I have a JSONObject, like the output in this link:
https://hadoop.apache.org/docs/r1.0.4/webhdfs.html#GETFILESTATUS
I woul dlike to get the pathSuffix (file names) and the modificationTime (Dates) values in a JSON Array, like this:
[
{ file1, date
},
{ file1, date
},
{ file1, date
},
.
.
.
]
My code is the following:
JsonObject fileStatuses = jsonObject.getJsonObject("FileStatuses");
JsonArray fileStatus = (JsonArray) fileStatuses.getJsonArray("FileStatus");
for (int i = 0; i < fileStatus.size(); i++) {
JsonObject rec = fileStatus.getJsonObject(i);
String pathSuffix = rec.getString("pathSuffix");
String modificationTime = rec.getJsonNumber("modificationTime").toString();
long a = Long.parseLong(modificationTime);
Date modificationTimeDate = new Date(a);
JsonObject jo = Json.createObjectBuilder()
.add("list", Json.createArrayBuilder()
.add(Json.createObjectBuilder()
.add(pathSuffix, (JsonValue) modificationTimeDate)
))
.build();
logger.info("JSON object is '{}'", jo);
I got this Exception:
Exception in thread "main" java.lang.ClassCastException: java.util.Date incompatible with javax.json.JsonValue
How can I create a JsonArray that contain the values of Pathsuffix and ModificationTime like (key, value) ? Thanks
If you want to store a JSON-Object filename:modificationTime you can accomplish this by constructing a Map that holds your key and value pairs:
JsonArrayBuilder builder = Json.createArrayBuilder();
for (int i = 0; i < fileStatus.size(); i++) {
JsonObject rec = fileStatus.getJsonObject(i);
String timeStamp = rec.get("modificationTime").toString();
Map<String, Object> jsonMapping = Map.of(rec.getString("pathSuffix"),
timeStamp);
builder.add(Json.createObjectBuilder(jsonMapping));
}
After that, for the json from your Link, builder.build() will yield a JsonArray like this:
[
{
"a.patch":"1320171722771" // FileStatus.pathSuffix : FileStatus.modificationTime
},
{
"bar":"1320895981256"
}
]
Unless you need to construct a certain Date from the timestamp I stronlgy advice to store the acquired timestamp as is. This is because creating any LocalDate (or worse: Date) from a timestamp will yield inaccurate dates unless you consider the TimeZones of both where the file modification happened and where the modificationTime value is read.
json does not support a time type, that is the reason for the error. What you need to do is to change that into a type json can use. That might be a string that represents the time (choose the formating yourself, so you are sure, that when reading it out again you have consistent data) or easier you just keep the long value used.
Here you cansee what json can use:
https://www.json.org/json-en.html
try this json structure
[
{
fileName:"test.java",
modificationTime:"2021-03-02 xx:xx:xx"
}，
{
fileName:"test2.java",
modificationTime:"2021-03-01 xx:xx:xx"
}
]
Related
I have following JSONObject (not array, which I don't mind to convert). I am trying to do two things:
get the count of genre entry as "poetry" (count = 2).
get the key value of author name and genre:
authorName = malcolm
genreName = newsarticle
authorName = keats
genreName = poetry
{ "AddressBook" :{
"Details" :{
"authorname" :{
"Author-malcolm":{
"genre" :"poetry"
}
"Author-keats":{
"genre" :"poetry"
}
}
}
}
}
Code which I tried:
public static void main(String[] args) throws Exception, IOException, ParseException {
JSONParser parser = new JSONParser();
Object obj = parser.parse(new FileReader("My path to JSON"));
JSONObject jsonObject = (JSONObject) obj;
JSONArray arrayhere = new JSONArray();
arrayhere.add(obj);
System.out.println(arrayhere);
int count = 0;
for(int i = 0; i < arrayhere.size(); i++) {
JSONObject element = arrayhere.getJSONObject(i);//The method getJSONObject(int) is undefined for the type JSONArray
String branchName = element.getString("genre");//The method getString(String) is undefined for the type JSONObject
if(branchName.equals("poetry")) {
count ++;
}
}
System.out.println("Count f0r poetry genre=" + count);
}
}
I have looked at solutions all over. There is no question similar to this at stackoverflow. I am not sure if the procedure is correct.
A few problems here.
First, I'm not sure where you got that example JSON but you can't work with that. That's not even valid JSON Formatting.
Looks like you want something like this:
{
AddressBook:
[
{
authorname: "author-malcom",
genre:"poetry"
},
{
authorname: "author-keats",
genre: "poetry"
}
]
}
That's the structure you're trying to create in JSON.
