debug10_5.java

来自「程序练习中包括书中实例程序代码和练习中要用到的代码,是压缩文件」· Java 代码 · 共 39 行

package questions.c10;
import java.util.Observable;
import java.util.Observer;
public class Debug10_5 {
   public static void main( String[] args ) {
      FireStation fs = new FireStation();
      FireAlarm fa = new FireAlarm();
      fa.addObserver( fs );
      fa.soundAlarm();
      fa.clearAlarm();
   }
   static private class FireAlarm {
      private boolean alarmOn;
      public boolean isAlarmOn() {
         return alarmOn;
      }
      public void soundAlarm() {
         alarmOn = true;
         setChanged();
         notifyObservers();
      }
      public void clearAlarm() {
         alarmOn = false;
         setChanged();
         notifyObservers();
      }
   }
   static private class FireStation
                        implements Observer {
      public void update( FireAlarm fa, Object arg ) {
          if ( fa.isAlarmOn() ) {
             System.out.println( "Go to fire!" );
          } else {
             System.out.println( "Go back to"
                                 + "station." );
          }
      }
   }
}