Button triggered repaint() not working while call the function directly works fine

Question

I was creating an animation using recursion showing the process of Hanoi Tower. Here is my complete code, my question is when I using main to call the move() function, everything works fine, but when I tried to use a button, it does not work. Console output indicating the move() does getting called but the window does not get refreshed. Really got stuck here, Help much appreciated.

public class TowerOfHanoi{

//empty constructor, just for calling initializing methods
public TowerOfHanoi(){

}

private int numberOfLayers;

private Object[] towerA;
private Object[] towerB;
private Object[] towerC;

public int towerHeightOf(Object[] theTower){
    int result =0;
    for(Object current: theTower){
        if(current != null){
            result++;
        }
    }
    return result;
}


// initialize the arrays that holds the integer that represent the plate in tower
public void setLayerNbr(int layerNbr){
    this.numberOfLayers = layerNbr;
    this.moveCount = 0;

    towerA = new Object[numberOfLayers];
    towerB = new Object[numberOfLayers];
    towerC = new Object[numberOfLayers];

    //initialize the tower A
    for(int i=0; i< numberOfLayers; i++){
        towerA[i] = new Integer(layerNbr--);
    }
}

//these are the plate shifting method
//return the top most element of the tower
//warning, you are not only get the top plate, but remove it from the original racket as well
//specifications is the hardest stuff
@SuppressWarnings("unchecked")
public T getTopPlate(Object[] tower){
    Object lastElement = null;
    if(tower[tower.length-1] != null){
        lastElement = tower[tower.length-1];
    }
    for(int i=tower.length-1; i>-1; i--){
        if(tower[i] != null){
            lastElement = tower[i];
            tower[i] = null;
            break;
        }
    }
    return (T) lastElement;
}

// add a plate to a tower
public void addToTop(T currentPlate, Object[] targetTower){
    for(int i=0; i< numberOfLayers; i++){
        if(targetTower[i] == null){
            targetTower[i] = currentPlate;
            return;
        }
    }
}

// move the top plate from one to another
public void movePlate(Object[] originalTower, Object[] targetTower){
    addToTop(getTopPlate(originalTower), targetTower);
}

public Object[] getTowerByName(char name){
    Object[] result = null;
    switch(name){
    case 'A':
        result = towerA;
        break;

    case 'B':
        result = towerB;
        break;

    case 'C':
        result = towerC;
        break;
    default:
        break;

    }
    return result;
}

public void showTower(char name){
    Object[] currentTower = getTowerByName(name);
    for(int i=currentTower.length-1; i>-1; i--){
        if(currentTower[i] != null){
            System.out.println(currentTower[i].toString());
        }else{
            return;
        }
    }
}

/**
 * in most scenarios, nested components plus layout manager can achieve what you want
 */

private int moveCount;

///////
///////
///////
///////



private JFrame windowFrame; // top level container

private JPanel promptPanel; // contains the following two panels
private JLabel messageLabel;
private JLabel moveCountLabel;

private JPanel animationPanel;

private JPanel bottomeStaticPanel;// contains the following two panels

private JPanel buttonPanel; // contains the following
private JButton startBtn;
private JButton pauseBtn;
private JButton quitBtn;

private JPanel racketPanel;         // contains the following 3 panels, using grid panel
private JLabel aLabel = new JLabel("A");
private JLabel bLabel = new JLabel("B");
private JLabel cLabel = new JLabel("C");



//display the static background of the window
public void display(){

    windowFrame = new JFrame("Tower of Hanoi");
    windowFrame.setSize(1200, 700);
    Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
    windowFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    windowFrame.setBackground(Color.white);
    Container frameContainer = windowFrame.getContentPane();

    //set up the prompt panel
    promptPanel = new JPanel(new BorderLayout());
    messageLabel = new JLabel("Click \"Start\" to see the move!                          ");
    moveCountLabel = new JLabel("Moves Count: "+ moveCount+"    ");
    Font messageFont = new Font(Font.SANS_SERIF, Font.BOLD, 20);
    Font moveCountFont = new Font(Font.DIALOG, Font.BOLD, 15);
    messageLabel.setFont(messageFont);
    moveCountLabel.setFont(moveCountFont);
    messageLabel.setHorizontalAlignment(SwingConstants.CENTER);
    moveCountLabel.setHorizontalAlignment(SwingConstants.LEFT);
    promptPanel.add(messageLabel,BorderLayout.CENTER);
    promptPanel.add(moveCountLabel,BorderLayout.EAST);

    //set up the animation panel
    // todo: back ground color to be changed
    animationPanel = new JPanel();
    animationPanel.setPreferredSize(new Dimension(1200, 700));
    animationPanel.setBackground(Color.lightGray);
    animationPanel.setLayout(new BorderLayout());


