Your browser does not seem to support JavaScript. As a result, your viewing experience will be diminished, and you may not be able to execute some actions.

Please download a browser that supports JavaScript, or enable it if it's disabled (i.e. NoScript).

Why is the method of creating a copy of the class?

N
Nykeriab last edited by
```
...... 
PersonsExtracter personsExtracter = new PersonsExtracter().invoke(); 
if (personsExtracter.wasError()) { 
    System.out.println("App was stopped"); 
    return;
}
......
```
You could explain in two words why you need a method. invoke() at the end of the facility new PersonsExtracter().invoke() or give a link where you could read it. Google, I didn't find a clear answer or I didn't ask the right question in the search. The right question is the right answer. To be honest, I haven't seen the code design so that the method is written at the end of the facility.
Reply Quote 0
1 Reply Last reply
R
Rossere last edited by
It's just that the method is being challenged. invoke() Class PersonsExtracterin which something is done, there may be some sort of thing to initiate something, design and other, and a reference to the same object (mostly).
And since the method is not static, it can only be triggered by the creation of a copy that actually happens.
I think it's a banal emulsion of the designer's work, that's instead of the method.
```
class PersonsExtracter {
    public PersonsExtracter invoke() {
         // doing smth
        return this;
    }
}
```
It was possible to make a designer with the same job.
```
class PersonsExtracter {
    PersonsExtracter() {
        // doing smth
    }
}
```
And for what reason the author decided to do so, or otherwise, you could ask him.
Reply Quote 0
1 Reply Last reply

java 62922

2
Posts

0
Views

Suggested Topics

Good tone in the use of class members when calling class methods
Software Programming • c++ classes methodes parameters inculation • • Demir

2

0
Votes

2
Posts

0
Views

S

If the functions of the class members, their friends or derivative classes are often use the same code, then the code should be turned down. A separate function. function...). If this functionality is necessary only for implementation this class and its derivative classes should then be use it as a protected member.If you've created the right abstraction, and you've done well, you know, You should think about it. Preservation of the invariant, first and foremost of all construction Class should initiate its non-initialized members (what You don't.If you encapsulated data as protected members, you're sure. Accept that there will be heirs for whom these are necessary. members.To determine how best to write what methods should be to have each of the classes (and to avoid the spread of the class code), you must clearly represent the challenge. performs every class in a hierarchy. Abstract base class with these methods, and as long as you know it Only you, of course, no one but you will be able to give a full answer to the good tone. ♪ ♪
T

It is not possible to use the class method from the inside of another method
Software Programming • javascript html dom • • tahishae

2

0
Votes

2
Posts

0
Views

D

const game = new TicTacToe();startGame.addEventListener('click', game.start, {capture: true});/Field create.addEventListener('click', this.move, {capture: true});These tricks are called the loss of context.You need to read it. https://ru.stackoverflow.com/a/536020/2659 @Grundy, and continue to take contexts closer.Operating code:const field = document.querySelector('.wrapper'), startGame = document.querySelector('#startGame'); class TicTacToe { constructor() { this._started = false; this._ended = false; this._count = 0; } start(ev) { ev.stopPropagation(); this._started = true; const createField = document.createElement('table'); createField.classList.add('tic-tac-toe'); for (let i = 0; i < 3; i++) { const tr = document.createElement('tr'); for (let i = 0; i < 3; i++) { const td = document.createElement('td'); tr.appendChild(td); } createField.appendChild(tr); } createField.querySelectorAll('td').forEach((el, i) => { el.classList.add(tdField-${i + 1}); }); createField.addEventListener('click', this.move.bind(this), { capture: true }); // ! Вешаю event listener на поле field.innerHTML = ''; field.appendChild(createField); this.move(ev); // !!! Если просто обратиться к методу move, то выдаёт ошибку } move(ev) { ev.stopPropagation(); this._count++; this._checkCount(); if (this.ended) { this._end(); } else { this._checkClassList(ev); } console.log(3); // !! При клике должно выводиться 3, но не выводится } _end() { alert('finita'); } _checkCount() { if (this.count >= 9) { this._ended = true; } } _checkClassList(evCb) { console.log(evCb.target) } get started() { return this._started; } get count() { return this._count; } get ended() { return this._ended; } } const game = new TicTacToe(); startGame.addEventListener('click', game.start.bind(game), { capture: true });.wrapper { position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); } .tic-tac-toe { border-collapse: collapse; } .tic-tac-toe td { border: 2px solid rgb(26, 26, 26); width: 100px; height: 100px; text-align: center; cursor: pointer; }<div class="wrapper"> <button id="startGame">Начать!</button> </div>
E

