package magicbeans;

import java.beans.*;

public class Multiplier implements java.io.Serializable {
	private double a, b, c;
	
	synchronized public void setA( double val ) { 
		a = val; 
		multiply();
	}

	synchronized public double getA() { 
		return a; 
	}

	synchronized public void setB( double val ) { 
		b = val; 
		multiply();
	}

	synchronized public double getB() { 
		return b; 
	}

	synchronized public double getC() { 
		return c; 
	} 	

	synchronized public void setC( double val ) { 
		multiply();
	} 	

	private void multiply() {
		double oldC = c;
		c = a * b;
		propChanges.firePropertyChange( 
			"C", new Double(oldC) , new Double(c) );
	}

    private PropertyChangeSupport propChanges = new PropertyChangeSupport(this);

	public void addPropertyChangeListener(PropertyChangeListener listener) {
        propChanges.addPropertyChangeListener(listener);
    }
    public void removePropertyChangeListener(PropertyChangeListener listener) {
        propChanges.removePropertyChangeListener(listener);
	}
}