傍観者モード-(1)

傍観者モードとは?

こうぞう

例

package ObserverPattern.Interface;

public interface Observer {
    public void update(float temp, float humidity, float pressure);
}

package ObserverPattern.Interface;

public interface Subject {
    public void registerObserver(Observer o);
    public void removeObserver(Observer o);
    public void notifyObservers();
}

package ObserverPattern;

import ObserverPattern.Interface.Observer;
import ObserverPattern.Interface.Subject;

import java.util.ArrayList;

public class WeatherData implements Subject {
    private ArrayList observers;
    private float temperature;
    private float humidity;
    private float pressure;

    public WeatherData() {
        observers = new ArrayList();
    }
    @Override
    public void registerObserver(Observer o) {
        observers.add(o);
    }

    @Override
    public void removeObserver(Observer o) {
        int i = observers.indexOf(o);
        if (i >= 0) {
            observers.remove(i);
        }
    }

    @Override
    public void notifyObservers() {
        for (int i=0; i < observers.size(); i++) {
            Observer observer = (Observer) observers.get(i);
            observer.update(temperature,humidity,pressure);
        }
    }

    public void measurementsChanged() {
        notifyObservers();
    }

    public void setMeasurements(float temperature, float humidity, float pressure) {
        this.temperature = temperature;
        this.humidity = humidity;
        this.pressure = pressure;
        measurementsChanged();
    }
}

package ObserverPattern.Display;

import ObserverPattern.Interface.DisplayElement;
import ObserverPattern.Interface.Observer;
import ObserverPattern.Interface.Subject;

public class CurrentConditionsDisplay implements Observer, DisplayElement {
    private float temperature;
    private float humidity;
    private Subject weatherData;

    public CurrentConditionsDisplay(Subject weatherData) {
        this.weatherData = weatherData;
        weatherData.registerObserver(this);
    }

    @Override
    public void display() {
        System.out.println("Current conditions: " + temperature + "F Degrees and " + humidity + "% humidity");
    }

    @Override
    public void update(float temp, float humidity, float pressure) {
        this.temperature = temp;
        this.humidity = humidity;
        display();
    }
}

package ObserverPattern;

import ObserverPattern.Display.CurrentConditionsDisplay;

public class WeatherStation {
    public static void main(String[] args) {
        WeatherData weatherData = new WeatherData();

        CurrentConditionsDisplay currentConditionsDisplay = new CurrentConditionsDisplay(weatherData);

        weatherData.setMeasurements(80,65,30.4f);
        weatherData.setMeasurements(82,70,29.2f);
    }
}