JavaRush /جاوا بلاگ /Random-SD /جاوا ۾ ڊيزائن جا نمونا [حصو 2]

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28 February 2021
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جاوا ۾ ڊيزائن جا نمونا [حصو 2]

هيلو سڀ. منهنجي پراڻي موضوع ۾ مون مختصر طور تي هر نموني کي بيان ڪيو آهي، هن موضوع ۾ آئون تفصيل سان ڏيکارڻ جي ڪوشش ڪندس ته نمونن کي ڪيئن استعمال ڪجي.

پيدا ڪندڙ

سنگلٽن

وضاحت :

ھڪڙي طبقي جي ھڪڙي مثال جي ٺاھڻ کي محدود ڪري ٿو ۽ پنھنجي واحد اعتراض تائين رسائي فراهم ڪري ٿو. ڪلاس تعمير ڪندڙ خانگي آهي. طريقو getInstance()ڪلاس جو صرف هڪ مثال ٺاهي ٿو.

عمل درآمد:

class Singleton {
    private static Singleton instance = null;
    private Singleton() {}
    public static Singleton getInstance() {
        if (instance == null) {
            instance = new Singleton();
		}
        return instance;
    }
    public void setUp() {
        System.out.println("setUp");
    }
}

public class SingletonTest {//тест
    public static void main(String[] args){
        Singleton singelton = Singleton.getInstance();
        singelton.setUp();
    }
}

ڪارخانو

وضاحت :

استعمال ڪيو ويندو آھي جڏھن اسان وٽ ھڪڙو سپر ڪلاس آھي گھڻن ذيلي ڪلاسن سان ۽ ان پٽ جي بنياد تي اسان کي ھڪڙي ذيلي ڪلاس مان واپس ڪرڻ جي ضرورت آھي. طبقي کي خبر ناهي ته ان کي ڪهڙي قسم جو اعتراض پيدا ڪرڻ گهرجي. شيون ٺاهي رهيا آهن ايندڙ ڊيٽا جي بنياد تي.

عمل درآمد:

class Factory {
    public OS getCurrentOS(String inputos) {
        OS os = null;
        if (inputos.equals("windows")) {
            os = new windowsOS();
        } else if (inputos.equals("linux")) {
            os = new linuxOS();
        } else if (inputos.equals("mac")) {
            os = new macOS();
        }
        return os;
    }
}
interface OS {
    void getOS();
}
class windowsOS implements OS {
    public void getOS () {
        System.out.println("применить для виндовс");
    }
}
class linuxOS implements OS {
    public void getOS () {
        System.out.println("применить для линукс");
    }
}
class macOS implements OS {
    public void getOS () {
        System.out.println("применить для мак");
    }
}

public class FactoryTest {//тест
    public static void main(String[] args){
        String win = "linux";
        Factory factory = new Factory();
        OS os = factory.getCurrentOS(win);
        os.getOS();
    }
}

خلاصو ڪارخانو

وضاحت :

توهان کي ممڪن فيڪٽريز جي خاندان مان هڪ مخصوص فيڪٽري لاڳو ڪرڻ جي اجازت ڏئي ٿي. لاڳاپيل شين جو هڪ خاندان ٺاهي ٿو. وسعت ڏيڻ آسان.

عمل درآمد:

interface Lada {
    long getLadaPrice();
}
interface Ferrari {
    long getFerrariPrice();
}
interface Porshe {
    long getPorshePrice();
}
interface InteAbsFactory {
    Lada getLada();
    Ferrari getFerrari();
    Porshe getPorshe();
}
class UaLadaImpl implements Lada {// первая
    public long getLadaPrice() {
        return 1000;
    }
}
class UaFerrariImpl implements Ferrari {
    public long getFerrariPrice() {
        return 3000;
    }
}
class UaPorsheImpl implements Porshe {
    public long getPorshePrice() {
        return 2000;
    }
}
class UaCarPriceAbsFactory implements InteAbsFactory {
    public Lada getLada() {
        return new UaLadaImpl();
    }
    public Ferrari getFerrari() {
        return new UaFerrariImpl();
    }
    public Porshe getPorshe() {
        return new UaPorsheImpl();
    }
}// первая
class RuLadaImpl implements Lada {// вторая
    public long getLadaPrice() {
        return 10000;
    }
}
class RuFerrariImpl implements Ferrari {
    public long getFerrariPrice() {
        return 30000;
    }
}
class RuPorsheImpl implements Porshe {
    public long getPorshePrice() {
        return 20000;
    }
}
class RuCarPriceAbsFactory implements InteAbsFactory {
    public Lada getLada() {
        return new RuLadaImpl();
    }
    public Ferrari getFerrari() {
        return new RuFerrariImpl();
    }
    public Porshe getPorshe() {
        return new RuPorsheImpl();
    }
}// вторая

