哪位大神看看哪里错了
public class D{
public static void main(String[] args){
int num = 999;
int count = 0;
if (num >= 0 && num <=999999999);
while (num != 0){
count++;
num /= 10;
}
System.out.println("它是一个"+count+"位数!");
else{
System.out.println("输入有误");
}
}
}