Simplified TzevaAdomNotifier request logic

src/main/java/dte/tzevaadomapi/alertsource/AlertSource.java

@@ -10,9 +10,9 @@
 public interface AlertSource
 {
 	/**
-	 * Returns the most recent {@link Alert} that happened in Israel.
+	 * Returns the most recent {@link Alert} that happened in Israel
 	 * 
-	 * @return Either the alert, or {@link #NO_RESULT} if one wasn't found.
+	 * @return The alert, or null if no info was found.
 	 * @throws Exception If an exception happened while gathering the alert.
 	 */
 	Alert getMostRecentAlert() throws Exception;
@@ -21,16 +21,8 @@ public interface AlertSource
 	 * Returns all the alerts that happened since the provided {@code alert}.
 	 * 
 	 * @param alert The 'minimum' alert.
-	 * @return The alerts list, or an empty result if there was no Tzeva Adom afterwards.
-	 * @throws Exception iF an exception happened while gathering the alerts.
+	 * @return The alerts list, or an empty result if there was no Tzeva Adom afterward.
+	 * @throws Exception If an exception happened while gathering the alerts.
 	 */
 	Deque<Alert> getSince(Alert alert) throws Exception;
-
-
-	/**
-	 * This object signals when {@link #getMostRecentAlert()} couldn't find an alert to return, and no exceptions occurred.
-	 * <p>
-	 * This is addressed because <i>Pikud Ha'oref</i> returns an empty JSON if no Tzeva Adom happened in the last 24 hours.
-	 */
-	Alert NO_RESULT = null;
 }

src/main/java/dte/tzevaadomapi/alertsource/PHOAlertSource.java

@@ -1,5 +1,6 @@
 package dte.tzevaadomapi.alertsource;
 
+import java.io.IOException;
 import java.lang.reflect.Type;
 import java.net.Proxy;
 import java.net.URL;
@@ -79,12 +80,19 @@ public Deque<Alert> getSince(Alert alert) throws Exception
 		});
 	}
 
-	//starts reading the JSON list posted by Pikud Ha'oref, and applies the function on it
-	private <T> T beginReadingArray(CheckedFunction<JsonReader, T> resultParser) 
+	//starts reading the JSON array posted by Pikud Ha'oref, and applies the function on it
+	private <T> T beginReadingArray(CheckedFunction<JsonReader, T> resultParser)
 	{
 		try(JsonReader reader = new JsonReader(newInputStreamReader()))
 		{
-			reader.beginArray();
+			try
+			{
+				reader.beginArray();
+			}
+			catch(IOException exception)
+			{
+				return null;
+			}
 
 			return resultParser.apply(reader);
 		}

src/main/java/dte/tzevaadomapi/notifier/TzevaAdomNotifier.java

@@ -14,7 +14,7 @@
 import dte.tzevaadomapi.alertsource.PHOAlertSource;
 import dte.tzevaadomapi.exceptionhandler.LimitedExceptionHandler;
 import dte.tzevaadomapi.listener.TzevaAdomListener;
-import dte.tzevaadomapi.utils.CheckedSupplier;
+import dte.tzevaadomapi.utils.CheckedFunction;
 
 /**
  * Notifies registered listeners immediately upon a <b>Tzeva Adom</b>.
@@ -49,13 +49,13 @@ public CompletableFuture<Void> listenAsync()
 		return CompletableFuture.runAsync(() -> 
 		{
 			//start with the most recent alert
-			this.mostRecentAlert = requestMostRecentAlert();
+			this.mostRecentAlert = requestFromSource(AlertSource::getMostRecentAlert);
 
 			while(true)	
 			{
-				Deque<Alert> newAlerts = requestFromSource(() -> this.alertSource.getSince(this.mostRecentAlert));
-				
-				//if there are no new alerts - it's not Tzeva Adom
+				Deque<Alert> newAlerts = requestFromSource(source -> source.getSince(this.mostRecentAlert));
+
+				//wait until a terror organization decides to launch rockets
 				if(newAlerts.isEmpty()) 
 					continue;
 
@@ -88,31 +88,22 @@ public TzevaAdomHistory getHistory()
 	{
 		return this.history;
 	}
-
-	private Alert requestMostRecentAlert() 
-	{
-		Alert alert;
-
-		//wait until a terror organization decides to launch rockets
-		do 
-		{
-			alert = requestFromSource(this.alertSource::getMostRecentAlert);
-		}
-		while(alert == AlertSource.NO_RESULT);
-
-		return alert;
-	}
 
-	private <T> T requestFromSource(CheckedSupplier<T> resultFactory)
+	private <T> T requestFromSource(CheckedFunction<AlertSource, T> request)
 	{
 		while(true)
 		{
 			try 
 			{
 				//sleep the defined delay
 				TimeUnit.MILLISECONDS.sleep(this.requestDelay.toMillis());
-
-				return resultFactory.get();
+
+				T result = request.apply(this.alertSource);
+
+				if(result == null)
+					continue;
+
+				return result;
 			}
 			catch(Exception exception) 
 			{