public class AbstractFactoryTest {//тест
    public static void main(String[] args) {
        String country = "UA";
        InteAbsFactory ifactory = null;
        if(country.equals("UA")) {
            ifactory = new UaCarPriceAbsFactory();
        } else if(country.equals("RU")) {
            ifactory = new RuCarPriceAbsFactory();
        }

        Lada lada = ifactory.getLada();
        System.out.println(lada.getLadaPrice());
    }
}

تعمير ڪندڙ

وضاحت :

سادي شيون استعمال ڪندي پيچيده اعتراض ٺاهڻ لاء استعمال ڪيو ويو. آهستي آهستي اهو هڪ ننڍي ۽ سادي شئي مان وڏي شئي ٺاهي ٿو. توهان کي حتمي پيداوار جي اندروني نمائندگي کي تبديل ڪرڻ جي اجازت ڏئي ٿي.

عمل درآمد:

class Car {
    public void buildBase() {
        print("Doing корпус");
    }
    public void buildWheels() {
        print("Ставим колесо");
    }
    public void buildEngine(Engine engine) {
        print("Ставим движок: " + engine.getEngineType());
    }
    private void print(String msg){
        System.out.println(msg);
    }
}
interface Engine {
    String getEngineType();
}
class OneEngine implements Engine {
    public String getEngineType() {
        return "Первый двигатель";
    }
}
class TwoEngine implements Engine {
    public String getEngineType() {
        return "Второй двигатель";
    }
}
abstract class Builder {
    protected Car car;
    public abstract Car buildCar();
}
class OneBuilderImpl extends Builder {
    public OneBuilderImpl(){
        car = new Car();
    }
    public Car buildCar() {
        car.buildBase();
        car.buildWheels();
        Engine engine = new OneEngine();
        car.buildEngine(engine);
        return car;
    }
}
class TwoBuilderImpl extends Builder {
    public TwoBuilderImpl(){
        car = new Car();
    }
    public Car buildCar() {
        car.buildBase();
        car.buildWheels();
        Engine engine = new OneEngine();
        car.buildEngine(engine);
        car.buildWheels();
        engine = new TwoEngine();
        car.buildEngine(engine);
        return car;
    }
}
class Build {
    private Builder builder;
    public Build(int i){
        if(i == 1) {
            builder = new OneBuilderImpl();
        } else if(i == 2) {
            builder = new TwoBuilderImpl();
        }
    }
    public Car buildCar(){
        return builder.buildCar();
    }
}

public class BuilderTest {//тест
    public static void main(String[] args) {
        Build build = new Build(1);
        build.buildCar();
    }
}

پروٽوٽائپ

وضاحت :

بهتر ڪارڪردگي سان هڪ نقلي اعتراض ٺاهڻ ۾ مدد ڪري ٿي، هڪ نئين ٺاهڻ جي بدران، موجوده اعتراض جي واپسي کلون ٺاهي وئي آهي. موجوده شئي کي ڪلون ڪري ٿو.

