Develop Reference

how to fetch and validate csv header in open csv?

I want to fetch header from csv file . If I am not use this skipLines then I will get header at 0 index array . But I want to fetch header directly using HeaderColumnNameMappingStrategy but it will not work with my code.
I also want to validate header column list ( like csv had not allowed to contain extra column)
I had also check this How to validate the csv headers using opencsv but it was not helpful to me.
#SuppressWarnings({ "unchecked", "rawtypes" })
public Map<String, Object> handleStockFileUpload(MultipartFile file, Long customerId) {
Map<String, Object> responseMap = new HashMap<>();
responseMap.put("datamap", "");
responseMap.put("errormap", "");
responseMap.put("errorkeys", "");
List<Map<String, Integer>> list = new ArrayList<>();
List<StockCsvDTO> csvStockList = new ArrayList<>();
try {
String fileName = new SimpleDateFormat("yyyy_MM_dd_HHmmss").format(new Date()) + "_" + file.getOriginalFilename();
responseMap.put("filename", fileName);
File stockFile = new File(productsUploadFilePath + fileName);
stockFile.getParentFile().mkdirs();
FileOutputStream fos = new FileOutputStream(stockFile);
fos.write(file.getBytes());
fos.close();
CsvTransfer csvTransfer = new CsvTransfer();
ColumnPositionMappingStrategy ms = new ColumnPositionMappingStrategy();
ms.setType(StockCsv.class);
Reader reader = Files.newBufferedReader(Paths.get(productsUploadFilePath + fileName));
CSVReader csvReader = new CSVReader(reader);
CsvToBean cb = new CsvToBeanBuilder(reader)
.withType(StockCsv.class)
.withMappingStrategy(ms)
.withSkipLines(1)
.build();
csvTransfer.setCsvList(cb.parse());
reader.close();
csvStockList = csvTransfer.getCsvList();
} catch (Exception e) {
e.printStackTrace();
responseMap.put("status", "servererror");
}
responseMap.put("datamap", csvStockList);
return responseMap;
}

I found the following solution:
Use #CsvBindByName with HeaderColumnNameMappingStrategy,e.g. annotate your bean properties with #CsvBindByName:
public static class HollywoodActor {
private int id;
#CsvBindByName(column = "First Name")
private String firstName;
#CsvBindByName(column = "Last Name")
private String lastName;
// getter / setter
}
Add a method like this:
public class CsvParser {
public <T> ParseResult<T> parseByPropertyNames(Reader csvReader, Class<T> beanClass) throws IOException {
CSVReader reader = new CSVReaderBuilder(csvReader).withCSVParser(new
CSVParserBuilder().build()).build();
CsvToBean<T> bean = new CsvToBean();
HeaderColumnNameMappingStrategy<T> mappingStrategy = new HeaderColumnNameMappingStrategy();
mappingStrategy.setType(beanClass);
bean.setMappingStrategy(mappingStrategy);
bean.setCsvReader(reader);
List<T> beans = bean.parse();
return new CsvParseResult<>(mappingStrategy.generateHeader(), beans);
}
and also don't forget to add public class ParseResult
public class ParseResult <T> {
private final String[] headers;
private final List<T> lines;
// all-args constructor & getters
}
Use then use them in your code:
String csv = "Id,First Name,Last Name\n" + "1, \"Johnny\", \"Depp\"\n" + "2, \"Al\", \"Pacino\"";
CsvParseResult<HollywoodActor> parseResult = parser
.parseByPropertyNames(new InputStreamReader(new ByteArrayInputStream(csv.getBytes(StandardCharsets.UTF_8), HollywoodActor.class)));
From ParseResult.headers you can get actual headers from which were in your .csv file. Just compare them with what's expected.
Hope that helps!