How to create a copy of the object and then remove only a copy - GDScript
Software Programming • godot gdscript • • elysha

2

0
Votes

2
Posts

0
Views

R

You've got all the copies of one scruple, naturally, they'll get away in sync and all at once. Try to assign every unique number to them and add the interval between the removal of different unique numbers.
C

How or is it possible to contact the object of another class at all without creating a copy of this class a new directive inside this class?
Software Programming • php op pdo • • charlenef

2

0
Votes

2
Posts

0
Views

K

You can use a pattern synthlon. So we create a static $instance inside the DatabaseConnection as a reference to a copy of the current class and add a ghetter to this attribute, which checks whether it is empty, if not empty, it returns it, no, creates a new facility DatabaseConnection and returns. class DatabaseConnection { private static $instance = null; private $host = 'localhost'; private $databaseName = 'grossbux'; private $userName = 'root'; private $password = ''; public $dsn, $opt, $pdo; function __construct() { $this->dsn = "mysql:host=$this->host;dbname=$this->databaseName"; $this->opt = [ PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC, PDO::ATTR_EMULATE_PREPARES => false, ]; try { $this->pdo = new PDO($this->dsn , $this->userName, $this->password, $this->opt); } catch(PDOException $e) { include 'php/stubs/db_conn_error.php'; } } public static function getInstance() { return self::$instance===null ? self::$instance = new self() : self::$instance; } } somewhere else in the program.$conn = DatabaseConnection::getInstance(); In this case, a copy of the DatabaseConnection class will always be one.
N

Access to Tomcat Manager
Software Programming • java tomcat • • Nykeriab

2

0
Votes

2
Posts

0
Views

S

You have a mistake in the name of the user. For manager♪ manager-guiinstead admin_gui♪ admin-gui♪ It's a tyre.
C

Is it correct to create a class with aesthetic methods to connect to a MySQL database?
Software Programming • php mysql mysqli • • Cleofas

2

0
Votes

2
Posts

0
Views

What you're trying to do I suppose is to implement a singleton pattern for the connection, in which case it should be:class ConexionBD { private static $instance; private static function conectar() { $conn = new mysqli( 'localhost', 'root', 'pass', 'nombreBD'); if ($conn->connect_error) { die('Error de Conexión ('.$conn->connect_errno.') '.$conn->connect_error); } return $conn; } public static function getConexion(){ if(!self::$instance) { self::$instance = self::conectar(); } return self::$instance; } } And use the connection in other classes like$conn = ConexionBD::getConexion(); That way you'd make sure that by calling many times ConexionBD::getConexion() always give you the same connection back, and so you can open a transaction in one method and commit into another method. On the other hand, if you really wanted to make sure the connection was always the same, you'd have to overwrite the connection. magic_method __clone so he wouldn't let the connection clone:public function __clone() { throw new Exception("No se puede clonar esta clase"); } And, by the way, make sure that the class builder is private for anyone to do, without wanting new ConexionBD()private function __contruct() {} Now, using the singleton pattern in PHP is considered an antipatron. For example if you want to do unit tests, each test would use the same connection and would be influenced by the operations that the previous test has performed. That contradicts the very concept of a unitary text.There are no connection pools in PHP (in the sense that PHP sticks to a permanently open service that maintains several connections and persists between requests) but that each client who enters will create their own connection and this will be automatically closed when the request's life. In this sense a kind of pooling occurs as it says https://es.stackoverflow.com/users/324/gbianchi , but it is not a persistent pool as it occurs in a Python or Node.js app. PHP recreates the app on each request.You don't have to make two customers who enter your app use the same connection, and that's actually good, because a client could open a transaction and another client invoke a method running a COMMIT. It would be pretty bad for a third party to do COMMIT to your transaction when you're inserting bulk records. Likewise, it is not really so terrible to urge a new connection in each controller. Again, as he said https://es.stackoverflow.com/users/324/gbianchi , this would allow you to handle two or more connections in the same controller and (rebused case) use a connection to read from one table and another to insert into another table.$resultado = $conn1->query('SELECT nombre, apellido from clientes where region=1'); $stmt = $conn2->prepare("INSERT into clientes_region1 (nombre,apellido) VALUES (?,?)"); $stmt->bind_param('ss', $nombre, $apellido); while ($row = $resultado->fetch_array()){ $nombre = $row['nombre']; $apellido = $row['apellido']; $stmt->execute(); } By the principle of sole responsibility, the controller should open its connection (and optionally close it) without relying on a global connection. If you need two methods of the same controller to use the same connection, then use the connection as a variable of the class when making __construct of the controller. class Ejemplo { private $conexion; public function __construct() { $this->conexión = new mysqli(...); } } And if you need a class to pass its connection instance to another class, do it with injection of dependencies: instance the second class bypassing its builder the connection instance you already have. class Padre { private $conexion; private $hijo; public function __construct() { $this->conexión = new mysqli(...); $this->hijo = new Hijo($this->conexion); } } That way, if you want to do class unit tests HijoYou create the connection in the test, class instances, you run the test, you close the connection.EDIT Is it optional to close the connection?Short answer: yes, it is optional. The connection will be closed when the request life cycle ends. PEEEERO... There are cases of edge.Suppose your application has very long requests. For example, read from a table of 500,000 records, put them in an array, process them, save them in a file, upload that file to a remote server, etc (I predict that your memory parameters and execution time limit support this) and that process lasts in 10 minutes.In this case you need to have the connection open just to read those 500,000 chart records. The rest of the 10 minutes remains open only because the request is not finished. The connection is "taken" and the database only supports a limited number of simultaneous connections (this is configurable, but still is a finite number). For that case of use it would be appropriate to close the connection just by bringing the data from the table to free connections from the database and thus not block other users.
Creation of a copy of the last class from a copy of the advance class
Software Programming • c sharp legacy • • jeanid

