From 5557030e0d1d1d88e323437dbcda7539efedd8b2 Mon Sep 17 00:00:00 2001
From: "J. Neugebauer" <ngb@helmholtz-bi.de>
Date: Mon, 11 Jul 2022 14:41:58 +0200
Subject: [PATCH] =?UTF-8?q?Delayed=20initialization=20auch=20f=C3=BCr=20Mu?=
 =?UTF-8?q?sic=20Klasse?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/main/java/schule/ngb/zm/media/Music.java | 43 ++++++++++++--------
 1 file changed, 27 insertions(+), 16 deletions(-)

diff --git a/src/main/java/schule/ngb/zm/media/Music.java b/src/main/java/schule/ngb/zm/media/Music.java
index 7b2fb73..1bd5640 100644
--- a/src/main/java/schule/ngb/zm/media/Music.java
+++ b/src/main/java/schule/ngb/zm/media/Music.java
@@ -1,5 +1,7 @@
 package schule.ngb.zm.media;
 
+import schule.ngb.zm.anim.Animation;
+import schule.ngb.zm.anim.AnimationListener;
 import schule.ngb.zm.events.EventDispatcher;
 import schule.ngb.zm.tasks.TaskRunner;
 import schule.ngb.zm.util.Log;
@@ -56,12 +58,7 @@ public class Music implements Audio {
 	 */
 	private float volume = 0.8f;
 
-	EventDispatcher<Audio, AudioListener> events;
-	{
-		events = new EventDispatcher<>();
-		events.registerEventType("start", (a,l) -> l.start(a));
-		events.registerEventType("stop", (a,l) -> l.stop(a));
-	}
+	EventDispatcher<Audio, AudioListener> eventDispatcher;
 
 	public Music( String source ) {
 		Validator.requireNotNull(source);
@@ -72,14 +69,6 @@ public class Music implements Audio {
 		return audioSource;
 	}
 
-	public void addListener( AudioListener listener ) {
-		events.addListener(listener);
-	}
-
-	public void removeListener( AudioListener listener ) {
-		events.removeListener(listener);
-	}
-
 	/**
 	 * {@inheritDoc}
 	 */
@@ -205,7 +194,7 @@ public class Music implements Audio {
 	private void stream() {
 		audioLine.start();
 		playing = true;
-		events.dispatchEvent("start", Music.this);
+		eventDispatcher.dispatchEvent("start", Music.this);
 
 		byte[] bytesBuffer = new byte[BUFFER_SIZE];
 		int bytesRead = -1;
@@ -232,7 +221,7 @@ public class Music implements Audio {
 
 		playing = false;
 		streamingStopped();
-		events.dispatchEvent("stop", Music.this);
+		eventDispatcher.dispatchEvent("stop", Music.this);
 	}
 
 	private boolean openLine() {
@@ -286,6 +275,28 @@ public class Music implements Audio {
 		}
 	}
 
+	public void addListener( AudioListener listener ) {
+		initializeEventDispatcher().addListener(listener);
+	}
+
+	public void removeListener( AudioListener listener ) {
+		initializeEventDispatcher().removeListener(listener);
+	}
+
+	/**
+	 * Interne Methode, um den Listener-Mechanismus zu initialisieren. Wird erst
+	 * aufgerufen, soblad sich auch ein Listener registrieren möchte.
+	 * @return
+	 */
+	private EventDispatcher<Audio, AudioListener> initializeEventDispatcher() {
+		if( eventDispatcher == null ) {
+			eventDispatcher = new EventDispatcher<>();
+			eventDispatcher.registerEventType("start", (a,l) -> l.start(a));
+			eventDispatcher.registerEventType("stop", (a,l) -> l.stop(a));
+		}
+		return eventDispatcher;
+	}
+
 	private static final Log LOG = Log.getLogger(Music.class);
 
 }