Here I was comparing my csvHeader with originalHeader:
List<String> originalHeader = fileUploadUtility.getHeader(new StockCsv());
List<String> invalidHeader = csvHeader.stream().filter(o -> (originalHeader.stream().filter(f -> f.equalsIgnoreCase(o)).count()) < 1).collect(Collectors.toList());
if(null != invalidHeader && invalidHeader.size() > 0 && invalidHeader.toString().replaceAll("\\[\\]", "").length() > 0) {
msg = "Invalid column(s) : " + invalidHeader.toString().replace(", ]", "]") + ". Please remove invalid column(s) from file.";
resultMap.put(1, msg);
}
public List<String> getHeader(T pojo) {
// TODO Auto-generated method stub
final CustomMappingStrategy<T> mappingStrategy = new CustomMappingStrategy<>();
mappingStrategy.setType((Class<? extends T>) pojo.getClass());
String header[] = mappingStrategy.generateHeader();
List<String> strHeader = Arrays.asList(header);
return strHeader;
}

Here is an alternative to your present problem.First, define what you expect your headers to look like. For example:
public static final ArrayList<String> fileFormat = new ArrayList<> (Arrays.asList("Values1", "Values2", "Values3", "Values4"));
Now, write a method to return custom errors if any exist:
public String validateCsvFileDetails(MultipartFile file, Set<String> requiredHeadersArray) {
Set<String> errors = new HashSet<>();
try {
InputStream stream = file.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
String headerLine = reader.readLine();
if (Objects.isNull(headerLine))
return "The file has no headers, please ensure it has the correct upload format";
List<String> headersInFileList;
String[] headersInFileArray;
if (headerLine.contains(",")) {
headersInFileArray = StringUtils.split(headerLine, ",");
headersInFileList = Arrays.asList(headersInFileArray);
} else//the headerline has only one headerfield
{
headersInFileList = Collections.singletonList(headerLine);
}
for (String header : requiredHeadersArray) {
if (!headersInFileList.contains(header))
errors.add("The file has the wrong header format, please ensure " + header + " header is present");
}
//if there are errors, return it
if (!errors.isEmpty())
return sysUtils.getStringFromSet(errors);
//Ensure the csv file actually has values after the header, but don't read beyond the first line
String line;
int counter = 0;
while ((line = reader.readLine()) != null) {
counter++;
if (counter > 0)
break;
}
//if line is null return validation error
if (Objects.isNull(line))
return "Cannot upload empty file";
} catch (Exception e) {
logger.error(new Object() {
}.getClass().getEnclosingMethod().getName(), e);
return "System Error";
}
return null;
}
Now you can validate you file headers as follows:
String errors = validateCsvFileDetails(file, new HashSet<>(fileFormat));
if (errors != null)
return error
//proceed

Give this a try using captureHeader as a pre-filter:
...
private class CustomHeaderColumnNameMappingStrategy<T> extends HeaderColumnNameMappingStrategy {
private String[] expectedHeadersOrdered = {"Column1", "Column2", "Column3", "Column4", "Column5"};
#Override
public void captureHeader(CSVReader reader) throws IOException, CsvRequiredFieldEmptyException {
String[] actualCsvHeaders = reader.peek();
String actualHeader, expectedHeader;
if (expectedHeadersOrdered.length > actualCsvHeaders.length) {
throw new CsvRequiredFieldEmptyException("Missing header column.");
} else if (expectedHeadersOrdered.length < actualCsvHeaders.length) {
throw new IOException("Unexpected extra header column.");
}
// Enforce strict column ordering with index
// TODO: you might want to employ simple hashMap, List, set, etc. as needed
for (int i=0; i<actualCsvHeaders.length; i++) {
actualHeader = actualCsvHeaders[i];
expectedHeader = expectedHeadersOrdered[i];
if ( ! expectedHeader.equals(actualHeader) ) {
throw new IOException("Header columns mismatch in ordering.");
}
}
super.captureHeader(reader); // Back to default processing if the headers include ordering are as expected
}
}
CustomHeaderColumnNameMappingStrategy yourMappingStrategy = new CustomHeaderColumnNameMappingStrategy<YourPOJO>();
ourMappingStrategy.setType(YourPOJO.class);
try {
pojosFromCsv = new CsvToBeanBuilder<YourPOJO>(new FileReader(csvFile))
.withType(YourPOJO.class)
.withMappingStrategy(yourMappingStrategy)
.build();
pojosFromCsv.stream();
}
Inspired by Using captureHeader in OpenCSV

