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"));
}
Answer from Saad Asad on Stack OverflowTake 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.
Here you get JSONObject so change this line:
JSONArray jsonArray = new JSONArray(readlocationFeed);
with following:
JSONObject jsnobject = new JSONObject(readlocationFeed);
and after
JSONArray jsonArray = jsnobject.getJSONArray("locations");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject explrObject = jsonArray.getJSONObject(i);
}
Input String
[
{
"userName": "sandeep",
"age": 30
},
{
"userName": "vivan",
"age": 5
}
]
Simple Way to Convert String to JSON
public class Test
{
public static void main(String[] args) throws JSONException
{
String data = "[{\"userName\": \"sandeep\",\"age\":30},{\"userName\": \"vivan\",\"age\":5}] ";
JSONArray jsonArr = new JSONArray(data);
for (int i = 0; i < jsonArr.length(); i++)
{
JSONObject jsonObj = jsonArr.getJSONObject(i);
System.out.println(jsonObj);
}
}
}
Output
{"userName":"sandeep","age":30}
{"userName":"vivan","age":5}
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.
...
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
Look like you want to store name and location in an array, if yes then
for(int i=0; i < jLocation.length(); i++){
arr[0] = jLocation.getJSONObject(i).getString("name");
arr[1] = jLocation.getJSONObject(i).getString("location");
}
Note - This code assume that you only have one name and location. However I sugegst you to do something like below:
Create a Location class, e.g. below
public class Location {
private String name;
private String location;
public Location(String name, String location) {
this.name = name;
this.location = location;
}
public String getName() {
return name;
}
public String getLocation() {
return location;
}
}
Then use it like below:
public static void main(String[] args) {
List<Location> locations = new ArrayList<Location>();
for(int i=0; i < jLocation.length(); i++){
String name = jLocation.getJSONObject(i).getString("name");
String location = jLocation.getJSONObject(i).getString("location");
locations.add(new Location(name, location));
}
}
Try this
//First initiate string
String value1;
String value2;
//Read json
for(int i-0;i < jLocation.length();i++){
value1 = jLocation.getJSONObject(i).getString("name");
value2 = jLocation.getJSONObject(i).getString("location");
}
//Create Stting array
String[ ] arr = {value1,value2};
It will use to add only one value to array.
I prefer ArrayList. Then you can add all the data to ArrayList
Issue is here:
JSONArray myjsonarray = myjson.toJSONArray(temparray);
Solution:
JSONArray myjsonarray = new JSONArray(myJSON);
// myJSON is String
Now here you are having JSONArray, iterate over it and prepare ArrayList of whatever types of you want.
here you get JSONArray so change
JSONArray myjsonarray = myjson.toJSONArray(temparray);
line as shown below
JSONArray jsonArray = new JSONArray(readlocationFeed);
and after
JSONArray jsonArray = new JSONArray(readlocationFeed);
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject explrObject = jsonArray.getJSONObject(i);
explrObject.getString("caption");
}
Something like this:
ArrayList<String> jsonStringToArray(String jsonString) throws JSONException {
ArrayList<String> stringArray = new ArrayList<String>();
JSONArray jsonArray = new JSONArray(jsonString);
for (int i = 0; i < jsonArray.length(); i++) {
stringArray.add(jsonArray.getString(i));
}
return stringArray;
}
You could try something like:
new JSONArray(jsonString)
or if it is a property:
jsonObject.getJSONArray(propertyName)
For anyone else who might need this:
String jsonString = "[\"string1\",\"string2\",\"string3\"]";
ObjectMapper mapper = new ObjectMapper();
List<String> strings = mapper.readValue(jsonString, List.class);
As ryzhman said, you are able to cast it to a List, but only of the object (JSONArray in ryzhman's case) extends the ArrayList class. You don't need an entire method for this. You can simply:
List<String> listOfStrings = new JSONArray(data);
Or if you are using IBM's JSONArray (com.ibm.json.java.JSONArray):
List<String> listOfStrings = (JSONArray) jsonObject.get("key");
To have a string value inside your JSON array, you must remember to backslash escape your double-quotes in your Java program. See the declaration of s below.
String s = "[[\"110917 \", 3.0099999999999998, -0.72999999999999998, 2.8500000000000001, 2.96, 685.0, 38603.0], [\"110917 \", 2.71, 0.20999999999999999, 2.8199999999999998, 2.8999999999999999, 2987.0, 33762.0]]";
Your code in the main() method works fine. Below is just a minor modification of your code in the main() method.
System.out.println("String to Json Array Stmt");
JsonParser parser = new JsonParser();
JsonElement tradeElement = parser.parse(s);
JsonArray trade = tradeElement.getAsJsonArray();
System.out.println(trade);
Lastly, remember to prefix your statement "com.google.gson.*" with the keyword "import", as shown below.
import com.google.gson.*;
I don't see the problem. This code runs fine for me:
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonParser;
public class GsonExample {
public static void main(String[] args) {
String s= "[[\"110917\", 3.0099999999999998, -0.72999999999999998," +
"2.8500000000000001, 2.96, 685.0, 38603.0], [\"110917\", 2.71," +
"0.20999999999999999, 2.8199999999999998, 2.8999999999999999," +
"2987.0, 33762.0]]";
JsonParser parser = new JsonParser();
JsonElement elem = parser.parse( s );
JsonArray elemArr = elem.getAsJsonArray();
System.out.println( elemArr );
}
}
The only problem maybe is that you failed to properly escape the double quotes in your s string literal.
Using a stream you could convert it like so:
String s = "[\"A\",\"B\",\"C\",\"D\",\"E\"]";
String[] arr = Arrays.stream(s.substring(1, s.length()-1).split(","))
.map(e -> e.replaceAll("\"", ""))
.toArray(String[]::new);
You could also use a JSON library (which might be the prefered way). For example using Jackson:
String s = "[\"A\",\"B\",\"C\",\"D\",\"E\"]";
ObjectMapper mapper = new ObjectMapper();
String[] arr = mapper.readValue(s, String[].class);
ArrayList<String> jsonStringToArray(String jsonString) throws JSONException {
ArrayList<String> stringArray = new ArrayList<String>();
JSONArray jsonArray = new JSONArray(jsonString);
for (int i = 0; i < jsonArray.length(); i++) {
stringArray.add(jsonArray.getString(i));
}
return stringArray;
}