程序代码：

　package zs1;

import javax.swing.JOptionPane;

public class zs12 
{
  public static void main(String args[])
    {
     int month= 4;
     String season;
     if(month == 12 ||month == 1 ||month == 2);
          {season = "冬天";}
     else if(month == 3||month == 4||month == 5);
         {season = "春天";}
     else if(month == 6|| month== 7||month == 8);
         {season = "夏天";}
     else if(month == 9||month == 10||month == 10);
         {season = "秋天";}
     else
         {season = "不合法的月份";}
     JOptionPane.showMessageDialog(null,"四月是" + season +".");
     System.exit(0);
    } 
}