设计模式之观察者模式(java内置)

DisplayElement.java,WeatherStation.java同上

WeatherData.java

import java.util.Observable;

public class WeatherData extends Observable {

    private float temperature;
    private float humidity;
    private float pressure;

    public float getTemperature() {
        return temperature;
    }

    public float getHumidity() {
        return humidity;
    }

    public float getPressure() {
        return pressure;
    }

    public WeatherData() {
    }

    public void measurementsChanged(){
        setChanged();
        notifyObservers();
    }

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

CurrentConditionDisplay.java

import java.util.Observable;
import java.util.Observer;

public class CurrentConditionDisplay implements Observer, DisplayElement {
-
    private float temperature;
    private float humidity;
    Observable observable;

    public CurrentConditionDisplay(Observable observable) {
            this.observable = observable;
            observable.addObserver(this);
    }

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

    @Override
    public void update(Observable obs, Object arg) {
        if (obs instanceof WeatherData) {
            WeatherData weatherData = (WeatherData) obs;
            this.temperature = weatherData.getTemperature();
            this.humidity = weatherData.getHumidity();
            display();
        }
    }
}

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