处理报错：java/lang/NoClassDefFoundError: java/lang/Object

处理报错：java/lang/NoClassDefFoundError: java/lang/Object

 

操作系统环境：CentOS6.0  2.6.32-220.el6.x86_64
JDK版本环境：jdk1.5.0_22

操作系统原来安装的是jdk1.6,后来开发人员要求java程序使用jdk1.5版本的。帮开发下载JDK1.5,
安装完JDK ，设定环境变量后出现这个错误：

[root@fztest97 lib]# javac
Error occurred during initialization of VM
java/lang/NoClassDefFoundError: java/lang/Object
[root@fztest97 lib]# java
Error occurred during initialization of VM
java/lang/NoClassDefFoundError: java/lang/Object

首先要确认的是环境变量的设置是否正确，其次，需要确认的就是lib和jre/lib文件夹中的rt和tools是否是打包后的形式，如果发现rt.pack 和 tools.pack 那么多半问题就出在这里。
解决方法也很简单，只要将相应文件解压成rt.jar 和 tools.jar，可以使用bin里面的unpack200工具，
如：unpack200 rt.pack rt.jar

 

/apps/usr/java/jdk1.5.0_22/lib/tools.pack  转为  tools.jar  
/apps/usr/java/jdk1.5.0_22/jre/lib/rt.pack   转为  rt.jar

 

执行如下操作命令：

 

[root@fztest97 ]# cd /apps/usr/java/jdk1.5.0_22/lib/
[root@fztest97 lib]# unpack200 tools.pack tools.jar
[root@fztest97 lib]# ls
dt.jar ir.idl jconsole.jar orb.idl sa-jdi.jar tools.jar tools.pack
[root@fztest97 lib]# cd /apps/usr/java/jdk1.5.0_22/jre/lib
[root@fztest97 lib]# unpack200 rt.pack rt.jar
[root@fztest97 lib]# ll rt.*
-rw-r--r--. 1 root root 40232487 May 23 19:23 rt.jar
-rw-r--r--. 1 root root 12960918 May 23 19:07 rt.pack

 
再次执行如下命令，进行验证：

[root@fztest97 lib]# java -version
java version "1.5.0_22"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_22-b03)
Java HotSpot(TM) 64-Bit Server VM (build 1.5.0_22-b03, mixed mode)

[root@fztest97 lib]# javac
Usage: javac <options> <source files>
where possible options include:
  -g Generate all debugging info
  -g:none Generate no debugging info
  -g:{lines,vars,source} Generate only some debugging info
  -nowarn Generate no warnings
  -verbose Output messages about what the compiler is doing
  -deprecation Output source locations where deprecated APIs are used
  -classpath <path> Specify where to find user class files
  -cp <path> Specify where to find user class files
  -sourcepath <path> Specify where to find input source files
  -bootclasspath <path> Override location of bootstrap class files
  -extdirs <dirs> Override location of installed extensions
  -endorseddirs <dirs> Override location of endorsed standards path
  -d <directory> Specify where to place generated class files
  -encoding <encoding> Specify character encoding used by source files
  -source <release> Provide source compatibility with specified release
  -target <release> Generate class files for specific VM version
  -version Version information
  -help Print a synopsis of standard options
  -X Print a synopsis of nonstandard options
  -J<flag> Pass <flag> directly to the runtime system

到此为止，JDK1.5安装配置成功。