Reputation: 47
I have a JSON file which is an JSON ARRAY with some JSON Objects and I want to remove the entire json Object if the value of longitude or latitude is an empty string "".
I am using the library org.json.simple. Here is my json file:
[ { "Longitude": 9.96233,
"Latitude": 49.80404 },
{
"Longitude": 6.11499,
"Latitude": 50.76891
},
{ "Longitude": 6.80592,
"Latitude": 51.53548
},
{
"Longitude": 9.50523,
"Latitude": 51.31991 },
{
"Longitude": ""
"Latitude": ""
},
{
"Longitude": 9.93368,
"Latitude": ""
},
{
"Longitude": 11.56122,
"Latitude": 48.14496
},
{
"Longitude": 13.34253,
"Latitude": 52.5319
},
{
"Longitude": 6.11327,
"Latitude": 50.77715
},
{
"Longitude": ""
"Latitude": ""
}
]
and here's where I am stuck. :
JSONParser jsonParser = new JSONParser();
try (FileReader reader = new FileReader ("output.json")) {
Object obj = jsonParser.parse(reader);
JSONArray list = (JSONArray) obj;
list.forEach(node -> {
String vari = (String)((JSONObject)node).get("longitude").toString();
if (vari==null) {
((JSONObject) node).remove();
System.out.println("deleted");
}
}
...
Any suggestions how can I change my code ?
Upvotes: 1
Views: 2191
Reputation: 12285
You need to remove the node from the list but because of concurrent modification problem (modifying the list you are looping) you need another list.
I think it is easiest to collect into the new list all the nodes that qualify so like:
@SuppressWarnings("unchecked")
@Test
public void test() throws Exception {
JSONParser jsonParser = new JSONParser();
JSONArray listNonNull = new JSONArray();
try (FileReader reader = new FileReader("output.json")) {
JSONArray list = (JSONArray) jsonParser.parse(reader);
((Collection<JSONObject>)list).forEach(node -> {
// here any check that qualifies the node like also checking "Latitude"
// Also no need to cast to a String
Object vari = node.get("Longitude");
if (vari != null && !vari.equals("")) {
listNonNull.add(node);
}
});
} catch (Exception e) {
throw e;
}
}
If you wish to use only the original list you can collect items to be removed to an another list and use it to remove nodes from the original list:
public void test2() throws Exception {
JSONParser jsonParser = new JSONParser();
JSONArray toBeRemoved = new JSONArray();
try (FileReader reader = new FileReader("output.json")) {
JSONArray list = (JSONArray) jsonParser.parse(reader);
((Collection<JSONObject>) list).forEach(node -> {
Object vari = node.get("Longitude");
// here any check that qualifies the node like also checking "Latitude"
if (vari != null && !vari.equals("")) {
return; // not to be removed
}
toBeRemoved.add(node);
});
list.removeAll(toBeRemoved);
} catch (Exception e) {
throw e;
}
}
Upvotes: 1
Reputation: 204
JSONParser jsonParser = new JSONParser();
try (FileReader reader = new FileReader("output.json")) {
Object obj = jsonParser.parse(reader);
JSONArray list = (JSONArray) obj;
ArrayList<JSONObject> objList = (ArrayList<JSONObject>) list.stream().filter(node -> {
String longitude = ((JSONObject) node).get("Longitude").toString();
String latitude = ((JSONObject) node).get("Latitude").toString();
if (longitude.isEmpty() || latitude.isEmpty()) {
return false;
}
return true;
}).collect(Collectors.toList());
} catch (IOException | ParseException e) {
e.printStackTrace();
}
Upvotes: 0