fix warnings

app/src/main/java/chess/App.java

@@ -12,7 +12,10 @@ public class App {
                     1 - Console
                     2 - Window
                     3 - 3D.""");
-        switch (new Scanner(System.in).nextLine()) {
+        Scanner scan = new Scanner(System.in);
+        String line = scan.nextLine();
+        scan.close();
+        switch (line) {
             case "1", "Console", "console":
                 ConsoleMain.main(args);
                 break;

app/src/main/java/chess/SwingMain.java

@@ -1,11 +1,8 @@
 package chess;
 
-import chess.ai.AI;
-import chess.ai.minimax.AlphaBetaAI;
 import chess.controller.CommandExecutor;
 import chess.controller.commands.NewGameCommand;
 import chess.controller.event.GameAdaptator;
-import chess.model.Color;
 import chess.model.Game;
 import chess.pgn.PgnExport;
 import chess.view.audio.GameAudio;

app/src/main/java/chess/view/simplerender/Window.java

@@ -74,15 +74,15 @@ public class Window extends JFrame implements GameListener {
 	}
 
 	private void buildButtons(JPanel bottom) {
-		castlingButton.addActionListener((event) -> {
+		castlingButton.addActionListener((_) -> {
 			sendCommand(new CastlingCommand(false));
 		});
 
-		bigCastlingButton.addActionListener((event) -> {
+		bigCastlingButton.addActionListener((_) -> {
 			sendCommand(new CastlingCommand(true));
 		});
 
-		undoButton.addActionListener((event) -> {
+		undoButton.addActionListener((_) -> {
 			sendCommand(new UndoCommand());
 		});