Throw java为什么提示错误

Question

public class Defind {
public static void main(String[] args) {
try
{
throw new DefindException("异常");
}
catch(DefindException e)
{
System.out.println(e);
}
}

class DefindException extends Exception
{
public DefindException(String msg)
{
super(msg);
}
}
}