Parsing JSON without root in JAVA

Question

I have Json like:

{"created_at":"2014","name":"solicitice"}
{"created_at":"2015","name":"hior"}

.....

I am trying below code to get values of all variables: ....

JSONObject jsonObj = new JSONObject(sb.toString());
for (int i = 0; i < jsonObj.length(); i++) {
 System.out.println(jsonObj.get("created_at"));
}

but it is printing only few lines of same value . Also ArrayList is not effective in this case.

• Jos: are you getting some error? also provide an example where its failing..
• xlecoustillier: The provided sample is not valid JSON. Should be enclosed in [] and comma separated.
• mezzodrinker: @X.L.Ant Maybe their input is not a JSON array but rather a list of JSON objects separated by a newline?
• xlecoustillier: @flashdrive2049 Why not, but in this case, JsonParser won't be able to parse that at once AFAIK. The objects will have to be splitted into an array before getting parsed one by one.
• mezzodrinker: @X.L.Ant That's why I suggested using a StringReader wrapped with a BufferedReader in my answer.

Answer 1

If your input as a string is:

"{\"created_at\":\"2014\",\"name\":\"solicitice\"}\n{\"created_at\":\"2015\",\"name\":\"hior\"}"

and it is guaranteed that there is exactly one object per line, you can use a StringReader combined with a BufferedReader to read those objects and then read their values. For example like this:

String input = "...";
try (StringReader sr = new StringReader(input); BufferedReader in = new BufferedReader(sr)) {
 String line;
 while ((line = in.readLine()) != null) {
 JSONObject object = new JSONObject(line);
 System.out.println(object.get("created_at"));
 }
} catch (IOException e) {
 // this should not happen but let's log it anyway
 e.printStackTrace();
}

This will read every line in input, transform it into a JSONObject and print its created_at field to the standard output.

Answer 2

Because you should define it as json array, not json object. Try:

JSONArray jsonArr = new JSONArray(sb.toString());
for (int i = 0; i < jsonArr.length(); i++) {
 System.out.println(jsonArr.get(i).get("created_at"));
}

• mezzodrinker: If the two lines that @Aquarius24 added to their question are their actual input, this would cause an error. A JSON array is defined by an opening bracket [, followed by an arbitrary amount of values separated by comma , and a closing bracket ].
• HakkiBuyukcengiz: it depends on the json library you used. Btw, what was the library?
• Aquarius24: I am using import org.json.JSONArray; import org.json.JSONObject

Answer 3

Few Corrections,

1.) Json String is not correct, should be in form of array

2.) Use JsonArray to pass, then loop, get JsonObject, then get values through keys.

public static void main(String[] args) throws JSONException {
 String s = "[{\"created_at\":\"2014\",\"name\":\"solicitice\"},{\"created_at\":\"2015\",\"name\":\"hior\"}]";
 JSONArray jsonArr = new JSONArray(s);
 for (int i = 0; i < jsonArr.length(); i++) {
 JSONObject jsonObj = (JSONObject) jsonArr.get(i);
 System.out.println(jsonObj.get("created_at"));
 }
 }

output

2014
2015

Answer 4

 StringBuffer jsonStr = new StringBuffer("[{\"created_at\":\"2014\",\"name\":\"solicitice\"},{\"created_at\":\"2015\",\"name\":\"hior\"}]");
 JsonParser jsonParser = new JsonParser();
 JsonArray jsonArray = new JsonArray();
 jsonArray = jsonParser.parse(jsonStr.toString()).getAsJsonArray();
 System.out.println("JSON Array: " + jsonArray);
 for(JsonElement json: jsonArray){
 System.out.println("JSON ELEMENT: " + json);
 System.out.println("NAME: " + json.getAsJsonObject().get("name"));
 System.out.println("CREATED_AT: " + json.getAsJsonObject().get("created_at"));
 }