memory game graphics java

I'm coding a program that is a 4x4 memory game. Within these 16 boxes will be a pair of integers from 0-7. I have all of that already randomized and coded correctly. Now I'm trying to figure out how to pair the colors with the corresponding integers each time the mouse clicks over the box.

Here most of the code. I know the logic for this game isn't started yet, but I'm more focused on the displayHit method and setColor method right now. Just posting the whole code because maybe I messed up somewhere else.

/*Sets the background of your memory board to black*/
public void init() 
{
    setSize(400,400);
    setBackground(Color.BLACK);
    buildBoard(4);

}   
/*This is main in java applets
    You may need to add (not change) a couple things in this method
 */
public void paint(Graphics canvas)
{
    if(firstRun) //for the first run we need to build our random board
    {

        print2DArray(board);
        buildBoard(4);
        firstRun = false;
    } 
    else // once our board is built we will display the game
    {
        displayGame(canvas);
        if (mouseClicked) // if the mouse has been clicked
        {
            displayHit(canvas);//find which box the user clicked
            mouseClicked = false;
        }
    }
}

/*
    DO NOT change this method
    determines if the mouse has been pressed
    sets x and y Mouse to the location of the mouse arrow
    redraws the image
 */
public boolean mouseDown(Event e, int x, int y ) 
{
    mouseClicked = true; 
    xMouse = x;
    yMouse = y;
    repaint();
    return true;
}

/*DO NOT change this method
    redraws the scene
 */
public void update ( Graphics g ) 
{
    paint(g);

}

/*
    pre: none
    post: build an array that holds the memory values for a board of size x size
    the board will hold two of each int from 0 to size randomly placed in the array
 */


public void buildBoard(int s)

{
    int a = 4;
    for (int row = 0; row < a; row++)
        for (int column = 0; column < a; column++)
        {

            board[row][column] = count++ % 8;
        }
    for(int row = 0; row < 4; row++)

        for(int column = 0; column < 4; column ++) 
        {
            int x = (int)Math.floor(Math.random()*4);
            int y = (int)Math.floor(Math.random()*4);
            temp = board[row][column];
            board[row][column] = board[x][y];
            board[x][y] = temp;


        }
}
public static void print2DArray(int[][] arr)
{
    for (int row = 0; row < arr.length; row++)
    {
        for (int col = 0; col < arr[row].length; col++)
        {
            System.out.print(arr[row][col] + " ");
        }
        System.out.println();
    }
}





public void displayGame(Graphics canvas)
{
    canvas.setColor(Color.WHITE);

    for(int i =0; i < 400; i+= WIDTH)
        for(int j = 0; j < 400; j+= WIDTH)
            canvas.drawRect(i, j, WIDTH, WIDTH);
}

/*
    Pre: xMouse and yMouse have been initialized
    Post: A circle is displayed in the correct box on the screen
    Currently the circle is displayed at the mouse location
 */
public void displayHit(Graphics g)
{
    buildBoard(temp);
    setColor(g);
    centerHit(xMouse, xMouse);
    g.fillOval(xMouse, yMouse, 40, 40);
}

public void setColor(Graphics g)
{

    switch(temp)
    {
    case 0: g.setColor(Color.RED);
    break;
    case 1: g.setColor(Color.GREEN);
    break;
    case 2: g.setColor(Color.BLUE);
    break;
    case 3: g.setColor(Color.ORANGE);
    break;
    case 4: g.setColor(Color.CYAN);
    break;
    case 5: g.setColor(Color.MAGENTA);
    break;
    case 6: g.setColor(Color.PINK);
    break;
    case 7: g.setColor(Color.YELLOW);
    break;
    }

}
public void centerHit(int centerX, int centerY)
{
    {
        if ((xMouse > 0) && (xMouse <=100))
            xMouse = 33;
        else if ((xMouse > 100) && (xMouse <=200))
            xMouse = 133;
        else if ((xMouse > 200) && (xMouse <=300))
            xMouse = 233;
        else if ((xMouse > 300) && (xMouse <=400))
            xMouse = 333;
    }
    {
        if ((yMouse > 0) && (yMouse <=100))
            yMouse = 33;
        else if ((yMouse > 100) && (yMouse <=200))
            yMouse = 133;
        else if ((yMouse > 200) && (yMouse <=300))
            yMouse = 233;
        else if ((yMouse > 300) && (yMouse <=400))
            yMouse = 333;
    }



}

}

From your code there is not much to see about what you did there,

but I guess you should try the following:

1)make sure you have a component say we call it cmp.

2)make sure every time the box is clicked cmp.repaint() is called

3)make sure to call the displayHit(g) function from within cmp's paintComponent(Graphics g)

that should do

Also, where is temp being manipulated?

this should be helpfull:

public class ColorChanger extends JFrame implements MouseListener {
    private Color c =  Color.black;
    private JPanel p = new JPanel () {
        public void paintComponent(Graphics g) {
            g.setColor(c );
            g.drawRect(100, 100, 100, 100);
        }

    };

    public  ColorChanger() {
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setPreferredSize(new Dimension(1024, 700));
        addMouseListener(this);
        this.getContentPane().add(p);
        pack();
        setVisible(true);
    }


    public static void main (String arg[]) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new ColorChanger();
            }
        });
    }
    @Override
    public void mouseClicked(MouseEvent arg0) {
        randomizeColor();
        p.repaint();

    }
    private void randomizeColor() {
        switch ((int)(3*Math.random())) {
        case 0:c=Color.red;return;
        case 1:c=Color.blue;return;
        case 2:c=Color.green;return;
        }
    }
    @Override
    public void mouseEntered(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }
    @Override
    public void mouseExited(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }
    @Override
    public void mousePressed(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }
    @Override
    public void mouseReleased(MouseEvent arg0) {
        // TODO Auto-generated method stub

    }

}