multiple inherited (implements) with generics classes

multiple inherited with generics classes
May 1, 2007 11:04 AM

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Hello all, here is my generic observer/ subject code.

package jstock;

/**
 *
 * @author yccheok
 */
public interface Observer<S, A> {
    public void update(S subject, A arg);

}

public class Subject<S, A> {

    public void attach(Observer<S, A> observer) {
        observers.add(observer);
    }

    void notify(S subject, A arg) {
        for (Observer<S, A> obs : observers) {
            obs.update(subject, arg);
        }
    }

    private List<Observer<S, A>> observers = new
CopyOnWriteArrayList<Observer<S, A>>();

}

However, when I try to implements more than one class (single class
only is ok), I get the following error :

/home/yccheok/Projects/jstock/src/org/yccheok/jstock/gui/
MainFrame.java:40: org.yccheok.jstock.engine.Observer cannot be
inherited with different arguments:
<org.yccheok.jstock.engine.RealTimeStockMonitor,java.util.List<org.yccheok.jstock.engine.Stock>>
and
<org.yccheok.jstock.engine.StockHistoryMonitor,org.yccheok.jstock.engine.StockHistoryServer>
public class MainFrame extends javax.swing.JFrame implements

Here is the code which I am implementing the generic classes.

public class MainFrame extends javax.swing.JFrame implements
org.yccheok.jstock.engine.Observer<RealTimeStockMonitor,
java.util.List<org.yccheok.jstock.engine.Stock>>,
org.yccheok.jstock.engine.Observer<StockHistoryMonitor,
StockHistoryServer>

May I know how I can avoid the error message?

Thank you.

cheok