code cleanup

src/main/java/org/mansart/mongocount/Configuration.java

@@ -4,7 +4,7 @@
 import java.util.ArrayList;
 
 public final class Configuration {
-    private ArrayList<Listener> listeners = new ArrayList<>();
+    private final ArrayList<Listener> listeners = new ArrayList<>();
     private String host = "localhost";
     private int port = 27017;
     private String dbname = "";

src/main/java/org/mansart/mongocount/Counter.java

@@ -4,16 +4,14 @@
 import com.mongodb.DBCollection;
 import com.mongodb.MongoClient;
 
-import java.net.UnknownHostException;
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
 import java.util.Date;
 
 public final class Counter implements Configuration.Listener, Runnable {
     private static final DateFormat DATE_FORMAT = new SimpleDateFormat("HH:mm:ss");
-    private ArrayList<Listener> listeners = new ArrayList<>();
-    private MongoClient client = null;
+    private final ArrayList<Listener> listeners = new ArrayList<>();
     private Configuration configuration = null;
     private Thread thread = null;
 
@@ -88,7 +86,7 @@ public void run() {
                 this.notifyListenersOfCount(count);
                 Thread.sleep(this.configuration.getInterval() * 1000);
             }
-            if (this.client != null) this.client.close();
+            client.close();
         } catch (Exception e) {
             this.stop();
             this.notifyListenersOfCountError();

src/main/java/org/mansart/mongocount/gui/ConfigurationDialog.java

@@ -10,7 +10,7 @@
 import java.awt.event.WindowAdapter;
 import java.awt.event.WindowEvent;
 
-public final class ConfigurationDialog extends JDialog {
+final class ConfigurationDialog extends JDialog {
     private static final Color[] COLORS = new Color[] {
         Color.BLACK,
         Color.BLUE,