Some java code examples

Instanciation d'un objet

ObjectMapper mapper = new ObjectMapper();
Point originOne = new Point(23, 94);

Affectation d'un objet :

Exemple 1 :

public CountryControlReason(Country country, ControlReasonCode reasonCode, LocalDate date) {
   this.country = country;
   this.reasonCode = reasonCode;
   this.date = date;
   this.countryId = country.getId();
}

Exemple 2 :

public LocalDateTime deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {`
   String date = p.getText();
   DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
   LocalDateTime formatDateTime = LocalDate.parse(date, formatter).atStartOfDay();

   return formatDateTime;
}

ArrayList :

List<String> items = new ArrayList<>();
items.add("A");
items.add("B");
items.add("C");
items.add("D");
items.add("E");

for(String item : items){
	`System.out.println(item);
}

HashMap :

Map<String, Integer> items = new HashMap<>();
items.put("A", 10);
items.put("B", 20);
items.put("C", 30);
items.put("D", 40);
items.put("E", 50);
items.put("F", 60);

for (Map.Entry<String, Integer> entry : items.entrySet()) {
	System.out.println("Item : " + entry.getKey() + " Count : " + entry.getValue());
}

Vector :

Vector<Integer> v = new Vector<Integer>(n);
for (int i = 1; i <= n; i++)
     v.add(i);

LinkedList & Iterator :

LinkedList<String> list=new LinkedList<String>();
list.add("Steve");
list.add("Carl");
list.add("Raj");

list.addFirst("Negan");
list.addLast("Rick");
list.add(2, "Glenn");

Iterator<String> iterator=list.iterator();`
while(iterator.hasNext()){
  System.out.println(iterator.next());
}

HashSet :

Set<String> daysOfWeek = new HashSet<>();
daysOfWeek.add("Monday");
daysOfWeek.add("Tuesday");
daysOfWeek.add("Wednesday");
daysOfWeek.add("Thursday");
daysOfWeek.add("Friday");
daysOfWeek.add("Saturday");
daysOfWeek.add("Sunday");
daysOfWeek.add("Monday");

For & If :

MethodInvocation on For & If statement

public static RegulationLicense fromString(String text) {
        for (RegulationLicense b : RegulationLicense.values()) {
            if (b.getDescription().equalsIgnoreCase(text)) {
                return b;
            }
        }
        return null;
}

Exceptions :

Exemples :

try {
   writeOnFileSystem(media, stream);
} catch (IOException e) {
   throw new TechnicalError("Couldn't write file " + filename);
}

try {
   claims = jwtService.parseToken(token);
} catch (JwtException ex) {
   log.info("Invalid token : "+ex.getMessage());
   return null;
}

try {
   return json.get("token").asText();
} catch (IOException | RestClientException e) {
   throw new TechnicalError("Unable to login to EcLabs", e);
}

Multiple function call

Authentication auth = SecurityContextHolder.getContext().getAuthentication().getToken();   

API Stream

Exemple 1 :

double tailleMoyenneDesHommes = employes
        .stream()
        .filter(e -> e.getGenre() == Genre.HOMME)
        .mapToInt(e -> e.getTaille())
        .average()
        .orElse(0);