I have a Java class, named Main, which instances several classes with name Subscriber. Subscriber obtains data from the internet and when it obtains a new data it stores it in a variable. When a new data is saved I want it to notify Main, or that it detects it. How could I do it?
I have thought about using the Observer pattern but in my case I have an observer and many observed
Try this.
public class Stack1 {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
Producer p = new A();
for (int i = 0; i < 10; i++) {
Subscriber s = new B(p);
}
p.sendAll(new Data(1));
p.sendAll(new Data(2));
p.sendAll(new Data(3));
p.sendAll(new Data(4));
}
public static class Data implements Serializable {
private static final long serialVersionUID = 3897786191139169609L;
private Integer value;
public Data(Integer value) {
this.value = value;
}
@Override
public String toString() {
return "Data{" + "value=" + value + '}';
}
}
public interface Subscriber {
public void doSomething(Data data);
}
public interface Producer {
public void addSubscriber(Subscriber subscriber);
public void sendAll(Data data);
}
public static class A implements Producer {
private List<Subscriber> lst = new ArrayList<>();
@Override
public void addSubscriber(Subscriber subscriber) {
lst.add(subscriber);
}
@Override
public void sendAll(Data data) {
for (Subscriber subscriber : lst) {
subscriber.doSomething(data);
}
}
}
public static class B implements Subscriber {
private final String id;
public B(Producer producer) {
producer.addSubscriber(this);
id = UUID.randomUUID().toString();
}
@Override
public void doSomething(Data data) {
System.out.println(id.concat(" it.bookingexpert.test.Stack1.B.doSomething() ".concat(data.toString())));
}
}
}
