SE450: Observer: 7 [22/28] Previous pageContentsNext page

file:Main.java [source] [doc-public] [doc-private]
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package observer.seven;
import java.util.Observer;
import java.util.Observable;
public class Main {
  public static void main(String[] argv) {
    Int c = new Int();
    c.addObserver(new IntObserver());
    Runnable r1 = new M(c);
    Runnable r2 = new N(c);
    for (int i=0; i<10000; i++) {
      r1.run();
      r2.run();
    }
  }
}
class IntObserver implements Observer {
  private int numOps;
  public void update(Observable o, Object arg) {
    System.out.println (++numOps);
  }
}
class Int extends Observable {
  private int v;
  public int get() { return v; }
  public void inc() { v++; setChanged(); notifyObservers(); }
  public void dec() { v--; setChanged(); notifyObservers(); }
}
class M implements Runnable {
  private Int c;
  public M(Int c) { this.c = c; }
  public void run() {
    c.inc();
    c.inc();
    c.dec();
  }
}
class N implements Runnable {
  private Int c;
  public N(Int c) { this.c = c; }
  public void run() {
    for (int i=0; i<50; i++) {
      if (i%3==0) {
        c.dec();
      } else {
        c.inc();
      }
    }
  }
}

java.util.Observable
java.util.Observer

Is it worth giving IntObserver a name?

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