带按钮的 Swing JPanel 无法重新绘制

Question

I am currently building a simple minesweeper game for a school project, in which every field is an instance of the Field class which inherits JButton. Here's (most of) the class in its current state:

public class Field extends JButton implements MouseListener {

    public Field() {
        super(" ");
        setFocusable(false);
        addMouseListener(this);
        setFont(new Font("sans serif", Font.PLAIN, 20));
    }

    @Override
    public void mouseClicked(MouseEvent me) {
        //...
    }

}

These fields then basically get added to a MineField object, which inherits JPanel. Here's the code for that, too:

class MineField extends JPanel {

    Field[][] fields;

    public MineField(int x, int y, int m) {
        fields = new Field[x][y];

        setLayout(new GridLayout(x, y));
        for (int i = 0; i < x; i++) {
            for(int j = 0; j < y; j++) {
                fields[i][j] = new Field();
                add(fields[i][j]);
            }
        }
        //...
    }

}

The size of the minefields are arbitrary, and are generated according the what difficulty the user chooses from the JMenuBar, with these methods:

    private void startBeginner() { startGame(8, 8, 10); }

    private void startIntermediate() { startGame(16, 16, 40); }

    private void startAdvanced() { startGame(16, 30, 99); }

    private void startGame(int x, int y, int m) {
        if(mineField != null) {
            remove(mineField);
        }

        mineField = new MineField(x, y, m);

        add(mineField, BorderLayout.CENTER);

        // ...
    }

Most of what I created for now seems to work, with one exception. That being when I want to start a new game of the same difficulty of my current one. What happens is that all the fields disappear form the window, which has a blank MineField (although I'm not sure, that might not even be there, too). How could I solve this issue?

Answer 1

This works for me:

When you want to remove the old board JPanel, and create a new one. First, remote it by calling the container panel (its parent)

parent.removeAll()

Now, addyour new board JPanel to parent JPanel like you did:

parent.add(mineField, BorderLayout.CENTER);

Then, by using the JFrame methods, refresh GUI by 2 methods one by one:

this.revalidate();
this.repaint();