how to show JOptionPane on the top of all windows

Question

I have created a DialogUtil which shows numbers of JOptionPan in different situation. sometimes in my action class call to this method with null parameters as below.

Answer 1

public static void showNotExist(JPanel panel, String action) {
    JOptionPane.showMessageDialog(rootPane, new JLabel(action.concat(" doesn't exist."), 2));
}

Try giving the rootpane as the 1st value in the showMessageDialog section