Code example for Observable

Methods: addObserver

0
package observer.weatherobservable; 
 
import java.util.Observable; 
import java.util.Observer; 
 
public class ForecastDisplay implements Observer, DisplayElement {
    private float currentPressure = 29.92f;
    private float lastPressure;
 
    public ForecastDisplay(Observable observable) {
        observable.addObserver(this);
    } 
 
    public void update(Observable observable, Object arg) {
        if (observable instanceof WeatherData) {
            WeatherData weatherData = (WeatherData) observable;
            lastPressure = currentPressure;
            currentPressure = weatherData.getPressure();
            display(); 
        } 
    } 
 
    public void display() { 
        System.out.print("Forecast: ");
        if (currentPressure > lastPressure) {
            System.out.println("Improving weather on the way!");