"Cannot deserialize instance of" from outside API

I am trying make online cantor. i need to get table with currency value from outside API, exactly from that page : http://api.nbp.pl/api/exchangerates/tables/A?format=json
I want to get answer in Currency class. Could someone help me with that task ?
#Service
public class CurrentFromNBPImpl implements CurrentFromNBP {
#Override
public Currency getValueOfCurrency(String currencyCode) throws WrongCurrencyCode {
Currency currency = null;
try {
URL url = new URL("http://api.nbp.pl/api/exchangerates/tables/A?format=json");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setRequestProperty("Content-Type", "application/json");
if (connection.getResponseCode() == 404)
throw new WrongCurrencyCode(currencyCode);
InputStreamReader inputStreamReader = new InputStreamReader(connection.getInputStream());
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String jsonOutput = bufferedReader.readLine();
connection.disconnect();
ObjectMapper objectMapper = new ObjectMapper();
Currency list = objectMapper.readValue(jsonOutput, Currency.class);
System.out.println(list);
} catch (IOException e) {
e.printStackTrace();
}
assert false;
return currency;
}
}
#Data
public class Currency {
#JsonProperty("table")
private String table;
#JsonProperty("no")
private String no;
#JsonProperty("effectiveDate")
private String effectiveDate;
#JsonProperty("rates")
private List<Rate> rates = null;
}
#Data
public class Rate {
#JsonProperty("currency")
private String currency;
#JsonProperty("code")
private String code;
#JsonProperty("mid")
private Double mid;
}
log:
com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of com.kolej.bartosz.challenge.domain.Currency out of START_ARRAY token
at [Source: (String)"[{"table":"A","no":"062/A/NBP/2019","effectiveDate":"2019-03-28","rates":[{"currency":"bat (Tajlandia)","code":"THB","mid":0.1202},{"currency":"dolar amerykański","code":"USD","mid":3.8202},{"currency":"dolar australijski","code":"AUD","mid":2.7098},{"currency":"dolar Hongkongu","code":"HKD","mid":0.4867},{"currency":"dolar kanadyjski","code":"CAD","mid":2.8461},{"currency":"dolar nowozelandzki","code":"NZD","mid":2.6006},{"currency":"dolar singapurski","code":"SGD","mid":2.8179},{"currency":"eu"[truncated 1616 chars]; line: 1, column: 1]

Your json object that you want to deserialize is a jsonArray. You need to deserialize into a list of Currency, instead of a Currency.

You can try this
ArrayList<Currency> list = new ArrayList<>();
list = objectMapper.readValue(data, new TypeReference<ArrayList<Currency>>() {});

Convert JSON string to json objects

I have a json string returning:
[{"TRAIN_JOURNEY_STAFF[],"ID":15,"EMAIL_ADDRESS":"jk#connectedrail.com","PASSWORD":"test","FIRST_NAME":"Joe","LAST_NAME":"Kevin","DATE_OF_BIRTH":"1996-04-20T00:00:00","GENDER":"Male","STAFF_ROLE":"Conductor","PHOTO":null},{new record..}]
There are several records here, I can't find a way to convert this json string to individual objects. I'm using the following to read in the data:
StringBuffer response;
try (BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()))) {
String inputLine;
response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
}
System.out.print(response.toString());
}
I've tried the simple json libary but the parser mixes up the string, Which is not ideal as I need to output the data to rows object by object to jtables.
Any help would be appreciated.
Solved it with the below with GSON. Many thanks everyone!
JsonElement jelement = new JsonParser().parse(response.toString());
JsonArray jarray = jelement.getAsJsonArray();
JsonObject jobject = jarray.get(0).getAsJsonObject();
System.out.println(jobject.get("FIRST_NAME"));

You can use something like this:
public class ObjectSerializer {
private static ObjectMapper objectMapper;
#Autowired
public ObjectSerializer(ObjectMapper objectMapper) {
ObjectSerializer.objectMapper = objectMapper;
}
public static <T> T getObject(Object obj, Class<T> class1) {
String jsonObj = "";
T userDto = null;
try {
jsonObj = objectMapper.writeValueAsString(obj);
userDto = (T) objectMapper.readValue(jsonObj, class1);
System.out.println(jsonObj);
} catch (JsonProcessingException jpe) {
} catch (IOException e) {
e.printStackTrace();
}
return userDto;
}
Pass your JSON Object to this method alogn with class name and it will set the JSON data to that respective class.
Note:
Class must have the same variables as in the JSON that you want to map with it.

