请问:package 和 NoClassDefFoundError

chaisave 2002-03-03 08:41:45
本行是C++,老是不会用java的package,能帮我瞧瞧吗?
是这样的:
// j:\java\test\Base.java
package java.test;
public class Base {
public Base() {system.out.print("base");}
}
// j:\java\test\Derived.java
package java.test;
public class Derived extends Base {
public Derived() {System.out.println("derived");}
}
系统的CLASSPATH = J:;//等等
结果,两个文件在j:\java下都可以编译:
J:\java> javac base.java
J:\java> javac derived.java
但是:
J:\java> java base 和java derived就会报NoClassDefFoundError的错
能告诉我应该怎么设置吗?Thanks.
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chaisave 2002-03-03
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thanks a lot,
i got an answer through newsgroup
c:> java java.test.Derived
derived
chaisave 2002-03-03
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谢谢楼上两位的帮助,命名模板?namespace吧,呵呵。
上面的例子中,忘记加一个main了!
package java.test;
public class Derived extends Base {
public Derived() {System.out.println("derived");}
public static void main(String[] args) {
Derived d = new Derived();
}
}
我在cmd窗口:
C:\echo %classpath%
.;E:\j2sdk1.4.0\jre\lib\rt.jar;J:
还是有错……
我把java Derived的提示再提一下:
Exception in thread "main" java.lang.NoClassDefFoundError: derived (wrong name:exam/derived)
我想并不是找不到class文件,而是名称不对。


peacock_king 2002-03-03
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又是classpath中少了“.;”
remote_roamer 2002-03-03
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你把package理解成c++的命名模板就差不多了.不过实际还是有一些差别
bread213 2002-03-03
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Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorld
方法就将classpath设为:classpath=.;c:\jdk1.2\lib\dt.jar;c:\jdk1.2\lib\tools.jar
java -classpath base
android 使用poi读取高版本excel, 解决以下这两个错误 java.lang.NoClassDefFoundError: Failed resolution of: Ljavax/xml/stream/XMLEventFactory; at org.apache.poi.openxml4j.opc.internal.marshallers.PackagePropertiesMarshaller.(PackagePropertiesMarshaller.java:41) at org.apache.poi.openxml4j.opc.OPCPackage.init(OPCPackage.java:161) at org.apache.poi.openxml4j.opc.OPCPackage.(OPCPackage.java:141) at org.apache.poi.openxml4j.opc.ZipPackage.(ZipPackage.java:97) at org.apache.poi.openxml4j.opc.OPCPackage.open(OPCPackage.java:324) at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:184) at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:149) javax.xml.stream.FactoryConfigurationError: Provider com.sun.xml.internal.stream.events.XMLEventFactoryImpl not found at javax.xml.stream.FactoryFinder.newInstance(Unknown Source) at javax.xml.stream.FactoryFinder.newInstance(Unknown Source) at javax.xml.stream.FactoryFinder.find(Unknown Source) at javax.xml.stream.FactoryFinder.find(Unknown Source) at javax.xml.stream.XMLEventFactory.newInstance(Unknown Source) at org.apache.poi.openxml4j.opc.internal.marshallers.PackagePropertiesMarshaller.(PackagePropertiesMarshaller.java:41) at org.apache.poi.openxml4j.opc.OPCPackage.init(OPCPackage.java:161) at org.apache.poi.openxml4j.opc.OPCPackage.(OPCPackage.java:141) at org.apache.poi.openxml4j.opc.ZipPackage.(ZipPackage.java:97) at org.apache.poi.openxml4j.opc.OPCPackage.open(OPCPackage.java:324) at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:184) at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:149)

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