package com.observer.theory;public class Test{    public static void main(String[] args)    {        StockData data=new StockData(16.1f,15.0f,17.2f,16.9f);                Buyer buyer=new Buyer(data);        Trading trading=new Trading(data);                data.setStockData(16.1f,15.0f,17.4f,16.9f);        data.setStockData(16.1f,14.5f,17.4f,16.9f);            }}package com.observer.theory;import java.util.Observable;import java.util.Observer;public class Trading implements Observer{    public Trading(Observable o)    {        o.addObserver(this);    }    @Override    public void update(Observable o, Object arg)    {        if(o instanceof StockData)        {            StockData data=(StockData)o;            System.out.println("交易报告:");            System.out.print("开盘价:"+data.getOpen());            System.out.print("收盘价:"+data.getClose());            System.out.print("最低价:"+data.getLow());            System.out.print("最高价:"+data.getHigh());            System.out.println("");        }    }        }package com.observer.theory;import java.util.Observable;import java.util.Observer;public class Buyer implements Observer{        public Buyer(Observable o)    {        o.addObserver(this);    }    @Override    public void update(Observable o, Object arg)    {        if(o instanceof StockData)        {            StockData data=(StockData)o;            System.out.println("买家报告:");            System.out.print("开盘价:"+data.getOpen());            System.out.print("收盘价:"+data.getClose());            System.out.print("最低价:"+data.getLow());            System.out.print("最高价:"+data.getHigh());            System.out.println("");        }    }        }package com.observer.theory;import java.util.Observable;import java.util.Observer;public class StockData extends Observable{    private float open;    private float low;    private float high;    private float close;    public StockData(float open, float low, float high, float close)    {        super();        this.open = open;        this.low = low;        this.high = high;        this.close = close;    }    public float getOpen()    {        return open;    }    public void setOpen(float open)    {        this.open = open;    }    public float getLow()    {        return low;    }    public void setLow(float low)    {        this.low = low;    }    public float getHigh()    {        return high;    }    public void setHigh(float high)    {        this.high = high;    }    public float getClose()    {        return close;    }    public void setClose(float close)    {        this.close = close;    }        public void setStockData(float open, float low, float high, float close)    {        this.open = open;        this.low = low;        this.high = high;        this.close = close;            setChanged();        notifyObservers();    }    }