عمل درآمد:

interface Copyable {
    Copyable copy();
}
class ComplicatedObject implements Copyable {
    private Type type;
    public enum Type {
        ONE, TWO
    }
    public ComplicatedObject copy() {
        ComplicatedObject complicatedobject = new ComplicatedObject();
        return complicatedobject;
    }
    public void setType(Type type) {
        this.type = type;
    }
}

public class PrototypeTest {//тест
    public static void main(String[] args) {
        ComplicatedObject prototype = new ComplicatedObject();
        ComplicatedObject clone = prototype.copy();
        clone.setType(ComplicatedObject.Type.ONE);
    }
}

ساخت وارو

اڊاپٽر

وضاحت :

ھڪڙي نموني کي استعمال ڪندي، اسان ٻن غير مطابقت واري شين کي گڏ ڪري سگھون ٿا. ڪنورٽر ٻن غير مطابقت رکندڙ شين جي وچ ۾.

عمل درآمد:

class PBank {
	private int balance;
	public PBank() { balance = 100; }
	public void getBalance() {
		System.out.println("PBank balance = " + balance);
	}
}
class ABank {
	private int balance;
	public ABank() { balance = 200; }
	public void getBalance() {
		System.out.println("ABank balance = " + balance);
	}
}
class PBankAdapter extends PBank {
	private ABank abank;
	public PBankAdapter(ABank abank) {
		this.abank = abank;
	}
	public void getBalance() {
		abank.getBalance();
	}
}

public class AdapterTest {//тест
	public static void main(String[] args) {
		PBank pbank = new PBank();
		pbank.getBalance();
		PBankAdapter abank = new PBankAdapter(new ABank());
		abank.getBalance();
	}
}

جامع

وضاحت :

ھڪڙي طبقي کي استعمال ڪندي ھڪڙي وڻ جي جوڙجڪ ۾ گھڻن شين کي گروپ ڪريو. توهان کي هڪ اعتراض ذريعي ڪيترن ئي طبقن سان ڪم ڪرڻ جي اجازت ڏئي ٿي.

عمل درآمد:

import java.util.ArrayList;
import java.util.List;
interface Car {
    void draw(String color);
}
class SportCar implements Car {
    public void draw(String color) {
        System.out.println("SportCar color: " + color);
    }
}
class UnknownCar implements Car {
    public void draw(String color) {
        System.out.println("UnknownCar color: " + color);
    }
}
class Drawing implements Car {
    private List<Car> cars = new ArrayList<Car>();
    public void draw(String color) {
        for(Car car : cars) {
            car.draw(color);
        }
    }
    public void add(Car s){
        this.cars.add(s);
    }
    public void clear(){
		System.out.println();
        this.cars.clear();
    }
}

public class CompositeTest {//тест
    public static void main(String[] args) {
        Car sportCar = new SportCar();
        Car unknownCar = new UnknownCar();
        Drawing drawing = new Drawing();
        drawing.add(sportCar);
        drawing.add(unknownCar);
        drawing.draw("green");
        drawing.clear();
        drawing.add(sportCar);
        drawing.add(unknownCar);
        drawing.draw("white");
    }
}

پراڪسي

وضاحت :

شين جي نمائندگي ڪري ٿو جيڪي ٻين شين کي ڪنٽرول ڪري سگھن ٿيون انهن جي ڪالن کي مداخلت ڪندي. اهو ممڪن آهي ته ڪال کي اصل اعتراض ڏانهن روڪيو وڃي.

عمل درآمد:

interface Image {
    void display();
}
class RealImage implements Image {
    private String file;
    public RealImage(String file){
        this.file = file;
        load(file);
    }
    private void load(String file){
        System.out.println("Загрузка " + file);
    }
    public void display() {
        System.out.println("Просмотр " + file);
    }
}
class ProxyImage implements Image {
    private String file;
    private RealImage image;
    public ProxyImage(String file){
        this.file = file;
    }
    public void display() {
        if(image == null){
            image = new RealImage(file);
        }
        image.display();
    }
}

public class ProxyTest {//тест
    public static void main(String[] args) {
        Image image = new ProxyImage("test.jpg");
        image.display();
        image.display();
    }
}

فلائي ويٽ

وضاحت :

هڪجهڙا شيون ٺاهڻ جي بدران، شيون ٻيهر استعمال ڪيون وينديون آهن. ياداشت بچائيندو آهي.

