判断是否及格保证程序不崩溃

package demo;
import javax.swing.JOptionPane;

class NotNumber extends Exception{
}
public class Credit {
    public static void main(String[] args){
        int cre = 0;
        String c;
        try{
        c=JOptionPane.showInputDialog("请输入成绩：");
        cre = Integer.parseInt(c);
        }
        catch(Exception e){    
            cre = 200;
        }
        if(cre<60)
        {
            JOptionPane.showMessageDialog(null,"不及格", "result",JOptionPane.INFORMATION_MESSAGE);
        }
        else if(cre<70){
            JOptionPane.showMessageDialog(null,"及格", "result",JOptionPane.INFORMATION_MESSAGE);
        }
        else if(cre<80){
            JOptionPane.showMessageDialog(null,"中", "result",JOptionPane.INFORMATION_MESSAGE);
        }
        else if(cre<90){
            JOptionPane.showMessageDialog(null,"良", "result",JOptionPane.INFORMATION_MESSAGE);
        }
        else if(cre<=100){
            JOptionPane.showMessageDialog(null,"优", "result",JOptionPane.INFORMATION_MESSAGE);
        }
        else if(cre==200){
            JOptionPane.showMessageDialog(null,"输入数据有误，请重新输入", "worning",JOptionPane.INFORMATION_MESSAGE);
        }
    }
    
}