Using org.json library:
JSONObject jsonObj = new JSONObject("{\"phonetype\":\"N95\",\"cat\":\"WP\"}");
see this

You can use Jackson to convert JSON to an object.Include the dependency :
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.6.3</version>
</dependency>
Then make a POJO class to store the JSON .The pojo class should reflect the json string structure and should have appropriate fields to map the values(Here in sample code Staff.class is a pojo class).Then, by using ObjectMapper class you can convert the JSON string to a java object as follows :
StringBuffer response;
try (BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()))) {
String inputLine;
response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
}
System.out.print(response.toString());
ObjectMapper mapper = new ObjectMapper();
//JSON from file to Object
Staff obj = mapper.readValue(new File("c:\\file.json"), Staff.class);
//JSON from String to Object
Staff obj = mapper.readValue(response.toString(), Staff.class);
Another simple method to read a JSON string and convert it into an object is :
JSON String:
{
"lastName":"Smith",
"address":{
"streetAddress":"21 2nd Street",
"city":"New York",
"state":"NY",
"postalCode":10021
},
"age":25,
"phoneNumbers":[
{
"type":"home", "number":"212 555-1234"
},
{
"type":"fax", "number":"212 555-1234"
}
],
"firstName":"John"
}
public class JSONReadExample
{
public static void main(String[] args) throws Exception
{
// parsing file "JSONExample.json"
Object obj = new JSONParser().parse(new FileReader("JSONExample.json"));
// typecasting obj to JSONObject
JSONObject jo = (JSONObject) obj;
// getting firstName and lastName
String firstName = (String) jo.get("firstName");
String lastName = (String) jo.get("lastName");
System.out.println(firstName);
System.out.println(lastName);
// getting age
long age = (long) jo.get("age");
System.out.println(age);
// getting address
Map address = ((Map)jo.get("address"));
// iterating address Map
Iterator<Map.Entry> itr1 = address.entrySet().iterator();
while (itr1.hasNext()) {
Map.Entry pair = itr1.next();
System.out.println(pair.getKey() + " : " + pair.getValue());
}
// getting phoneNumbers
JSONArray ja = (JSONArray) jo.get("phoneNumbers");
// iterating phoneNumbers
Iterator itr2 = ja.iterator();
while (itr2.hasNext())
{
itr1 = ((Map) itr2.next()).entrySet().iterator();
while (itr1.hasNext()) {
Map.Entry pair = itr1.next();
System.out.println(pair.getKey() + " : " + pair.getValue());
}
}
}
}
For reference:
https://www.geeksforgeeks.org/parse-json-java/
https://www.mkyong.com/java/jackson-2-convert-java-object-to-from-json/

What you have basically is this :
[
{
"TRAIN_JOURNEY_STAFF":[
],
"ID":15,
"EMAIL_ADDRESS":"jk#connectedrail.com",
"PASSWORD":"test",
"FIRST_NAME":"Joe",
"LAST_NAME":"Kevin",
"DATE_OF_BIRTH":"1996-04-20T00:00:00",
"GENDER":"Male",
"STAFF_ROLE":"Conductor",
"PHOTO":null
},
{
}
]
You can use JSON constructor to serialize this array to an Array of JSONObjects.
Try looking for JSONObject and JSONArray classes in Java.
The constructor basically takes the stringified JSON (which you already have).

Can't read json file

Here's my method where im reading json file.
private void LoadTabaksFromJson() {
InputStream raw = mContext.getResources().openRawResource(R.raw.tabaks);
Reader reader = new BufferedReader(new InputStreamReader(raw));
ListOfTabaks listOfTodos = new Gson().fromJson(reader, ListOfTabaks.class);
List<Tabak> todoList = listOfTodos.getTodoArrayList();
for (Tabak item: todoList){
mDataBase.insert(TabakTable.NAME,null,getContentValues(item));
}
}
public class ListOfTabaks {
protected ArrayList<Tabak> tabakArrayList;
public ArrayList<Tabak> getTodoArrayList(){
return tabakArrayList;
}
}
And Exeption
Caused by: java.lang.NullPointerException: Attempt to invoke interface
method 'java.util.Iterator java.util.List.iterator()' on a null object
reference
at
com.hookah.roma.hookahmix.TabakLab.LoadTabaksFromJson(TabakLab.java:61)
at com.hookah.roma.hookahmix.TabakLab.(TabakLab.java:32)
at com.hookah.roma.hookahmix.TabakLab.get(TabakLab.java:37)
at
com.hookah.roma.hookahmix.TabakListFragment.updateUI(TabakListFragment.java:38)
at
com.hookah.roma.hookahmix.TabakListFragment.onCreateView(TabakListFragment.java:32)
at
android.support.v4.app.Fragment.performCreateView(Fragment.java:2184)
at
android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1298)
at
android.support.v4.app.FragmentManagerImpl.moveFragmentsToInvisible(FragmentManager.java:2323)
at
android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2136)
And json file :
{
"tabaksArrayList":[
{
"name":"Абрикос",
"description":"Со вкусом Абрикоса",
"rating":"4.1",
"favourite":"1",
"family":"Al fakher"
},
{
"name":"Ананас",
"description":"Со вкусом Ананаса",
"rating":"4.1",
"favourite":"1",
"family":"Al fakher"
},
{
"name":"Апельсин",
"description":"Со вкусом Апельсина",
"rating":"4.1",
"favourite":"1",
"family":"Al fakher"
},
{
"name":"Апельсин с мятой",
"description":"Со вкусом Апельсина с мятой",
"rating":"4.1",
"favourite":"1",
"family":"Al fakher"
},

