设计模式学习--观察者模式(Observer Pattern) (八)

package weatherObservable;

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

/**
* 天气统计布告板
* @author wwj
*
*/
public class StatisticsDisplay implements Observer, DisplayElement {
private float maxTemp = 0.0f;; //最大温度
private float minTemp = 200; //最小温度
private float tempSum = 0.0f; //统计温度和
private int numReadings; //统计温度次数
private Observable observable;

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

@Override
public void display() {
System.out.println("Avg/Max/Min temperature = " + (tempSum / numReadings) + "/" + maxTemp + "/" + minTemp);
}

@Override
public void update(Observable obs, Object arg) {
if(obs instanceof WeatherData) {
WeatherData weatherData = (WeatherData)obs;
float temp = weatherData.getTemperature();
tempSum += temp;
numReadings++;

if (temp > maxTemp) {
maxTemp = temp;
}

if (temp < minTemp) {
minTemp = temp;
}

display();
}
}

}

[java]
package weatherObservable;

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

/**
* 酷热指数布告板
*
* @author wwj
* 注：那个计算酷热指数的公式不必深究
*/
public class HeatIndexDisplay implements Observer, DisplayElement {
float heatIndex = 0.0f;
private WeatherData weatherData;
private Observable observable;

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

private float computeHeatIndex(float t, float rh) {
float index = (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)));
return index;
}

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

@Override
public void update(Observable obs, Object arg) {
if(obs instanceof WeatherData) {
WeatherData weatherData = (WeatherData)observable;
float t = weatherData.getTemperature();