عمل درآمد:

class Flyweight {
    private int row;
    public Flyweight(int row) {
        this.row = row;
        System.out.println("ctor: " + this.row);
    }
    void report(int col) {
        System.out.print(" " + row + col);
    }
}

class Factory {
    private Flyweight[] pool;
    public Factory(int maxRows) {
        pool = new Flyweight[maxRows];
    }
    public Flyweight getFlyweight(int row) {
        if (pool[row] == null) {
            pool[row] = new Flyweight(row);
        }
        return pool[row];
    }
}

public class FlyweightTest {//тест
    public static void main(String[] args) {
        int rows = 5;
        Factory theFactory = new Factory(rows);
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < rows; j++) {
                theFactory.getFlyweight(i).report(j);
            }
            System.out.println();
        }
    }
}

منهن

وضاحت :

ھڪڙي ھڪڙي اعتراض تي سڀني ڪالن کي ڪاسٽ ڪندي ھڪڙي پيچيده طبقاتي نظام کي لڪايو. ھڪڙي ھڪڙي اعتراض ۾ گھڻن پيچيده شين کي ڪال ڪري ٿو.

عمل درآمد:

interface Car {
    void start();
    void stop();
}
class Key implements Car {
    public void start() {
        System.out.println("Вставить ключи");
    }
    public void stop() {
        System.out.println("Вытянуть ключи");
    }
}
class Engine implements Car {
    public void start() {
        System.out.println("Запустить двигатель");
    }
    public void stop() {
        System.out.println("Остановить двигатель");
    }
}
class Facade {
    private Key key;
    private Engine engine;
    public Facade() {
        key = new Key();
        engine = new Engine();
    }
    public void startCar() {
        key.start();
        engine.start();
    }
    public void stoptCar() {
        key.stop();
        engine.stop();
    }
}

public class FacadeTest {//тест
    public static void main(String[] args) {
        Facade facade = new Facade();
        facade.startCar();
        System.out.println();
        facade.stoptCar();
    }
}

پل

وضاحت :

الڳ الڳ عملدرآمد ۽ تجزيه، اهو ممڪن بڻائي ٿو ته انهن کي هڪ ٻئي کان آزاديء سان تبديل ڪرڻ. ڪنڪريٽ طبقن کي انٽرفيس لاڳو ڪرڻ واري طبقن کان آزاد بڻائي ٿو.

عمل درآمد:

interface Engine {
    void setEngine();
}
abstract class Car {
    protected Engine engine;
    public Car(Engine engine){
        this.engine = engine;
    }
    abstract public void setEngine();
}
class SportCar extends Car {
    public SportCar(Engine engine) {
        super(engine);
    }
    public void setEngine() {
        System.out.print("SportCar engine: ");
        engine.setEngine();
    }
}
class UnknownCar extends Car {
    public UnknownCar(Engine engine) {
        super(engine);
    }
    public void setEngine() {
        System.out.print("UnknownCar engine: ");
        engine.setEngine();
    }
}
class SportEngine implements Engine {
    public void setEngine(){
        System.out.println("sport");
    }
}
class UnknownEngine implements Engine {
    public void setEngine(){
        System.out.println("unknown");
    }
}
public class BridgeTest {//тест
    public static void main(String[] args) {
        Car sportCar = new SportCar(new SportEngine());
        sportCar.setEngine();
        System.out.println();
        Car unknownCar = new UnknownCar(new UnknownEngine());
        unknownCar.setEngine();
    }
}

سينگار ڪندڙ

وضاحت :

موجوده شئي ۾ نئين ڪارڪردگي شامل ڪري ٿو بغير ان جي جوڙجڪ کي پابند ڪرڻ.

عمل درآمد:

interface Car {
    void draw();
}
class SportCar implements Car {
    public void draw() {
        System.out.println("SportCar");
    }
}
class UnknownCar implements Car {
    public void draw() {
        System.out.println("UnknownCar");
    }
}
abstract class CarDecorator implements Car {
    protected Car decorated;
    public CarDecorator(Car decorated){
        this.decorated = decorated;
    }
    public void draw(){
        decorated.draw();
    }
}
class BlueCarDecorator extends CarDecorator {
    public BlueCarDecorator(Car decorated) {
        super(decorated);
    }
    public void draw() {
        decorated.draw();
        setColor();
    }
    private void setColor(){
        System.out.println("Color: red");
    }
}

public class DecoratorTest {//тест
    public static void main(String[] args) {
        Car sportCar = new SportCar();
        Car blueUnknownCar = new BlueCarDecorator(new UnknownCar());
        sportCar.draw();
        System.out.println();
        blueUnknownCar.draw();
    }
}

