Observer pattern [2]

Aug 24 posted in Java (RSS), comments.

Advertisements

package observerDM;

import java.util.Observable;

public class ConcreteSubject extends Observable {

        public ConcreteSubject(String _name , float _price) {
                this.name = _name;
                this.price = _price;
                System.out.println("ConcreteSubject created:" + _name + "at" + _price);
        }
        
        public String getName() {
                return name;
        }
        public void setName(String name) {
                this.name = name;
                setChanged();
                notifyObservers(name);
        }
        public float getPrice() {
                return price;
        }
        public void setPrice(float price) {
                this.price = price;
                setChanged();
                notifyObservers(price);
        }

        private String name ;
        private float price ;
}

package observerDM;

import java.util.Observable;
import java.util.Observer;

public class NameObserver implements Observer {

        public NameObserver() {
                this.name = null ;
                System.out.println("NameObserver has created:Name is :" + this.name);
        }
        
        public void update(Observable o, Object arg) {
                
                if(arg instanceof String) {
                        name = (String)arg;
                        System.out.println("NameObserver has changed:Name is :" + name);
                }else {
                        System.out.println("NameObserver :some other change to subject");
                }
        }
        
        private String name ;
}

package observerDM;

import java.util.Observable;
import java.util.Observer;

public class PriceObserver implements Observer {

        public PriceObserver() {
                this.price = 0 ;
                System.out.println("PriceObserver has created : Price is :" + price);
        }
        
        public void update(Observable o, Object arg) {
                if(arg instanceof Float) {
                        price = ((Float)arg).floatValue();
                        System.out.println("PriceObserver has changed:Price is :" + price);
                }else {
                        System.out.println("PriceObserver :some other change to subject");
                }
        }
        
        private float price ;
}

package observerDM;

public class TestObservers {
        
        public static void main(String[] args){
                
                ConcreteSubject sub = new ConcreteSubject("Com pops",(float)1.30);
                
                NameObserver name = new NameObserver();
                PriceObserver price = new PriceObserver();
                
                sub.addObserver(name);
                sub.addObserver(price);
                
                sub.setName("Frosted Flakes");
                sub.setPrice((float)1.40);
                
                sub.setPrice((float)2.03);
                sub.setName("helloWorld");
        }
}