请根据观察者模式，用Java语言设计并实现气象站程序。

package cn.edu.qust.dp.object; import java.util.ArrayList; import java.util.List; import cn.edu.qust.dp.Interface.DisplayElement; import cn.edu.qust.dp.Interface.Observer; import cn.edu.qust.dp.Interface.Subject; public class StatisticsDisplay implements Observer, DisplayElement { //具体的观察者 private List<Float> statistics; private float Avg; private float Max; private float Min; private Subject weatherData; public StatisticsDisplay(Subject weatherData){ //指定气象站并注册 this.weatherData = weatherData; weatherData.registerObserver(this); statistics = new ArrayList<>(); } @Override public void display() { //找出最值 Max = Min = statistics.get(0); for(int i = 0;i < statistics.size();i++){ if (statistics.get(i) > Max){ Max = statistics.get(i); } if (statistics.get(i) < Min){ Min = statistics.get(i); } } Avg = 0; for(int i = statistics.size()-1; i >= 0; i--){ Avg += statistics.get(i); } Avg = Avg/statistics.size(); System.out.println("Avg/Max/Min:" + "temperature = " + Avg + "/" + Max + "/" + Min + "/" + " (by 1508060330)"); } @Override public void update(float temp, float humidity, float pressure) { //控制缓存三天天气 if(statistics.size() > 3){ //删除旧元素 statistics.remove(0); } //添加新元素 statistics.add(temp); //更新后显示 display(); } }