2

0
Votes

2
Posts

0
Views

J

Well, problems are possible, of course.Class field T2 may have the same names with classes T1 (field closure). public class SubjectA : Basis { public new decimal whatever { get; set; } } It'll lead to an exception.Second, class properties T1 I don't know if there's a netter at all.public class Basis { public string something { get; } = "something"; public int whatever { get; set; } } or may be declared private: public string something { get; private set; } Thirdly, the base type may have a static characteristic that will lead to a breakdown of your method:public class Basis { public string something { get; set; } public int whatever { get; set; } public static int gotcha { get; set; } } Then, apart from the properties of the base class, there may be some important fields that you do not take into account.Well, for the last time, setting the field value for sufficiently complex objects may require additional logic to maintain your class invaders. That's why I would only use this method for quite simple DTO classes.I'd rewrite a method like this:public static T2 UpgradeClass<T1, T2>(T1 basis) where T1 : new() where T2 : T1, new() { T2 upgrade = new T2(); for (Type t = basis.GetType(); t != null; t = t.BaseType) foreach (PropertyInfo p in t.GetProperties( BindingFlags.Instance | BindingFlags.Public)) p.SetValue(upgrade, p.GetValue(basis)); return upgrade; } In that way, the method is still not good.This solves the problem of conflicts of names and statistical properties, but does not solve the problem of properties without a netter/with a privatized as well as the problem of fields. Privacy netter (and ghetter) possible I'd call it a reflexia, too, but I don't think it's right: if the class seed is closed, it might be a non-trivial logic that can't be called at an arbitrary moment, which means it's not worth cutting it outside.
J

I insert DNI instead of current user email
Software Programming • java jsf primfac languagees • • jules

2

0
Votes

2
Posts

0
Views

M

In Reader.java in the switch are not specified the corresponding break and when you find a match you will execute all the other lines.
R

Androids, how do we make the view of the working table not updated at a time interval and at 12:00 a day?
Software Programming • java android widgets • • Raziyah00

2

0
Votes

2
Posts

0
Views

AlarmManager can be installed. At the first entrance, you'll figure out what's left until 12:00 and launch AlarmManager. When AlarmManager works again, calculate how much time is left until 12:00 and launch it again. I hope you understand the logic. https://developer.android.com/reference/android/app/AlarmManager
S

How quickly do you set up your java server?
Software Programming • java multi point sirver • • simrah

