java小程序之(GUI)确认对话框JOptionPane.showConfirmDialog

猜生日，示例程序：

//import javax.swing.JOptionPane;
import javax.swing.*;
public class Demo032401{
    public static void main( String [] args ){
        String s1 = 
                            " 1 3 5 7\n " + 
                            " 9 11 13 15 \n " +
                            " 17 19 21 23\n " +
                            " 25 27 29 31\n ";
        String s2 = 
                            " 2 3 6 7\n " +
                            " 10 11 14 15\n " +
                            " 18 19 22 23\n " +
                            " 26 27 30 31\n ";
        String s3 = 
                            "4 5 6 7\n " +
                            " 12 13 14 15\n " +
                            " 20 21 22 23\n " +
                            " 28 29 30 31\n ";
        String s4 = 
                            " 8 9 10 11\n " +
                            " 12 13 14 15\n " +
                            " 24 25 26 27\n " +
                            " 28 29 30 31\n ";
        String s5 =
                            " 16 17 18 19\n " +
                            " 20 21 22 23\n " +
                            " 24 25 26 27\n " +
                            " 28 29 30 31\n ";
        int day = 0;
        int answer = JOptionPane.showConfirmDialog( null, " Is your birthday in these numbers?\n " + s1 );
        if ( answer == JOptionPane.YES_OPTION )
            day += 1;

        answer = JOptionPane.showConfirmDialog( null, " Is your birthday in these numbers?\n " + s2 );
        if ( answer == JOptionPane.YES_OPTION )
            day += 2;

        answer = JOptionPane.showConfirmDialog( null, " Is your birthday in these numbers?\n " + s3 );
        if ( answer == JOptionPane.YES_OPTION )
            day += 4;

        answer = JOptionPane.showConfirmDialog( null, " Is your birthday in these numbers?\n " + s4 );
        if ( answer == JOptionPane.YES_OPTION )
            day += 8;

        answer = JOptionPane.showConfirmDialog( null, " Is your birthday in these numbers?\n " + s5 );
        if ( answer == JOptionPane.YES_OPTION )
            day += 16;

        //show your birthday number
        JOptionPane.showMessageDialog( null, " Your birthday number is " + day + " ! " );
        System.out.println( "RUN OVER!!!" );
    }
}