].class);
System.out.println(data[0]);
}
}
The problem is that your JSON fragment is actually an array of objects, not just an object (hence the [] around it). So, you need to tell GSon it must expect an array of Data, not just a Data object. By the way, the exception that's thrown when executing your code as-is already told you so:
Exception in thread "main" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2
unless of course it got swallowed by an empty catch block
With respect to the Data class: think twice before you override the toString method like you did here. I would drop that method and just do
System.out.println( data[0].getCity() );
Gson maps json string to your class basing on your class properties names. So Data class has property title which is supposed to be mapped to city in json array. You need to rename you property to city so Gson can figure out where to put city from json array.
Or you can use annotations to explicitly map city to title. Check this: https://sites.google.com/site/gson/gson-user-guide#TOC-JSON-Field-Naming-Support