Примеры шаблонов проектирования

Приведите примеры основных шаблонов проектирования

Примеры основных шаблонов проектирования на Java:

Singleton:

public class Singleton {
    private static Singleton instance;

    private Singleton() {}

    public static synchronized Singleton getInstance() {
        if (instance == null) {
            instance = new Singleton();
        }
        return instance;
    }
}

Factory Method:

public interface Product {
    void use();
}

public class ConcreteProduct implements Product {
    public void use() {
        System.out.println("Using ConcreteProduct");
    }
}

public abstract class Creator {
    public abstract Product factoryMethod();

    public void someOperation() {
        Product product = factoryMethod();
        product.use();
    }
}

public class ConcreteCreator extends Creator {
    public Product factoryMethod() {
        return new ConcreteProduct();
    }
}

Abstract Factory:

public interface GUIFactory {
    Button createButton();
    Checkbox createCheckbox();
}

public class WinFactory implements GUIFactory {
    public Button createButton() {
        return new WinButton();
    }
    public Checkbox createCheckbox() {
        return new WinCheckbox();
    }
}

public class MacFactory implements GUIFactory {
    public Button createButton() {
        return new MacButton();
    }
    public Checkbox createCheckbox() {
        return new MacCheckbox();
    }
}

Приведите примеры порождающих шаблонов проектирования

Примеры порождающих шаблонов проектирования на Java:

Singleton:

public class Singleton {
    private static Singleton instance;

    private Singleton() {}

    public static synchronized Singleton getInstance() {
        if (instance == null) {
            instance = new Singleton();
        }
        return instance;
    }
}

Factory Method:

public interface Product {
    void use();
}

public class ConcreteProduct implements Product {
    public void use() {
        System.out.println("Using ConcreteProduct");
    }
}

public abstract class Creator {
    public abstract Product factoryMethod();

    public void someOperation() {
        Product product = factoryMethod();
        product.use();
    }
}

public class ConcreteCreator extends Creator {
    public Product factoryMethod() {
        return new ConcreteProduct();
    }
}

Abstract Factory:

public interface GUIFactory {
    Button createButton();
    Checkbox createCheckbox();
}

public class WinFactory implements GUIFactory {
    public Button createButton() {
        return new WinButton();
    }
    public Checkbox createCheckbox() {
        return new WinCheckbox();
    }
}

public class MacFactory implements GUIFactory {
    public Button createButton() {
        return new MacButton();
    }
    public Checkbox createCheckbox() {
        return new MacCheckbox();
    }
}

Builder:

public class Product {
    private String part1;
    private String part2;

    public void setPart1(String part1) {
        this.part1 = part1;
    }

    public void setPart2(String part2) {
        this.part2 = part2;
    }
}

public abstract class Builder {
    protected Product product = new Product();

    public abstract void buildPart1();
    public abstract void buildPart2();

    public Product getResult() {
        return product;
    }
}

public class ConcreteBuilder extends Builder {
    public void buildPart1() {
        product.setPart1("Part 1");
    }

    public void buildPart2() {
        product.setPart2("Part 2");
    }
}

public class Director {
    public void construct(Builder builder) {
        builder.buildPart1();
        builder.buildPart2();
    }
}

Prototype:

public abstract class Prototype implements Cloneable {
    public Prototype clone() throws CloneNotSupportedException {
        return (Prototype) super.clone();
    }
}

public class ConcretePrototype extends Prototype {
    private String field;

    public void setField(String field) {
        this.field = field;
    }

    public String getField() {
        return field;
    }
}

Приведите примеры структурных шаблонов проектирования

Примеры структурных шаблонов проектирования на Java:

Adapter:

public interface Target {
    void request();
}

public class Adaptee {
    public void specificRequest() {
        System.out.println("Specific request");
    }
}

public class Adapter implements Target {
    private Adaptee adaptee;

    public Adapter(Adaptee adaptee) {
        this.adaptee = adaptee;
    }

    public void request() {
        adaptee.specificRequest();
    }
}

Composite:

public interface Component {
    void operation();
}

public class Leaf implements Component {
    public void operation() {
        System.out.println("Leaf operation");
    }
}

public class Composite implements Component {
    private List<Component> children = new ArrayList<>();

    public void add(Component component) {
        children.add(component);
    }

    public void remove(Component component) {
        children.remove(component);
    }

    public void operation() {
        for (Component child : children) {
            child.operation();
        }
    }
}

