Adapt to review #20

src/main/scala/de/retest/guistatemachine/api/GuiStateMachineSerializer.scala

@@ -8,6 +8,6 @@ trait GuiStateMachineSerializer {
 }
 
 object GuiStateMachineSerializer {
-  def javaObjectStream(guiStateMachine: GuiStateMachine): GuiStateMachineSerializer = GuiStateMachineJavaObjectStreamSerializer(guiStateMachine)
-  def gml(guiStateMachine: GuiStateMachine): GuiStateMachineSerializer = GuiStateMachinGMLSerializer(guiStateMachine)
+  def javaObjectStream(guiStateMachine: GuiStateMachine): GuiStateMachineSerializer = new GuiStateMachineJavaObjectStreamSerializer(guiStateMachine)
+  def gml(guiStateMachine: GuiStateMachine): GuiStateMachineSerializer = new GuiStateMachinGMLSerializer(guiStateMachine)
 }

src/main/scala/de/retest/guistatemachine/api/impl/serialization/GuiStateMachinGMLSerializer.scala

@@ -6,7 +6,7 @@ import de.retest.guistatemachine.api.{GuiStateMachine, GuiStateMachineSerializer
 import de.retest.recheck.ui.descriptors.SutState
 import org.jgrapht.graph.DirectedPseudograph
 
-case class GuiStateMachinGMLSerializer(guiStateMachine: GuiStateMachine) extends GuiStateMachineSerializer {
+class GuiStateMachinGMLSerializer(guiStateMachine: GuiStateMachine) extends GuiStateMachineSerializer {
 
   type GraphType = DirectedPseudograph[SutState, GraphActionEdge]
 
@@ -33,10 +33,10 @@ case class GuiStateMachinGMLSerializer(guiStateMachine: GuiStateMachine) extends
     // write to file
     val outputFile = new File(filePath)
     val output = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(outputFile), "utf-8"))
-    try { writer.export(output, toDraw) } finally { if (output != null) { output.close() } }
+    try { writer.export(output, toDraw) } finally { output.close() }
   }
 
-  override def load(filePath: String): Unit = throw new RuntimeException("Loading GML is not supported.")
+  override def load(filePath: String): Unit = throw new UnsupportedOperationException("Loading GML is not supported.")
 
   private def createGraph(): GraphType = {
     val graph = new GraphType(classOf[GraphActionEdge])

src/main/scala/de/retest/guistatemachine/api/impl/serialization/GuiStateMachineJavaObjectStreamSerializer.scala

@@ -5,19 +5,21 @@ import java.io.{FileInputStream, FileOutputStream, ObjectInputStream, ObjectOutp
 import de.retest.guistatemachine.api.impl.GuiStateMachineImpl
 import de.retest.guistatemachine.api.{GuiStateMachine, GuiStateMachineSerializer}
 
-case class GuiStateMachineJavaObjectStreamSerializer(guiStateMachine: GuiStateMachine) extends GuiStateMachineSerializer {
+class GuiStateMachineJavaObjectStreamSerializer(guiStateMachine: GuiStateMachine) extends GuiStateMachineSerializer {
 
   /**
-    * Stores the state machine on the disk.
-    * Persistence can be useful when the state machines become quite big and the generation/modification is interrupted
-    * and continued later.
+    * Stores the state machine on the disk. Persistence can be useful when the state machines become quite big and the
+    * generation/modification is interrupted and continued later.
     *
     * @param filePath The file which the state machine is stored into.
     */
   override def save(filePath: String): Unit = {
     val oos = new ObjectOutputStream(new FileOutputStream(filePath))
-    oos.writeObject(guiStateMachine)
-    oos.close()
+    try {
+      oos.writeObject(guiStateMachine)
+    } finally {
+      oos.close()
+    }
   }
 
   /**
@@ -26,10 +28,12 @@ case class GuiStateMachineJavaObjectStreamSerializer(guiStateMachine: GuiStateMa
     * @param filePath The file which the state machine is loaded from.
     */
   override def load(filePath: String): Unit = {
-    guiStateMachine.clear()
     val ois = new ObjectInputStream(new FileInputStream(filePath))
-    val readStateMachine = ois.readObject.asInstanceOf[GuiStateMachineImpl]
-    ois.close()
-    guiStateMachine.assignFrom(readStateMachine)
+    try {
+      val readStateMachine = ois.readObject.asInstanceOf[GuiStateMachineImpl]
+      guiStateMachine.assignFrom(readStateMachine)
+    } finally {
+      ois.close()
+    }
   }
 }