Question

Okay so I am pretty much doing a crash course through creating a java application and am having an issue with executing an action. The program is the 15 puzzle, the game where you slide one piece at a time and try to get all numbers in order, so I allow for an ‘Auto’ mode option that will solve the board for the user once clicked. So my code reads the solution from a text file which is working fine just none of the ‘squares’ (JButtons) move when I click the auto button. So i am not sure if I just don’t understand the action even process completely or not. heres my code, I can supply more of it if necessary.

if (e.getSource() == ctrButtons[0]) {
      System.out.println("Auto Mode started\n");
      Scanner s = null;

      try {
        s = new Scanner(new BufferedReader(new FileReader("move_list.txt")));
        int count = 0;
        while (s.hasNext()) {
          //Cycle through to move in move_list
          if (count != 18) {
            s.next();
            count+=1;
          }
          else {
            int cur_move = Integer.parseInt(s.next());
            count = 0;
            /*Use cur_move to move blank space accordingly
             *UP------------3
             *LEFT----------2
             *RIGHT---------1
             *DOWN----------0
            */
            int zero_index = -1;
            for (int j=0; j<jbnButtons.length; j++) {
              if (Integer.parseInt(jbnButtons[j].getText()) == 0) {
                zero_index = j;
                break;
              }
            }

            Point zero = jbnButtons[zero_index].getLocation();

            //Check if move is up
            if (cur_move == 3) {
              Point next = jbnButtons[zero_index-4].getLocation();
              jbnButtons[zero_index].setLocation(next);
              jbnButtons[zero_index-4].setLocation(zero);
            }
//Check if move is left
                else if (cur_move == 2) {
                  Point next = jbnButtons[zero_index-1].getLocation();
                  jbnButtons[zero_index].setLocation(next);
                  jbnButtons[zero_index-1].setLocation(zero);
                }

            //Check if move is right
            else if (cur_move == 1) {
              Point next = jbnButtons[zero_index+1].getLocation();
              jbnButtons[zero_index].setLocation(next);
              jbnButtons[zero_index+1].setLocation(zero);
            }

            //Check if move is down
            else {
              System.out.println("Current move = 0");
              Point next = jbnButtons[zero_index+4].getLocation();
              jbnButtons[zero_index].setLocation(next);
              jbnButtons[zero_index+4].setLocation(zero);
            }

          }
        }
      }

So my code executes when I click the ‘Auto’ button and I was printing output to the screen to see if it was looping through the code which it was, just none of the buttons move each time through the loop. Any ideas??

Answer 1

You code is executing on the Event Dispatch Thread. The GUI can’t repaint itself until the code finishes executing, so you won’t see the intermediate steps only the final location of each component.

Read tje section from the Swing tutorial on Concurrency for a more complete explanation.

Maybe you should use a Swing Timer (the tutorial also has a section on this). Each time the Timer fire you do the next move.