Files
design-patterns/03-behavioral/observer/AlertObserver.java

23 lines
830 B
Java

package observer;
/** Fires an alert when the price changes by more than a threshold % */
public class AlertObserver implements StockObserver {
private final String name;
private final double thresholdPercent;
public AlertObserver(String name, double thresholdPercent) {
this.name = name;
this.thresholdPercent = thresholdPercent;
}
@Override
public void onPriceChanged(String ticker, double oldPrice, double newPrice) {
double change = Math.abs((newPrice - oldPrice) / oldPrice * 100);
if (change >= thresholdPercent) {
System.out.printf(" [ALERT:%s] %s moved %.1f%% — ALERT TRIGGERED%n", name, ticker, change);
} else {
System.out.printf(" [Alert:%s] %s moved %.1f%% — within threshold%n", name, ticker, change);
}
}
}