2

0
Votes

2
Posts

0
Views

O

Sometimes you have to make it easy. HTTP java server who responds to GET and POST by MySql database and don't waste time for turning Tomcat or he's such a big guy.On the basis of the proposed abstract classes, a very effective server (each request is processed in a separate flow) has been established at some time ago. https://en.wikipedia.org/wiki/Bidding that hit all the speed records on the e-trade markets with context advertising. I want to share how to do this:First, we need to download the jar library on this. https://cloud.mail.ru/public/2w9F/2eikiPvVF and include it in its draft. Then create a class main and inherit it from YaaServer Classimport com.yaa.server.YaaServer; public class MyServer extends YaaServer { public static void main(String[] args) { // TODO Auto-generated method stub } } Abstract class YaaServer It will require the generation of several methods and designers. Let him do it:import java.io.IOException; import java.sql.Connection; import com.yaa.server.YaaServer; import com.yaa.server.YaaServlet; public class MyServer extends YaaServer { public MyServer(int port) throws IOException { super(port); // TODO Auto-generated constructor stub } public static void main(String[] args) { // TODO Auto-generated method stub } @Override protected Connection getConnection() { // TODO Auto-generated method stub return null; } @Override protected Class<YaaServlet> getServletClass(int arg0) { // TODO Auto-generated method stub return null; } @Override protected String getServletContext(int arg0) { // TODO Auto-generated method stub return null; } @Override protected int howManyServlets() { // TODO Auto-generated method stub return 0; } @Override protected boolean isLog() { // TODO Auto-generated method stub return false; } @Override protected String setServerName() { // TODO Auto-generated method stub return null; } } There's a little left. Injection main new MyServer(8080).start(); and received: public static void main(String[] args) { try { new MyServer(8080).start(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } Our server is almost ready. Give him a name on the method. setServerName() protected String setServerName() { return "My First javaServer"; } And let's go. We'll see a message in the console:My First javaServer Server started. Listening for connections on port : 8080 ... Clearly, your server is listening to port 8080 on your computer. Just a little bit left. We need to fill this server with HTTP queries. Create a GET request processor who processes user identity and age. In the address line of the browser, this request would look like:http://localhost:8080/myserver?name=Иван&age=19 Now browser's gonna get rid of this request. 404 Not Found♪ Let's see what he'll do later. So...1. In method howManyServlets() ♪ Number of processors♪ return 1; 2. in method getServletContext change return protected String getServletContext(int i) { return new String[] { "/myserver" }[i]; } This means that our processor will be treated in context /myserverLook at the line of the request from the browser;3. Modify getServletClass as follows: protected Class<YaaServlet> getServletClass(int i) { return new Class[] { Myservlet.class }[i]; } That's what we say in context /myserver I'll be a processor in a class with a name. Myservlet♪Eclipse (Beep) ide) He needs to create this class. Create and follow him. YaaServlet♪ Permit the generation of abstract methods and design and receive:import java.sql.Connection; import java.util.Map; import com.yaa.server.YaaServlet; public class Myservlet extends YaaServlet { public Myservlet(Connection conn, Map<String, String> get_request, String post_request) { super(conn, get_request, post_request); // TODO Auto-generated constructor stub } @Override protected String getResponcse() { // TODO Auto-generated method stub return null; } } conn - it's a base conjector. MySqlWe haven't used it yet;get_request ♪ GET parameters HashMap collections;post_request - line POST Request.The answer to the GET has to be: protected String getResponcse() { if (get_request != null) return "Привет " + get_request.get("name") + "! \nТвой возраст " + get_request.get("age") + " лет."; return null; } Now reboot the server and repeat our request from the browser. If we did the right thing, we'll see in the browser:Привет Иван! Твой возраст 19 лет. Processing POST I suggest you do it yourself. In this example, we didn't connect the database. To do so in the method getConnection() server to connect the driver. About that. return conn = DriverManager.getConnection("jdbc:mysql://...");By the way, the processor doesn't have to close the base. conn.close()♪
B

java: search in txt and printed line and the following
Software Programming • java • • Burma

2

0
Votes

2
Posts

0
Views

Z

if (ln.contains(wanted1)) { // ln.indexOf(1, length) System.out.println("строка_1 " + ln); if (lines.indexOf(ln) == lines.size() - 1) { return; } System.out.println("строка_2 " + lines.get(lines.indexOf(ln) + 1)); }
D

Stream filter.findfirst
Software Programming • java filter data flows • • Duquan

2

0
Votes

2
Posts

0
Views

C

The question doesn't make it very clear what I want, but I'll assume:Stream<String> stringStream = Files.lines(path, StandardCharsets.UTF_8); Optional<String> firstStr = stringStream.filter(i -> i.contains("12")).findFirst(); firstStr.ifPresent(System.out::println);
E

Difference between a class builder to define a method that creates class objects
Software Programming • java poo • • emerson

