refactor(build): Fix Resources issue in .jar

src/main/java/com/amirhn/GUI/ChessController.java

@@ -12,6 +12,8 @@
 import com.amirhn.Pieces.Piece;
 import java.io.File;
 import java.io.IOException;
+import java.net.URL;
+import java.util.Objects;
 import javax.sound.sampled.*;
 import javax.swing.*;
 
@@ -76,9 +78,10 @@ private void playMoveSound(Move move) {
     } else {
       soundPath = Constants.MoveSoundPath;
     }
+    URL soundURL = getClass().getResource(soundPath);
     AudioInputStream audioInputStream = null;
     try {
-      audioInputStream = AudioSystem.getAudioInputStream(new File(soundPath).getAbsoluteFile());
+      audioInputStream = AudioSystem.getAudioInputStream(Objects.requireNonNull(soundURL));
     } catch (UnsupportedAudioFileException | IOException e) {
       e.printStackTrace();
     }

src/main/java/com/amirhn/GUI/Components/PieceImageIcon.java

@@ -2,18 +2,17 @@
 
 import com.amirhn.GUI.Constants;
 import javax.swing.*;
+import java.util.Objects;
 
 /** The type Piece image icon. */
 public class PieceImageIcon extends ImageIcon {
-  private static final String DefaultPath = Constants.PieceImageDirectory;
-
   /**
    * Instantiates a new Piece image icon.
    *
    * @param color the color
    * @param typeLetter the type letter
    */
   public PieceImageIcon(String color, char typeLetter) {
-    super(DefaultPath + "/" + color.toLowerCase().charAt(0) + typeLetter + ".png");
+    super(Objects.requireNonNull(PieceImageIcon.class.getResource(Constants.PieceImageDirectory + "/" + color.toLowerCase().charAt(0) + typeLetter + ".png")));
   }
 }

src/main/java/com/amirhn/GUI/Constants.java

@@ -29,10 +29,10 @@ public class Constants {
   public static final String GameTitle = "Chess";
 
   /** The constant PieceImageDirectory. */
-  public static final String PieceImageDirectory = "png";
+  public static final String PieceImageDirectory = "/png";
 
   /** The constant SoundDirectory. */
-  public static final String SoundDirectory = "sound";
+  public static final String SoundDirectory = "/sound";
 
   /** The constant MoveSoundPath. */
   public static final String MoveSoundPath = Constants.SoundDirectory + "/" + "move.wav";