使用键盘移动图像 - Java

Question

I wanted to move my image using keyboard arrow keys. when I pressed the arrow keys it moves accordingly to the direction. However, I need to click on the image before able to move it. May I know how to edit the code such that I do not need to click on the image before able to move it? I would also like to know how to make the image appear from the left once it reaches right and vice versa.

My codes are :

    Collect.addKeyListener(new KeyAdapter() {
         public void keyPressed(KeyEvent ke)
         {   
         if(ke.getKeyCode() == KeyEvent.VK_LEFT)
             {
             Collect.setLocation(Collect.getX()-8,Collect.getY());
             repaint();
         }
         if(ke.getKeyCode() == KeyEvent.VK_RIGHT)
             {
             Collect.setLocation(Collect.getX()+8,Collect.getY());
             repaint();
         }
     }
 });
     Collect.addMouseListener(new MouseAdapter()
     {
     public void mouseClicked(MouseEvent me)
         {
         if(me.getClickCount() == 1)
             {
             boolean dd =  Collect.isOptimizedDrawingEnabled();
             boolean ff =  Collect.requestFocusInWindow();
             repaint();
         }
     }

 }); 

Answer 1

你看看KeyBindings ，否则你必须嵌套Image JComponent#setFocusable() ， 运动图像的例子

Answer 2

Collect.requestFocusInWindow();

requestFocusInWindow() ..

Requests that this Component get the input focus, if this Component's top-level ancestor is already the focused Window.

Make sure to call that only after the main window is visible and has the focus.

Answer 3

KeyListeners only work when the component which has the listener has focus . You are giving focus to what appears to be Collect by clicking on it. Then the listener works. You can add the listener to other things or force focus to remain on something like the outer frame by using a focus listener to regain focus whenever it is lost.