analysisdisplay.java

基于股票价格变化的观察者模式的java源代码。初学者可看

public class AnalysisDisplay implements Observer,
  DisplayElement{
	private float price;
	private float lowestPrice;
	private float averagePrice;
	private float highestPrice;
	private Stock stockData;	
	private int count = 0;    //价格变动次数
	public AnalysisDisplay(Stock stockData){
		this.stockData = stockData;
		stockData.registerObserver(this);
	}
	public void update(float price){
		count++;
		this.price = price;
		if(lowestPrice == 0 && averagePrice == 0 &&
				highestPrice == 0)
		{
			lowestPrice = this.price;
			averagePrice = this.price;
			highestPrice = this.price;
		}
		if(price < lowestPrice)
		{
			lowestPrice = price;
		}
		if(price > highestPrice)
		{
			highestPrice = price;
		}
		averagePrice = (averagePrice*(count-1) + price)
		                  /count;
		display();
	}
	public void display(){
		System.out.println("股票的最低价格为:"+lowestPrice);
		System.out.println("股票的最高价格为:"+highestPrice);
		System.out.println("股票的平均价格为:"+averagePrice);
	}
	
}