Better Serialization

src/com/t_oster/liblasercut/TimeIntensiveOperation.java

 /**
- * This file is part of VisiCut.
- * Copyright (C) 2012 Thomas Oster <thomas.oster@rwth-aachen.de>
- * RWTH Aachen University - 52062 Aachen, Germany
- * 
- *     VisiCut is free software: you can redistribute it and/or modify
- *     it under the terms of the GNU Lesser General Public License as published by
- *     the Free Software Foundation, either version 3 of the License, or
- *     (at your option) any later version.
- * 
- *    VisiCut is distributed in the hope that it will be useful,
- *     but WITHOUT ANY WARRANTY; without even the implied warranty of
- *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *     GNU Lesser General Public License for more details.
- * 
- *     You should have received a copy of the GNU Lesser General Public License
- *     along with VisiCut.  If not, see <http://www.gnu.org/licenses/>.
- **/
+ * This file is part of VisiCut. Copyright (C) 2012 Thomas Oster
+ * <thomas.oster@rwth-aachen.de> RWTH Aachen University - 52062 Aachen, Germany
+ *
+ * VisiCut is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option) any
+ * later version.
+ *
+ * VisiCut is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ * A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with VisiCut. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
 package com.t_oster.liblasercut;
 
 import java.util.LinkedList;
 import java.util.List;
 
 /**
- * This class is for easy support for Progress Listeners
- * just extend this class and use the fireProgressChanged
- * and fireTaskNameChanged method.
- * 
+ * This class is for easy support for Progress Listeners just extend this class
+ * and use the fireProgressChanged and fireTaskNameChanged method.
+ *
  * @author Thomas Oster <thomas.oster@rwth-aachen.de>
  */
 public abstract class TimeIntensiveOperation
 {
 
-  private List<ProgressListener> listeners = new LinkedList<ProgressListener>();
+  private List<ProgressListener> listeners = null;
+
+  private List<ProgressListener> getListeners()
+  {
+    if (listeners == null)
+    {
+      listeners = new LinkedList<ProgressListener>();
+    }
+    return listeners;
+  }
 
   public void addProgressListener(ProgressListener l)
   {
-      listeners.add(l);
+    getListeners().add(l);
   }
 
   public void removeProgressListener(ProgressListener l)
   {
-    listeners.remove(l);
+    getListeners().remove(l);
   }
 
   public void fireProgressChanged(int progress)
   {
-    for (ProgressListener l : listeners)
+    for (ProgressListener l : getListeners())
     {
       l.progressChanged(this, progress);
     }
@@ -53,15 +61,17 @@ public abstract class TimeIntensiveOperation
 
   public void fireTaskChanged(String name)
   {
-    for (ProgressListener l : listeners)
+    for (ProgressListener l : getListeners())
     {
       l.taskChanged(this, name);
     }
   }
-
   private int progress = 0;
-  protected void setProgress(int progress){
-    if (progress != this.progress){
+
+  protected void setProgress(int progress)
+  {
+    if (progress != this.progress)
+    {
       this.progress = progress;
       this.fireProgressChanged(this.progress);
     }