init tank project2

src/event_/BallMove.java

@@ -16,6 +16,7 @@ public class BallMove  extends JFrame{
         MyPanel myPanel = new MyPanel();
         this.add(myPanel);
         this.setSize(400,300);
+        this.addKeyListener(myPanel);
         this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         this.setVisible(true);
     }
@@ -28,7 +29,9 @@ class MyPanel extends JPanel implements KeyListener {
 
     @Override
     public void keyPressed(KeyEvent e) {
-
+        if(e.getKeyCode() == KeyEvent.VK_DOWN) {
+            System.out.println("按下了向下的按键");
+        }
     }
 
     @Override