вроде закончил

src/FrameBattleship.java

@@ -7,7 +7,7 @@ import java.io.IOException;
 import java.util.Random;
 public class FrameBattleship extends JFrame {
     private DrawingBattleship drawingBattleship;
-    private final JComponent pictureBox;
+    private JComponent pictureBox;
     public FrameBattleship() throws IOException {
         super("Линкор");
         setSize(new Dimension(900,500));