رويي وارو

ٽيمپليٽ جو طريقو

وضاحت :

توهان کي اجازت ڏئي ٿو ته هڪ الگورٿم جو بنياد بيان ڪري ۽ ذيلي ڪلاسز کي اجازت ڏئي ٿو ته ان جي مجموعي جوڙجڪ کي تبديل ڪرڻ کان سواءِ الگورٿم جي ڪجهه مرحلن کي اوور رائيڊ ڪري.

عمل درآمد:

abstract class Car {
    abstract void startEngine();
    abstract void stopEngine();

    public final void start(){
        startEngine();
        stopEngine();
    }
}
class OneCar extends Car {
    public void startEngine() {
        System.out.println("Start engine.");
    }
    public void stopEngine() {
        System.out.println("Stop engine.");
    }
}
class TwoCar extends Car {
    public void startEngine() {
        System.out.println("Start engine.");
    }
    public void stopEngine() {
        System.out.println("Stop engine.");
    }
}

public class TemplateTest {//тест
    public static void main(String[] args) {
        Car car1 = new OneCar();
        car1.start();
        System.out.println();
        Car car2 = new TwoCar();
        car2.start();
    }
}

ثالث

وضاحت :

ثالث طبقو مهيا ڪري ٿو جيڪو مختلف طبقن جي وچ ۾ سڀني رابطن کي سنڀاليندو آهي.

عمل درآمد:

class Mediator {
    public static void sendMessage(User user, String msg){
        System.out.println(user.getName() + ": " + msg);
    }
}
class User {
    private String name;
    public User(String name){
        this.name  = name;
    }
    public String getName() {
        return name;
    }
    public void sendMessage(String msg){
        Mediator.sendMessage(this, msg);
    }
}

public class MediatorTest {//тест
    public static void main(String[] args) {
        User user1 = new User("user1");
        User user2 = new User("user2");
        user1.sendMessage("message1");
        user2.sendMessage("message2");
    }
}

ذميواري جو سلسلو

وضاحت :

توهان کي اجازت ڏئي ٿو ته درخواست موڪليندڙ جي سخت انحصار کان بچڻ جي ان جي وصول ڪندڙ تي، جڏهن ته درخواست تي عمل ڪري سگهجي ٿو ڪيترن ئي شين طرفان.

عمل درآمد:

interface Payment {
    void setNext(Payment payment);
    void pay();
}
class VisaPayment implements Payment {
    private Payment payment;
    public void setNext(Payment payment) {
        this.payment = payment;
    }
    public void pay() {
        System.out.println("Visa Payment");
    }
}
class PayPalPayment implements Payment {
    private Payment payment;
    public void setNext(Payment payment) {
        this.payment = payment;
    }
    public void pay() {
        System.out.println("PayPal Payment");
    }
}

public class ChainofResponsibilityTest {//тест
    public static void main(String[] args) {
        Payment visaPayment = new VisaPayment();
        Payment payPalPayment = new PayPalPayment();
        visaPayment.setNext(payPalPayment);
        visaPayment.pay();
    }
}

مبصر

وضاحت :

ھڪڙي شئي کي اجازت ڏئي ٿي انھن ڪمن جو مشاهدو ڪري جيڪي ٻين شين ۾ ٿين ٿيون.

