Changes based on comments

Author: AustinShalit

core/src/main/java/edu/wpi/grip/core/FileManager.java

@@ -1,7 +1,7 @@
 package edu.wpi.grip.core;
 
 /**
- * Defines what methods a FileManager implementation must implement.
+ * A FileManager saves images to disk.
  */
 public interface FileManager {
 

core/src/main/java/edu/wpi/grip/core/GripFileManager.java

@@ -25,18 +25,19 @@ public class GripFileManager implements FileManager {
 
   @Override
   public void saveImage(byte[] image, String fileName) {
-    checkNotNull(image);
-    checkNotNull(fileName);
+    checkNotNull("An image was not provided to the FileManager", image);
+    checkNotNull("A filename was not provided to the FileManager", fileName);
 
     File file = new File(IMAGE_DIRECTORY, fileName);
-    Runnable runnable = () -> {
+    Thread thread = new Thread(() -> {
       try {
         IMAGE_DIRECTORY.mkdirs(); // If the user deletes the directory
         Files.write(image, file);
       } catch (IOException ex) {
         logger.log(Level.WARNING, ex.getMessage(), ex);
       }
-    };
-    new Thread(runnable).start();
+    });
+    thread.setDaemon(true);
+    thread.start();
   }
 }

core/src/main/java/edu/wpi/grip/core/operations/composite/SaveImageOperation.java

@@ -70,7 +70,8 @@ private enum FileTypes {
 
   @SuppressWarnings("JavadocMethod")
   public SaveImageOperation(InputSocket.Factory inputSocketFactory,
-                            OutputSocket.Factory outputSocketFactory, FileManager fileManager) {
+                            OutputSocket.Factory outputSocketFactory,
+                            FileManager fileManager) {
     this.fileManager = fileManager;
 
     inputSocket = inputSocketFactory.create(inputHint);