heatindexdisplay.java

深入浅出设计模式

package headfirst.observer.weatherobservable;

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

public class HeatIndexDisplay implements Observer, DisplayElement {
	float heatIndex = 0.0f;

	public HeatIndexDisplay(Observable observable) {
		observable.addObserver(this);
	}

	public void update(Observable observable, Object arg) {
		if (observable instanceof WeatherData) {
			WeatherData weatherData = (WeatherData)observable;
			float t = weatherData.getTemperature();
			float rh = weatherData.getHumidity();
			heatIndex = (float)
				(
				(16.923 + (0.185212 * t)) + 
				(5.37941 * rh) - 
				(0.100254 * t * rh) + 
				(0.00941695 * (t * t)) + 
				(0.00728898 * (rh * rh)) + 
				(0.000345372 * (t * t * rh)) - 
				(0.000814971 * (t * rh * rh)) +
				(0.0000102102 * (t * t * rh * rh)) - 
				(0.000038646 * (t * t * t)) + 
				(0.0000291583 * (rh * rh * rh)) +
				(0.00000142721 * (t * t * t * rh)) + 
				(0.000000197483 * (t * rh * rh * rh)) - 
				(0.0000000218429 * (t * t * t * rh * rh)) +
				(0.000000000843296 * (t * t * rh * rh * rh)) -
				(0.0000000000481975 * (t * t * t * rh * rh * rh)));
			display();
		}
	}

	public void display() {
		System.out.println("Heat index is " + heatIndex);
	}
}