Fixes some behavior regarding backups

Makes sure to only proceed with backups if a valid path is given
Makes the backup run in its own thread to prevent the software from locking up
Makes sure only one backup can be running at once

src/main/java/net/knarcraft/minecraftserverlauncher/userinterface/ServerLauncherGUI.java

@@ -33,7 +33,7 @@ import static net.knarcraft.minecraftserverlauncher.utility.CommonFunctions.getR
  */
 public class ServerLauncherGUI extends MessageHandler implements ActionListener, GUI {
 
-    private final JLabel lblStatuslabel = new JLabel("Servers are stopped");
+    private final JLabel lblStatusLabel = new JLabel("Servers are stopped");
     private final ServerLauncherController controller;
     private Map<String, String> textStrings;
     private Tray applicationTray;
@@ -101,7 +101,7 @@ public class ServerLauncherGUI extends MessageHandler implements ActionListener,
 
     @Override
     public void setStatus(String text) {
-        this.lblStatuslabel.setText(text);
+        this.lblStatusLabel.setText(text);
         this.logMessage(text);
     }
 
@@ -243,11 +243,11 @@ public class ServerLauncherGUI extends MessageHandler implements ActionListener,
         panelBasic.add(profiles);
         profiles.addActionListener(this);
 
-        sl_panel.putConstraint(SpringLayout.NORTH, lblStatuslabel, 6, SpringLayout.SOUTH, addProfileButton);
-        sl_panel.putConstraint(SpringLayout.SOUTH, lblStatuslabel, -10, SpringLayout.SOUTH, panelBasic);
-        sl_panel.putConstraint(SpringLayout.WEST, lblStatuslabel, 10, SpringLayout.WEST, panelBasic);
-        sl_panel.putConstraint(SpringLayout.EAST, lblStatuslabel, -10, SpringLayout.EAST, panelBasic);
-        panelBasic.add(lblStatuslabel);
+        sl_panel.putConstraint(SpringLayout.NORTH, lblStatusLabel, 6, SpringLayout.SOUTH, addProfileButton);
+        sl_panel.putConstraint(SpringLayout.SOUTH, lblStatusLabel, -10, SpringLayout.SOUTH, panelBasic);
+        sl_panel.putConstraint(SpringLayout.WEST, lblStatusLabel, 10, SpringLayout.WEST, panelBasic);
+        sl_panel.putConstraint(SpringLayout.EAST, lblStatusLabel, -10, SpringLayout.EAST, panelBasic);
+        panelBasic.add(lblStatusLabel);
 
         addServerButton = new JButton("Add server");
         sl_panel.putConstraint(SpringLayout.NORTH, addServerButton, 0, SpringLayout.NORTH, startServerButton);
@@ -314,7 +314,7 @@ public class ServerLauncherGUI extends MessageHandler implements ActionListener,
     @Override
     public void actionPerformed(ActionEvent e) {
         Object actionSource = e.getSource();
-        //Registers actions on the main tab
+        //Register actions on the main tab
         handleMainTabButtons(actionSource);
     }
 
@@ -333,7 +333,8 @@ public class ServerLauncherGUI extends MessageHandler implements ActionListener,
         } else if (actionSource == addServerButton) {
             addServer();
         } else if (actionSource == backupButton) {
-            CommonFunctions.backup(this);
+            //Run backup in its own thread to prevent locking up
+            Executors.newSingleThreadExecutor().execute(() -> CommonFunctions.backup(this));
         } else if (actionSource == addProfileButton) {
             controller.addProfile(JOptionPane.showInputDialog("Profile name: "));
             updateProfiles();

src/main/java/net/knarcraft/minecraftserverlauncher/utility/CommonFunctions.java

@@ -36,6 +36,7 @@ import java.util.Scanner;
 public final class CommonFunctions {
 
     private static final String filesDirectory = Main.getApplicationWorkDirectory() + File.separator + "files";
+    private static boolean backupRunning = false;
 
     /**
      * Creates all folders necessary for tests and normal operation
@@ -53,7 +54,7 @@ public final class CommonFunctions {
      * @param folder <p>The folder to create</p>
      * @throws FileNotFoundException <p>If unable to create the folder</p>
      */
-    protected static void createFolder(File folder) throws FileNotFoundException {
+    public static void createFolder(File folder) throws FileNotFoundException {
         if (!folder.exists()) {
             if (!folder.mkdirs()) {
                 throw new FileNotFoundException("Cannot create necessary directory.");
@@ -298,8 +299,21 @@ public final class CommonFunctions {
     /**
      * Copies all server directories to a folder specified by the user.
      */
-    public static void backup(GUI gui) {
+    public synchronized static void backup(GUI gui) {
+        if (backupRunning) {
+            return;
+        } else {
+            backupRunning = true;
+        }
+
+        //Get the folder to save the backed up files in
         File path = gui.askForDirectory("Backup folder");
+        if (path == null || !path.isDirectory()) {
+            backupRunning = false;
+            return;
+        }
+
+        gui.setStatus("Backup running...");
         for (Collection collection : Main.getController().getCurrentProfile().getCollections()) {
             //Ignore disabled and invalid servers
             if (collection.getServer().getPath().equals("") || !collection.getServer().isEnabled()) {
@@ -312,6 +326,7 @@ public final class CommonFunctions {
             File destinationFolder = new File(path, name);
             //Create child folders
             if (!destinationFolder.exists() && !destinationFolder.mkdirs()) {
+                backupRunning = false;
                 throw new IllegalArgumentException("Unable to create necessary sub-folder in the backup folder");
             }
             //Backup
@@ -319,9 +334,11 @@ public final class CommonFunctions {
                 CommonFunctions.copyFolder(gui, srcFolder, destinationFolder);
             } catch (IOException e) {
                 e.printStackTrace();
+                backupRunning = false;
             }
         }
         gui.setStatus("Backup finished");
+        backupRunning = false;
     }
 
     /**