Animation doesn't show when used as action?

I have this little input animation, basically just a pause between value changes, it shows nicely when I just place it in the main arguments.

But when I try attaching it to a button, the program just freezes for the amount of time it takes to "input" and then it just shows the final product.

Can I fix this? Do you guys need some example code?

Code:

---

        public void solve(){
                for (int a = 0; a < 9; a++){
                        for (int b = 0; b < 9; b++){
                            try {
                                        Thread.sleep(10);
                                } catch (InterruptedException e) {
                                        // TODO Auto-generated catch block
                                        e.printStackTrace();
                                }
                                Grid[a][b].setText(String.valueOf(answer[a][b]));
                        }
                }
        }

---

it just replaces button names, it works when I simply call the method, but when it's in:

Code:

---

final JMenuItem solve = new JMenuItem("Solve");
            solve.addActionListener(new ActionListener(){
                    public void actionPerformed(ActionEvent e){
                            solve();
                            JOptionPane.showMessageDialog(null, "WIN!!...wait...");
                    }
            });

---

When I have sleep set as 10, it waits a bit, then shows everything, set as 100, then waits 10 times as long.

can anyone help?

Because code invoked from a "listener" executes on the GUI Event Dispatch Thread (EDT). Since you tell this thread to sleep the GUI can't repaint itself until all the code is finished executing. You need to start a separate Thread, so that thread sleeps and not the EDT.

Read the section from the Swing tutorial on "Concurrency" for more information.