So, you're parsing this in from a file into a JSONObject that has a key called AddressBook inside of it. That key points to an array of JSONObjects representing authors. Each of those objects will have a key called genre. You're trying to access the genre key and count on a condition.
What you did above was create attempt to create a JSONObject from an invalid string, and then add the entire JSONObject itself into the JSONArray. JSONArray.add() doesn't convert an object to an array, it literally adds it onto the array.
jsonObj => {"Name":"name1","Id":1000}
jsonArray.add(jsonObj)
jsonArray => [{"Name":"name1","Id":1000}]
That's what you did in your code above. You didn't create an array from a JSONObject, you added an object to the array.
Proper use is going to look like:
Object obj = parser.parse(new FileReader("path_to_file"));
JSONObject jobj = (JSONObject) obj;
//access key AddressBook
JSONArray author_array = jobj.getJSONArray("AddressBook");
int poetry = 0;
for(int i = 0; i < author_array.length(); i++) {
JSONObject author = (JSONObject) author_array.get(i);
if(author.getString("genre").equals("poetry")) {
poetry++;
}
}
To summarize, you're problems come from a lack of understanding about JSON Formatting and how to access elements within a JSON Object.
Paste in the sample JSONObject I gave you above here. That site will let you visualize what you're working with.
I want to parse an array from Server but I can't obtain the array
Here is the jsonString Successfully got :
{
"status":"OK",
"message":"this is your start and end coordinates",
"data":"{\"start\":[\"35.778763\",\"51.427360\"],\"end\":[\"35.768779, 51.415002\"]}"
}
I want the Double Values from data arraylist:
//try/catch
Log.d(TAG, "Passes here");
JSONObject jObject = new JSONObject(jsonString);
JSONArray jData = jObject.getJSONArray("data");
Log.d(TAG, "Not PAASING HERE !!! ");
JSONArray jArrayStart = (JSONArray) jData.get(0);
JSONArray jArrayEnd = (JSONArray) jData.get(1);
latitudeStart = (Double) jArrayStart.get(0);
longtitudeStart = (Double) jArrayEnd.get(1);
latitudeEnd = (Double) jArrayEnd.get(0);
longtitudeEnd = (Double) jArrayEnd.get(1);
What you're trying to parse, is a string.
{
"status": "OK",
"message": "this is your start and end coordinates",
"data": "{\"start\":[\"35.778763\",\"51.427360\"],\"end\":[\"35.768779, 51.415002\"]}"
}
So it works like this:
//first, retrieve the data from the response JSON Object from the server
JSONObject response = new JSONObject(jsonString);
String status = response.getString("status");
String message = response.getString("message");
//Note this: "data" is a string as well, but we'll have to parse that later.
String data = response.getString("data");
//get the doubles from the arrays from the "data" component.
JSONObject dataObject = new JSONObject(data);
JSONArray start = dataObject.getJSONArray("start");
JSONArray end = dataObject.getJSONArray("end");
for (int i = 0; i < start.length(); i++) {
String value = start.getString(i);
//do something with the start String (parse to double first)
}
for (int i = 0; i < end.length(); i++) {
String value = end.getString(i);
//do something with end String (parse to double first)
}
So data is actually a String, but represents a JSONObject (which you'll have to parse), which, in its turn, contains two JSONArrays.
If data was a JSONObject instead of a String, the JSON would have looked like this:
{
"status": "OK",
"message": "this is your start and end coordinates",
"data": {
"start": [
"35.778763",
"51.427360"
],
"end": [
"35.768779", //note that in your example, this quote is missing (first quote on next line too)
"51.415002"
]
}
}
The value of data is not a JSONArray its JSONObject
Explanation
JSONObject will be surrounded by {}
JSONArray will be surrounded by []
data is not an array, it is a json object and therefore you can not access it the way you are doing.
If you want to fetch start array from json object "data" then use below
jObject.optJSONObject("data").optJSONArray("start");
same thing can be used to retrieve "end" json array.
then use optJSONObject() and/or optString() API to retrieve required value from json array.
Alright. I have a JSON Object sent to me from a server which contains the following data:
{
"result":
[
{"status":"green","type":"data1"},
{"status":"green","type":"data2"},
{"status":"green","type":"data3"}
],
"status":"ok"
}
The data I want to get is the status for the three status values. Data1, data2, and data3 always show up in that order, so I'm now trying to grab the data by index (e.g. data1 = index 0, data2 = index 1, data3 = index 2). How do I do that?
