阅读下列说明和Java代码,将应填入 (n)处的字句卸载答题纸的对应栏内. 【说明】 某实验室欲建

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阅读下列说明和Java代码,将应填入 (n)处的字句卸载答题纸的对应栏内. 【说明】 某实验室欲建立一个实验室环境监测系统,能够显示实验室的温度、湿度以及洁净度等环境数据。当获取到最新的环境测量数据时,显示的环境数据能够更新。 现在采用观察者(Observer)模式来开发该系统。观察者模式的类图如图6-1所示。 【Java代码】 import java.util.*; interface Observer { public void update(float temp, float humidity, float cleanness); } interface Subject { public void registerObserver(Observer o); //注册对主题感兴趣的观察者 public void removeObserver(Observer o); //删除观察者 public void notifyObservers(); //当主题发生变化时通知观察者 } class EnvironmentData implements (1) { private ArrayList observers; private float temperature, humidity, cleanness; public EnvironmentData() { observers = new ArrayList(); } public void registerObserver(Observer o) { observers.add(o); } public void removeObserver(Observer o) { /* 代码省略 */ } public void notifyObservers() { for (int i = 0; i < observers.size(); i++) { Observer observer = (Observer)observers.get(i); (2) ; } } public void measurementsChanged() { (3) ; } public void setMeasurements(float temperature, float humidity, float cleanness) { this.temperature = temperature; this.humidity = humidity; this.cleanness = cleanness; (4) ; } } class CurrentConditionsDisplay implements (5) { private float temperature; private float humidity; private float cleanness; private Subject envData; public CurrentConditionsDisplay(Subject envData) { this.envData = envData; (6) ; } public void update(float temperature, float humidity, float cleanness) { this.temperature = temperature; this.humidity = humidity; this.cleanness = cleanness; display(); } public void display() {/* 代码省略 */ } } class EnvironmentMonitor{ public static void main(String[] args) { EnvironmentData envData = new EnvironmentData(); CurrentConditionsDisplay currentDisplay = new CnrrentConditionsDisplay(envData); envData.setMeasurements(80, 65, 30.4f); } } 请帮忙给出正确答案和分析,谢谢!
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