عمل درآمد:

import java.util.ArrayList;
import java.util.List;
interface Observer {
    void event(List<String> strings);
}
class University {
    private List<Observer> observers = new ArrayList<Observer>();
    private List<String> students = new ArrayList<String>();
    public void addStudent(String name) {
        students.add(name);
        notifyObservers();
    }
    public void removeStudent(String name) {
        students.remove(name);
        notifyObservers();
    }
    public void addObserver(Observer observer){
        observers.add(observer);
    }
    public void removeObserver(Observer observer) {
        observers.remove(observer);
    }
    public void notifyObservers(){
        for (Observer observer : observers) {
            observer.event(students);
        }
    }
}
class Director implements Observer {
    public void event(List<String> strings) {
        System.out.println("The list of students has changed: " + strings);
    }
}

public class ObserverTest {//тест
    public static void main(String[] args) {
        University university = new University();
        Director director = new Director();
        university.addStudent("Vaska");
        university.addObserver(director);
        university.addStudent("Anna");
        university.removeStudent("Vaska");
    }
}

حڪمت عملي

وضاحت :

انهن جي وچ ۾ رابطي جي اجازت ڏيڻ لاء ڪيترن ئي الگورتھم کي بيان ڪري ٿو. حڪمت عملي الگورتھم پروگرام جي عمل دوران تبديل ٿي سگھي ٿو.

عمل درآمد:

interface Strategy {
    void download(String file);
}
class DownloadWindownsStrategy implements Strategy {
    public void download(String file) {
        System.out.println("windows download: " + file);
    }
}
class DownloadLinuxStrategy implements Strategy {
    public void download(String file) {
        System.out.println("linux download: " + file);
    }
}
class Context {
    private Strategy strategy;
    public Context(Strategy strategy){
        this.strategy = strategy;
    }
    public void download(String file){
        strategy.download(file);
    }
}

public class StrategyTest {//тест
    public static void main(String[] args) {
        Context context = new Context(new DownloadWindownsStrategy());
        context.download("file.txt");
        context = new Context(new DownloadLinuxStrategy());
        context.download("file.txt");
    }
}

حڪم

وضاحت :

توهان کي اجازت ڏئي ٿي ته مختلف عملن کي الڳ الڳ شين ۾ شامل ڪريو.

عمل درآمد:

interface Command {
    void execute();
}
class Car {
    public void startEngine() {
        System.out.println("запустить двигатель");
    }
    public void stopEngine() {
        System.out.println("остановить двигатель");
    }
}
class StartCar implements Command {
    Car car;
    public StartCar(Car car) {
        this.car = car;
    }
    public void execute() {
        car.startEngine();
    }
}
class StopCar implements Command {
    Car car;
    public StopCar(Car car) {
        this.car = car;
    }
    public void execute() {
        car.stopEngine();
    }
}
class CarInvoker {
    public Command command;
    public CarInvoker(Command command){
        this.command = command;
    }
    public void execute(){
        this.command.execute();
    }
}

public class CommandTest {//тест
    public static void main(String[] args) {
        Car car = new Car();
        StartCar startCar = new StartCar(car);
        StopCar stopCar = new StopCar(car);
        CarInvoker carInvoker = new CarInvoker(startCar);
        carInvoker.execute();
    }
}

رياست

وضاحت :

ڪنهن شئي کي اجازت ڏئي ٿو ته ان جي حالت تي منحصر ڪري ان جي رويي کي تبديل ڪري.

عمل درآمد:

interface State {
    void doAction();
}
class StartPlay implements State {
    public void doAction() {
        System.out.println("start play");
    }
}
class StopPlay implements State {
    public void doAction() {
        System.out.println("stop play");
    }
}
class PlayContext implements State {
    private State state;
    public void setState(State state){
        this.state = state;
    }
    public void doAction() {
        this.state.doAction();
    }
}

public class StateTest {//тест
    public static void main(String[] args) {
        PlayContext playContext = new PlayContext();
        State startPlay = new StartPlay();
        State stopPlay = new StopPlay();
        playContext.setState(startPlay);
        playContext.doAction();
        playContext.setState(stopPlay);
        playContext.doAction();
    }
}

گهمڻ وارو

وضاحت :

لاڳاپيل شين جي گروپن تي عمل کي آسان ڪرڻ لاء استعمال ڪيو ويو.

