Java Swing Button Listeners无法正常工作

Question

I have two button listeners for game board using java swing.

A tetris grid is created initially and then addition functionality within each button listener.

I set the board up like so in my Play.java:

final TetrisGame g = new TetrisGame(11,1);
final BoardGraphics graphics = new BoardGraphics(TetrisBoard.BOARD_WIDTH, 40, g);

The button listeners are then created in the same Play.java:

graphics.btnStart.addActionListener(new ActionListener()
        {
           public void actionPerformed(ActionEvent e)
           {
              Action arc = p.getAction(g);
              g.update(arc);
              graphics.colours.clear();
              graphics.setColor(g.getBoard().getGrid());
              while (arc instanceof Store){
                  arc = p.getAction(g);
                  g.update(arc);
                  graphics.colours.clear();
                  graphics.setColor(g.getBoard().getGrid());
              }

             graphics.tiles.redraw();
             System.out.println();
             System.out.println(g.toString());
             System.out.println();
           }

        });


        graphics.btnAuto.addActionListener(new ActionListener()
        {
           public void actionPerformed(ActionEvent e)
           {

               while (!g.gameEnded()){
                  Action arc = p.getAction(g);
                  g.update(arc);
                  graphics.colours.clear();
                  graphics.setColor(g.getBoard().getGrid());
                  while (arc instanceof Store){
                      arc = p.getAction(g);
                      g.update(arc);
                      //graphics.colours.clear();
                      graphics.setColor(g.getBoard().getGrid());
                  }
                  graphics.tiles.redraw();
                  System.out.println();
                  System.out.println(g.toString());
                  System.out.println();
                  /*try {
                    Thread.sleep(1000);
                } catch (InterruptedException e1) {
                    // TODO Auto-generated catch block
                    e1.printStackTrace();
                }*/

               }

           }

        });

The btnStart works perfectly, pressing it once, painting the tetrisboard according to the next move given by AI agent.

I would like the btnAuto to play each move out without the user pressing btnStart to generate move until the end. However, my btnAuto does not paint anything on to the grid but the final state of the game, the finishing state.

Can anyone see why this might be not repainting the grid after each move is generated in the while loop?

Answer 1

Your while loop is being called on the Swing event thread and is thus preventing the the thread from doing its necessary actions including rendering the GUI and interacting with the user:

while (!g.gameEnded()){
  Action arc = p.getAction(g);

  // ....

}

I would use a Swing Timer here instead of a while (true) loop. Another option is to use a background thread, but since all you desire is a very simple game loop and don't need to run some long-running in the background, I think that this second option would be more complex with no additional benefit.

As an aside, I'm curious how you're doing your drawing and how you're getting your Graphics object to draw with. You're not calling getGraphics() on a component, are you?

---

Edit you state in a comment:

I currently have a class with a nested class that extends JPanel. The drawing of the grid and getGraphics() is done within the nested class.The parent class creates the component and sets the layout of the GUI as a whole

Don't get a Graphics object by calling getGraphics() on a GUI component as the Graphics object obtained will not persist. To see that this is so, simply minimize and then restore your application and tell me what happens to your graphics after doing this. You should do all of your drawing in the JPanel's paintComponent override. One option is to call getGraphics() on a BufferedImage and use it to draw to the BufferedImage, and then display the BufferedImage in the paintComponent override. If you use the second technique, don't forget to dispose of the BufferedImage's Graphics object after you are done using it so that you don't hog system resources.