It looks like your json schema issue, i'm guessing listOfTodos return null. You can refer to this to generate your schema.
But sometimes that tools can make us confuse so i tried to create your schema manually like this:
TabakRoot.java
public class TabakRoot {
#SerializedName("tabaksArrayList")
private List<TabakItem> tabakItem = null;
public List<TabakItem> getTabakItem() {
return tabakItem;
}}
TabakItem.java
public class TabakItem {
#SerializedName("family")
#Expose
private String tabakFamily;
public String getTabakFamily() {
return tabakFamily;
}}
finally
TabakRoot listOfTodos = new Gson().fromJson(reader, TabakRoot.class);
List<TabakItem> todoList = listOfTodos.getTabakItem();

Looks like you are not initialising your ArrayList, try changing:
protected ArrayList<Tabak> tabakArrayList;
for:
protected ArrayList<Tabak> tabakArrayList = new ArrayList<>();

Please put your json file in assets folder
use AsyncTask to protect from ANR like situtation
onBackground(){
String json = null;
try {
InputStream stream = activity.getAssets().open("ur_json_file_in_assets_folder.json");
int size = stream.available();
byte[] buffer = new byte[size];
stream.read(buffer);
stream.close();
json = new String(buffer, "UTF-8");
} catch (IOException e) {
e.printStackTrace();
return null;
}
return json;
}
then parse in
onPostExecute(String str){
JsonObject object = new JsonObject(str);
JsonArray arr = object.getJsonArray("tabaksArrayList");
...}
more details at ParseJsonFileAsync.java

You're not initialising tabakArrayList, add a constructor to your ListOfTabaks as following
public ListOfTabaks{
tabakArrayList = new ArrayList<>();
}
and you should be fine

Pass values from javascript to Servlet [duplicate]

This question already has answers here:
How should I use servlets and Ajax?
(7 answers)
Closed 6 years ago.
I'm new bee working on passing below data from jquery to Servlet. Below are my files
javascript:
<script type="text/javascript">
function getData(tableName)
{
var tableId =tableName+"Table";
jsonObj = [];
$(\'#' + tableId + '\').find(\'tbody>tr\').each(function (i) {
var $tds = $(this).find('td'), setvilId = $tds.eq(1).text(),setvilNotes = $tds.eq(8).text();
item = {};
item["id"] = setvilId;
item["notes"] = setvilNotes;
jsonObj.push(item);
});
console.log(jsonObj);
var jsonString =JSON.stringify(jsonObj);
request(jsonString);
};
</script>
<script type=\"text/javascript\">
function updateNotes () {
var editable = true;
var editables = $('td[id*=notestd], td[id*=eta]');
editables.attr('contentEditable', editable);
}
function request(jsonString) {
$.ajax({
url: "/updatesetvil",
type: "POST",
data: jsonString,
dataType: "text",
success: function(){
alert(\"success\");
},
error:function(){
alert(\"failure\");
}
});
};
</script>
Servlet:
public class UpdateSetvil extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = 1L;
List<SetvilJsonAttributes> setvilAttrs = new LinkedList<SetvilJsonAttributes>();
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
out.println("Inside servlet");
// 1. get received JSON data from request
BufferedReader br = new BufferedReader(new InputStreamReader(request.getInputStream()));
String json = "";
if(br != null){
json = br.readLine();
}
System.out.println(json.toString()); // [{"id":"","notes":""},{"id":"18001","notes":"fdafd"},{"id":"8350","notes":"daggda"},{"id":"8056","notes":"gfdagdfa"}]
// 2. initiate jackson mapper
ObjectMapper mapper = new ObjectMapper();
// 3. Convert received JSON to Class
SetvilJsonAttributes setvilatt = mapper.readValue(json, SetvilJsonAttributes.class);
// 4. Set response type to JSON
response.setContentType("application/json");
setvilAttrs.add(setvilatt);
for (int i=0;i< setvilatt.size(); i++) {
System.out.println(setvilatt.get(i).getId());
}
}
private class SetvilJsonAttributes {
Integer id;
String notes;
String eta;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getNotes() {
return notes;
}
public void setNotes(String notes) {
this.notes = notes;
}
public String getEta() {
return eta;
}
public void setEta(String eta) {
this.eta = eta;
}
}
}
Error: java.io.IOException: Error parsing JSON request string
I kindly request anyone to help me on this.I have been stuck and unable to proceed further.

