帮忙看看都有哪些错误

[kangwor]

import javax.swing.JOptionPane;
public class testone
{
public static void main(String [] args)
{
int total,gradCounter,gradeValue,average;
String grade;
total=0;
gradeCounter=1;
while(gradeCounter<=10)
{
gradeJOptionPane.showInputDialog("Enter");
gradevalue=Integer.parseInt(grade);
total=total+gradeValue;
gradeCounter=gradeCounter+1;

}
average=total/10;
JOptionPane.showMessageDialog(null,"class average is",JOptionPane.INFORMATION_MESSAGE);
System.exit(0);
}
}

[kangwor]

老师给的程序

[老廉颇尚能饭否]

import javax.swing.JOptionPane;

public class testone {
	public static void main(String[] args) {
		int total, gradeCounter, gradeValue, average;
		String grade;
		total = 0;
		gradeCounter = 1;
		while (gradeCounter <= 10) {
			try {
				grade = JOptionPane.showInputDialog("Enter");
				gradeValue = Integer.parseInt(grade);
				total = total + gradeValue;
				gradeCounter = gradeCounter + 1;
			} catch (Exception e) {
			}
		}
		average = total / 10;
		JOptionPane.showMessageDialog(null, "average is" + average,
				"class average", JOptionPane.INFORMATION_MESSAGE);
		System.exit(0);
	}
}

[kangwor]

为什么我们老师给的程序就编译成功了呢？