Decorator:

public interface Component {
    void operation();
}

public class ConcreteComponent implements Component {
    public void operation() {
        System.out.println("ConcreteComponent operation");
    }
}

public class Decorator implements Component {
    protected Component component;

    public Decorator(Component component) {
        this.component = component;
    }

    public void operation() {
        component.operation();
    }
}

public class ConcreteDecorator extends Decorator {
    public ConcreteDecorator(Component component) {
        super(component);
    }

    public void operation() {
        super.operation();
        additionalOperation();
    }

    private void additionalOperation() {
        System.out.println("ConcreteDecorator additional operation");
    }
}

Facade:

public class Subsystem1 {
    public void operation1() {
        System.out.println("Subsystem1 operation1");
    }
}

public class Subsystem2 {
    public void operation2() {
        System.out.println("Subsystem2 operation2");
    }
}

public class Facade {
    private Subsystem1 subsystem1 = new Subsystem1();
    private Subsystem2 subsystem2 = new Subsystem2();

    public void operation() {
        subsystem1.operation1();
        subsystem2.operation2();
    }
}

Proxy:

public interface Subject {
    void request();
}

public class RealSubject implements Subject {
    public void request() {
        System.out.println("RealSubject request");
    }
}

public class Proxy implements Subject {
    private RealSubject realSubject;

    public void request() {
        if (realSubject == null) {
            realSubject = new RealSubject();
        }
        realSubject.request();
    }
}

Приведите примеры поведенческих шаблонов проектирования

Примеры поведенческих шаблонов проектирования на Java:

Observer:

public interface Observer {
    void update(String state);
}

public class ConcreteObserver implements Observer {
    private String state;

    public void update(String state) {
        this.state = state;
        System.out.println("State updated to: " + state);
    }
}

public class Subject {
    private List<Observer> observers = new ArrayList<>();
    private String state;

    public void attach(Observer observer) {
        observers.add(observer);
    }

    public void detach(Observer observer) {
        observers.remove(observer);
    }

    public void notifyObservers() {
        for (Observer observer : observers) {
            observer.update(state);
        }
    }

    public void setState(String state) {
        this.state = state;
        notifyObservers();
    }
}

Strategy:

public interface Strategy {
    void execute();
}

public class ConcreteStrategyA implements Strategy {
    public void execute() {
        System.out.println("Executing strategy A");
    }
}

public class ConcreteStrategyB implements Strategy {
    public void execute() {
        System.out.println("Executing strategy B");
    }
}

public class Context {
    private Strategy strategy;

    public void setStrategy(Strategy strategy) {
        this.strategy = strategy;
    }

    public void executeStrategy() {
        strategy.execute();
    }
}

Command:

public interface Command {
    void execute();
}

public class ConcreteCommand implements Command {
    private Receiver receiver;

    public ConcreteCommand(Receiver receiver) {
        this.receiver = receiver;
    }

    public void execute() {
        receiver.action();
    }
}

public class Receiver {
    public void action() {
        System.out.println("Receiver action");
    }
}

public class Invoker {
    private Command command;

    public void setCommand(Command command) {
        this.command = command;
    }

    public void executeCommand() {
        command.execute();
    }
}

Iterator:

public interface Iterator {
    boolean hasNext();
    Object next();
}

public class ConcreteIterator implements Iterator {
    private List<Object> items;
    private int position = 0;

    public ConcreteIterator(List<Object> items) {
        this.items = items;
    }

    public boolean hasNext() {
        return position < items.size();
    }

    public Object next() {
        return items.get(position++);
    }
}

public interface Aggregate {
    Iterator createIterator();
}

public class ConcreteAggregate implements Aggregate {
    private List<Object> items = new ArrayList<>();

    public void addItem(Object item) {
        items.add(item);
    }

    public Iterator createIterator() {
        return new ConcreteIterator(items);
    }
}

State:

public interface State {
    void handle();
}

public class ConcreteStateA implements State {
    public void handle() {
        System.out.println("Handling state A");
    }
}

public class ConcreteStateB implements State {
    public void handle() {
        System.out.println("Handling state B");
    }
}

public class Context {
    private State state;

    public void setState(State state) {
        this.state = state;
    }

    public void request() {
        state.handle();
    }
}