Try following:
String stat1;
String stat2;
String stat3;
JSONObject ret; //contains the original response
//Parse to get the value
try {
stat1 = ret.getJSONArray("results").getJSONObject(0).getString("status");
stat2 = ret.getJSONArray("results").getJSONObject(1).getString("status");
stat3 = ret.getJSONArray("results").getJSONObject(2).getString("status");
} catch (JSONException e1) {
e1.printStackTrace();
}
You would use JSONObject and JSONArray, the entire string is one JSONObject so you would construct one with it.
JSONObject object = new JSONObject(YOUR_STRING_OF_JSON);
Then you can access it with different get methods depending upon your expected type.
JSONArray results = object.getJSONArray("result"); // This is the node name.
String status = object.getString("status");
for (int i = 0; i < results.length(); i++) {
String resultStatus = results.getJSONObject(i).getString("status");
String type = results.getJSONObject(i).getString("type");
Log.w("JSON Result #" + i, "Status: " + resultStatus + " Type: " + type);
}
You need to surround it with a try/catch because JSON access can throw a JSONException.
Try re-factoring via a forEach loop
var testData =
{
"result":
[
{"status":"green","type":"data1"},
{"status":"green","type":"data2"},
{"status":"green","type":"data3"}
],
"status":"ok"
};
var output = new Object;
var resultSet = new Object;
resultSet = testData.result;
resultSet.forEach(function(data)
{
theStatus = data['status'];
theType = data['type']
output[theType] = theStatus;
});
console.log( output['data1'] );
If you've got your models setup to mirror that data set, then you can let GSON (https://code.google.com/p/google-gson/) do a lot of your work for you.
If you want a bit more control, and want to parse the set yourself you can use JSONObject, JSONArray. There's an example of parsing and assembling a json string here: Android create a JSON array of JSON Objects
I have problem when trying to parse with minimum value to map in Android.
There some sample JSON format with more information ex:
[{id:"1", name:"sql"},{id:"2",name:"android"},{id:"3",name:"mvc"}]
This that example most common to use and easy to use just use getString("id") or getValue("name").
But how do I parse to map using this JSON format with just only string and value minimum format to java map collection using looping. And because the string json will always different one with another. ex:
{"1":"sql", "2":"android", "3":"mvc"}
Thank
You need to get a list of all the keys, loop over them and add them to your map as shown in the example below:
String s = "{menu:{\"1\":\"sql\", \"2\":\"android\", \"3\":\"mvc\"}}";
JSONObject jObject = new JSONObject(s);
JSONObject menu = jObject.getJSONObject("menu");
Map<String,String> map = new HashMap<String,String>();
Iterator iter = menu.keys();
while(iter.hasNext()){
String key = (String)iter.next();
String value = menu.getString(key);
map.put(key,value);
}
My pseudocode example will be as follows:
JSONArray jsonArray = "[{id:\"1\", name:\"sql\"},{id:\"2\",name:\"android\"},{id:\"3\",name:\"mvc\"}]";
JSON newJson = new JSON();
for (each json in jsonArray) {
String id = json.get("id");
String name = json.get("name");
newJson.put(id, name);
}
return newJson;
I have this JSON to parse
{"files_informations": {
"row":{"value":"artist1"},
"row":{"value":"artist2"}
}
}
I would like to know how can I get the first value artist1 and then the second one artist2
This is what I am doing :
JSONObject myObject = jObject.getJSONObject("files_informations");
JSONObject rowObject = myObject.getJSONObject("row");
Iterator<JSONObject> rowIt = rowObject.keys();
while (rowIt.hasNext()) {
JSONObject tmp = rowIt.next();
Log.e("", tmp.getString("value"));
}
I got java.lang.classCastException for this JSONObject tmp = rowIt.next();
So there are my two questions :
Do I need to use iterators in this
case ?
How do one should use them ?
Edit :
Should the JSON looks like this ?
{"files_informations": [
"row":{"value":"artist2"},
"row":{"value":"artist1"}
]
}
rowIt.next() is "row" String in this case.
Refactor your JSON to this:
{"files_informations":
[ {"value":"artist2"},
{"value":"artist1"} ] }
Or even this:
{ "files_informations": [ "artist2", "artist1" ] }
and then use:
JSONArray artistsArr = myObject.getJSONArray("files_informations");
for (int i = 0; i < artistsArr.size(); i++) {
// first case
Log.d(TAG, artistsArr.get(i).getString("value"));
// Second case
Log.d(TAG, artistsArr.getString(i));
}
Iterators are not supported in JSONArrays, however you can convert them to plain Java arrays/lists if you really need it.