多态与异常处理课后作业

import javax.swing.*;

public class Test {
    public static void input()
    {
        while(true)
        {
            double i=0;
            String s=JOptionPane.showInputDialog("输入分数：");
            try
            {
                i=Double.parseDouble(s);
            }
            catch(NumberFormatException e)
            {
                JOptionPane.showMessageDialog(null,"输入错误","验证结果：",JOptionPane.PLAIN_MESSAGE );
                input();
            }
            finally
            {
                JOptionPane.showMessageDialog(null,"OK","验证结果：",JOptionPane.PLAIN_MESSAGE );
            }
            if(0<=i&&i<60)
            {
                JOptionPane.showMessageDialog(null,"不及格","验证结果：",JOptionPane.PLAIN_MESSAGE );
                System.exit(0);
            }
            else if(i>=60&&i<70)
            {
                JOptionPane.showMessageDialog(null,"及格","验证结果：",JOptionPane.PLAIN_MESSAGE );
                System.exit(0);
            }
            else if(i>=70&&i<80)
            {
                JOptionPane.showMessageDialog(null,"良好","验证结果：",JOptionPane.PLAIN_MESSAGE );
                System.exit(0);
            }
            else if(i>=80&&i<=100)
            {
                JOptionPane.showMessageDialog(null,"优秀","验证结果：",JOptionPane.PLAIN_MESSAGE );
                System.exit(0);
            }
            else
            {
                JOptionPane.showMessageDialog(null,"超出范围","验证结果：",JOptionPane.PLAIN_MESSAGE );
            }
        }
    }
    public static void main(String[] args){
        input();
    }
}