处理报错：java/lang/NoClassDefFoundError: java/lang/Object
操作系统环境：CentOS6.0 2.6.32-220.el6.x86_64JDK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]# javacError occurred during initialization of VMjava/lang/NoClassDefFoundError: java/lang/Object[root@fztest97 lib]# javaError occurred during initialization of VMjava/lang/NoClassDefFoundError: java/lang/Object
首先要确认的是环境变量的设置是否正确，虚拟主机，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，免备案空间，可以使用bin里面的unpack200工具，香港服务器，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]# lsdt.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.jar1 root root 40232487 May 23 19:23 rt.jar1 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 -versionjava 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]# javacUsage: 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 pathSpecify where to place generated class files-encoding <encoding> Specify character encoding used by source filesProvide source compatibility with specified releaseGenerate class files for specific VM version-version Version informationa 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。
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