عمل درآمد:

interface Visitor {
    void visit(SportCar sportCar);
    void visit(Engine engine);
    void visit(Whell whell);
}
interface Car {
    void accept(Visitor visitor);
}
class Engine implements Car {
    public void accept(Visitor visitor) {
        visitor.visit(this);
    }
}
class Whell implements Car {
    public void accept(Visitor visitor) {
        visitor.visit(this);
    }
}
class SportCar implements Car {
    Car[] cars;
    public SportCar(){
        cars = new Car[]{new Engine(), new Whell()};
    }
    public void accept(Visitor visitor) {
        for (int i = 0; i < cars.length; i++) {
            cars[i].accept(visitor);
        }
        visitor.visit(this);
    }
}
class CarVisitor implements Visitor {
    public void visit(SportCar computer) {
        print("car");
    }
    public void visit(Engine engine) {
        print("engine");
    }
    public void visit(Whell whell) {
        print("whell");
    }
    private void print(String string) {
        System.out.println(string);
    }
}

public class VisitorTest {//тест
    public static void main(String[] args) {
        Car computer = new SportCar();
        computer.accept(new CarVisitor());
    }
}

مترجم

وضاحت :

توھان کي اجازت ڏئي ٿو ھڪڙي سادي ٻوليءَ جي گرامر کي ھڪڙي مسئلي جي ڊومين لاءِ.

عمل درآمد:

interface Expression {
    String interpret(Context context);
}
class Context {
    public String getLowerCase(String s){
        return s.toLowerCase();
    }
    public String getUpperCase(String s){
        return s.toUpperCase();
    }
}
class LowerExpression implements Expression {
    private String s;
    public LoverExpression(String s) {
        this.s = s;
    }
    public String interpret(Context context) {
        return context.getLoverCase(s);
    }
}
class UpperExpression implements Expression {
    private String s;
    public UpperExpression(String s) {
        this.s = s;
    }
    public String interpret(Context context) {
        return context.getUpperCase(s);
    }
}

public class InterpreterTest {//тест
    public static void main(String[] args) {
        String str = "TesT";
        Context context = new Context();
        Expression loverExpression = new LoverExpression(str);
        str = loverExpression.interpret(context);
        System.out.println(str);
        Expression upperExpression = new UpperExpression(str);
        str = upperExpression.interpret(context);
        System.out.println(str);
    }
}

ورجائيندڙ

وضاحت :

ترتيب سان ان جي بنيادي نمائندگي کي ڄاڻڻ کان سواء گڏ ڪيل اعتراض جي عناصر تائين رسائي حاصل ڪري ٿي.

عمل درآمد:

interface Iterator {
    boolean hasNext();
    Object next();
}
class Numbers {
    public int num[] = {1 , 2, 3};
    public Iterator getIterator() {
        return new NumbersIterator();
    }
    private class NumbersIterator implements Iterator {
        int ind;
        public boolean hasNext() {
            if(ind < num.length) return true;
            return false;
        }
        public Object next() {
            if(this.hasNext()) return num[ind++];
            return null;
        }
    }
}

public class IteratorTest {//тест
    public static void main(String[] args) {
        Numbers numbers = new Numbers();
        Iterator iterator = numbers.getIterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }
    }
}

يادگار (گارڊين)

وضاحت :

توهان کي اعتراض جي موجوده حالت کي بچائڻ جي اجازت ڏئي ٿي؛ هن رياست کي بعد ۾ بحال ڪري سگهجي ٿو. encapsulation کي ٽوڙي نه ٿو.

عمل درآمد:

import java.util.ArrayList;
import java.util.List;
class Memento {
    private String name;
    private int age;
    public Memento(String name, int age){
        this.name = name;
        this.age = age;
    }
    public String getName() {
        return name;
    }
    public int getAge() {
        return age;
    }
}
class User {
    private String name;
    private int age;
    public User(String name, int age) {
        this.name = name;
        this.age = age;
        System.out.println(String.format("create: name = %s, age = %s", name, age));
    }
    public Memento save(){
        System.out.println(String.format("save: name = %s, age = %s", name, age));
        return new Memento(name, age);
    }
    public void restore(Memento memento){
        name = memento.getName();
        age = memento.getAge();
        System.out.println(String.format("restore: name = %s, age = %s", name, age));
    }
}
class SaveUser {
    private List<Memento> list = new ArrayList<Memento>();
    public void add(Memento memento){
        list.

تبصرا

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