    //set up the racket panel 
    aLabel = new JLabel("Tower A");
    bLabel = new JLabel("Tower B");
    cLabel = new JLabel("Tower C");
    Font racketFont = new Font(Font.SERIF, Font.BOLD, 17);
    aLabel.setFont(racketFont);
    bLabel.setFont(racketFont);
    cLabel.setFont(racketFont);
    aLabel.setHorizontalAlignment(SwingConstants.CENTER);
    bLabel.setHorizontalAlignment(SwingConstants.CENTER);
    cLabel.setHorizontalAlignment(SwingConstants.CENTER);

    racketPanel = new JPanel(new GridLayout(1, 3));
    racketPanel.add(aLabel);
    racketPanel.add(bLabel);
    racketPanel.add(cLabel);
    racketPanel.setBackground(Color.lightGray);

    //set up the button panel
    buttonPanel = new JPanel();
    startBtn = new JButton("Start");
    pauseBtn = new JButton("Pause");
    quitBtn = new JButton("Quit");


    startBtn.setEnabled(true);
    pauseBtn.setEnabled(false);
    quitBtn.setEnabled(true);

    buttonPanel.add(startBtn);
    buttonPanel.add(pauseBtn);
    buttonPanel.add(quitBtn);

    //set up the bottom panel
    bottomeStaticPanel = new JPanel(new BorderLayout());
    bottomeStaticPanel.add(racketPanel, BorderLayout.NORTH);
    bottomeStaticPanel.add(buttonPanel, BorderLayout.SOUTH);

    //set up the whole window frame
    frameContainer.add(promptPanel,BorderLayout.NORTH);
    frameContainer.add(animationPanel, BorderLayout.CENTER);
    frameContainer.add(bottomeStaticPanel, BorderLayout.SOUTH);

    //position the window frame on screen and display it
    windowFrame.setLocation(dim.width/2-windowFrame.getSize().width/2, dim.height/2-windowFrame.getSize().height/2);
    windowFrame.setVisible(true);

    ///*******////
    ///*******////
    ///*******////
    ///*******////
    //NOTE: since the constructor of the paintable panel needs animation panel's size, we need to make the JFrame render first
    PaintablePanel canvas = new PaintablePanel();// the panel actually do the animation

    animationPanel.add(canvas, BorderLayout.CENTER); //make the canvas take up the entire animation panel
    //Why make this nested structure, this way we can get size of the container.

    //this is vital, you must repaint after adding something to the container?
    //Other wise the change will not show up
    windowFrame.revalidate();
    try {
        Thread.sleep(1000);
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

public void setUpActionListeners(){
    startBtn.addActionListener(new startBtnListener());
    pauseBtn.addActionListener(new pauseBtnListener());
    quitBtn.addActionListener(new quitBtnListener());
}


@SuppressWarnings("serial")
class PaintablePanel extends JPanel{

    //dimension constant
    private final int HORIZONTAL_UNIT = animationPanel.getWidth()/1200; // 10 pixel per unit
    private final int PLATE_THICKNESS = animationPanel.getHeight()/(numberOfLayers+1);
    private final int BORDER_WIDTH = 2;
    private final int VERTICAL_BAR_STARTING_X = HORIZONTAL_UNIT*200-5;
    private final int BAR_HEIGHT =PLATE_THICKNESS*(numberOfLayers+1) ;
    private final int VERTICAL_BAR_STARTING_Y = animationPanel.getHeight()-BAR_HEIGHT;
    private final int PLATE_WIDTH_UNIT = 300*HORIZONTAL_UNIT/numberOfLayers;

    //color constant
    private final Color PLATE_COLOR = Color.CYAN;
    private final Color PLATE_BORDER_COLOR = Color.DARK_GRAY;
    private final Color VERTICAL_BAR_COLOR = Color.black;
    private final Color CHARACTER_COLOR = Color.blue;



    @Override
    public void paint(Graphics g){
        //todo : paint three towers according to its current status
        //paint the vertical bar;
        g.setColor(VERTICAL_BAR_COLOR);
        for(int i=0; i<3;i++){
            g.fillRect(VERTICAL_BAR_STARTING_X+i*400*HORIZONTAL_UNIT
                    ,VERTICAL_BAR_STARTING_Y
                    ,10
                    ,BAR_HEIGHT);
        }
        //debug
        int AHeight = towerHeightOf(towerA);
        int BHeight = towerHeightOf(towerB);
        int CHeight = towerHeightOf(towerC);



        for(int i=0; i= 1){
                return layerNbr;
            }else{
                JOptionPane.showMessageDialog(null,
                        "Number of layers must be an integer greater than 0",
                        "Try Again Please", JOptionPane.WARNING_MESSAGE);

                return this.getInput();
            }
        }
        return this.getInput();
    }

}

/////////////////
/////////////////
/////////////////



public static void main(String[] args){


    TowerOfHanoi theTower = new TowerOfHanoi<>();
    int layerNbr =theTower.getInput();
    theTower.setLayerNbr(layerNbr);

    theTower.display();
    theTower.setUpActionListeners();
    //let us use the button to call move now
    //theTower.move(layerNbr, 'A', 'C', 'B');

    return;

}

}

Button triggered repaint() not working while call the function directly works fine

Answers (1)

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