执行了javac出现以下错误：
C:\Documents and Settings\Administrator>javac -d path "c:\program files\adventne
t\webnms\examples\map_filters\LabelUpdateFilter.java"


c:\program files\adventnet\webnms\examples\map_filters\LabelUpdateFilter.java:16
: package com.adventnet.nms.topodb does not exist
import com.adventnet.nms.topodb.*;


c:\program files\adventnet\webnms\examples\map_filters\LabelUpdateFilter.java:23
: cannot resolve symbol
symbol : class ExtendedMapFilter
location: class test.LabelUpdateFilter
public class LabelUpdateFilter implements ExtendedMapFilter

为什么是这两种错误？

请大家指点一下。