2

0
Votes

2
Posts

0
Views

D

In Java always. You use a builder to start a class, and if it is the default builder (which basically does nothing).public class Foo{ public static Foo getInstance(){ return new Foo(); } } In this trivial example both methods are seen, as seen in the "type manufacturer" builder, a builder is also used.Creating a manufacturing method can make sense if I want to control the context in which objects are created, it is used for example (but not exclusively) in "Singletons", classes that never have more than an object of its kind installed at the same time:public class Foo(){ private static final Foo foo = new Foo(); public static Foo getSingleton(){ return foo; } private Foo(){} } An important case for using manufacturing methods can be when I have injected two objects with bilateral references (foo.bar and bar.foo), in this case the method manufactures me guarantees that the object is not publicly accessible before all the methods I have to call the object until it is ready for use, for example a method init() to initialize.Example:We have one. Application and one Context. Next code No. it's going to work, because I can't start an object before I have the other one installed. :public class Application(){ private Context context=null; private Application(Context context){ this.context=context; } public Context getContext(){ return context; } } public class Context{ private Application app = null; private Context(Application app){ this.app=app; } public Application getApplication(){ return app; } } Then you have to change to use a manufacturing method like this:public class Application(){ private Context context=null; private Application(Context context){ this.context=context; } public Context getContext(){ return context; } } public class Context{ private Application app = null; private Context(){} public static Context getNewContext(){ Context context = new Context(); context.app=new Application(context); return context; } public Application getApplication(){ return app; } } Or vice versa. So I avoid publishing objects with lack of references.
How to create a layer of class
Software Programming • c sharp liabilities • • Bogopo

2

0
Votes

2
Posts

0
Views

S

Data value = new Data(); value.Name = 'Name 1'; List<Data> list = new List<Data>(); list.Add(value);
Configure for Eclipse show parameters name in auto-complete
Software Programming • java javafx ec languagelipse • • Alberto

2

0
Votes

2
Posts

0
Views

In the view Project Explorer expands your design and then expands the item JRE System Library. In it you will find an item called jfxrt. jar, right click and select the option Properties. This will open a dialog window of the properties of this jar.In jenala look for the item Javadoc Location. Mark the option Javadoc URL and place: https://docs.oracle.com/javafx/2/api/. Click Apply and you can see the javadoc of methods and classes.

Why is the method of creating a copy of the class?

Suggested Topics

Good tone in the use of class members when calling class methods Software Programming • c++ classes methodes parameters inculation • • Demir

It is not possible to use the class method from the inside of another method Software Programming • javascript html dom • • tahishae

How to create a copy of the object and then remove only a copy - GDScript Software Programming • godot gdscript • • elysha

How or is it possible to contact the object of another class at all without creating a copy of this class a new directive inside this class? Software Programming • php op pdo • • charlenef

Access to Tomcat Manager Software Programming • java tomcat • • Nykeriab

Is it correct to create a class with aesthetic methods to connect to a MySQL database? Software Programming • php mysql mysqli • • Cleofas

Creation of a copy of the last class from a copy of the advance class Software Programming • c sharp legacy • • jeanid

I insert DNI instead of current user email Software Programming • java jsf primfac languagees • • jules

Androids, how do we make the view of the working table not updated at a time interval and at 12:00 a day? Software Programming • java android widgets • • Raziyah00

How quickly do you set up your java server? Software Programming • java multi point sirver • • simrah

java: search in txt and printed line and the following Software Programming • java • • Burma

Stream filter.findfirst Software Programming • java filter data flows • • Duquan

Difference between a class builder to define a method that creates class objects Software Programming • java poo • • emerson

How to create a layer of class Software Programming • c sharp liabilities • • Bogopo

Configure for Eclipse show parameters name in auto-complete Software Programming • java javafx ec languagelipse • • Alberto

Good tone in the use of class members when calling class methods
Software Programming • c++ classes methodes parameters inculation • • Demir

It is not possible to use the class method from the inside of another method
Software Programming • javascript html dom • • tahishae

How to create a copy of the object and then remove only a copy - GDScript
Software Programming • godot gdscript • • elysha

How or is it possible to contact the object of another class at all without creating a copy of this class a new directive inside this class?
Software Programming • php op pdo • • charlenef

Access to Tomcat Manager
Software Programming • java tomcat • • Nykeriab

Is it correct to create a class with aesthetic methods to connect to a MySQL database?
Software Programming • php mysql mysqli • • Cleofas

Creation of a copy of the last class from a copy of the advance class
Software Programming • c sharp legacy • • jeanid

I insert DNI instead of current user email
Software Programming • java jsf primfac languagees • • jules

Androids, how do we make the view of the working table not updated at a time interval and at 12:00 a day?
Software Programming • java android widgets • • Raziyah00

How quickly do you set up your java server?
Software Programming • java multi point sirver • • simrah

java: search in txt and printed line and the following
Software Programming • java • • Burma

Stream filter.findfirst
Software Programming • java filter data flows • • Duquan

Difference between a class builder to define a method that creates class objects
Software Programming • java poo • • emerson

How to create a layer of class
Software Programming • c sharp liabilities • • Bogopo

Configure for Eclipse show parameters name in auto-complete
Software Programming • java javafx ec languagelipse • • Alberto