try this,
$.ajax({
url: "/updatesetvil",
type: "POST",
// The key needs to match your method's input parameter (case-sensitive).
data: { jsonString: jsonString},
contentType: "application/json; charset=utf-8"
dataType: "text",
success: function(data){
alert(\"success\"+data);
},
error:function(){
alert(\"failure\"+data);
}
});

Suggestion
If you are getting issues while parsing a JSON string then I can help you to parse the JSON string into Java object using GSON library as illustrated in below sample code.
Please note id should be String otherwise it will result into NumberFormatException for empty id values.
Sample code:
class SetvilJsonAttributes {
private String id;
private String notes;
// getter & setter
}
String jsonString="[{\"id\":\"\",\"notes\":\"\"},{\"id\":\"18001\",\"notes\":\"fdafd\"},{\"id\":\"8350\",\"notes\":\"daggda\"},{\"id\":\"8056\",\"notes\":\"gfdagdfa\"}]";
Type type = new TypeToken<ArrayList<SetvilJsonAttributes>>() {}.getType();
ArrayList<SetvilJsonAttributes> data = new Gson().fromJson(jsonString,type);
System.out.println(new GsonBuilder().setPrettyPrinting().create().toJson(data));
output:
[
{
"id": "",
"notes": ""
},
{
"id": "18001",
"notes": "fdafd"
},
{
"id": "8350",
"notes": "daggda"
},
{
"id": "8056",
"notes": "gfdagdfa"
}
]
If you don't want to change the type of id field then you can try with JsonDeserializer to deserializer it as per your need.
Please have a look at my another posts here and here for JsonDeserializer.

See these three lines:
System.out.println(json.toString()); // [{"id":"","notes":""},{"id":"18001","notes":"fdafd"},{"id":"8350","notes":"daggda"},{"id":"8056","notes":"gfdagdfa"}]
ObjectMapper mapper = new ObjectMapper();
SetvilJsonAttributes setvilatt = mapper.readValue(json, SetvilJsonAttributes.class);
The value of json is a JSON array. But, then you map it to SetvilJsonAttributes, which does not support JSON array. You can convert this json to a List of SetvilJsonAttributes using:
ObjectMapper mapper = new ObjectMapper();
ArrayList<SetvilJsonAttributes> setvilatt = mapper.readValue(json, new TypeReference<ArrayList<SetvilJsonAttributes>>(){});

I have used JSONArray and it worked out
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
out.println("Inside servlet");
Connection connector = MysqlConnector.getDBCon();
StringBuffer sb = new StringBuffer();
String line = null;
try {
BufferedReader reader = request.getReader();
while ((line = reader.readLine()) != null) {
sb.append(line);
}
json = sb.toString();
} catch (Exception e) {
System.out.println("Exception while reading JSON String");
e.printStackTrace();
}
System.out.println("String is " + json);
try {
JSONArray inputArray = new JSONArray(json);
for (int i=0; i < inputArray.length(); i++) {
JSONObject c = inputArray.getJSONObject(i);
String id = c.getString("id");
String notes = c.getString("notes");
System.out.println(id + "--> " + notes);
} catch (JSONException e) {
// crash and burn
System.out.println("Parse exeception for array");
e.printStackTrace();
}
}