error in running java

Mridulj · 04-15-2009, 01:22 AM

I have installed jdk 1.6 .when I compile file (java)
it compiles creating a class file but when I use the
java command it gives errors .

$javac ArraySortSearch.java (compiles successfully : no errors)

$java ArraySortSearch

Exception in thread "main" java.lang.NoClassDefFoundError: while resolving class: ArraySortSearch
at java.lang.VMClassLoader.resolveClass(java.lang.Class) (/usr/lib/libgcj.so.5.0.0)
at java.lang.Class.initializeClass() (/usr/lib/libgcj.so.5.0.0)
at java.lang.Class.forName(java.lang.String, boolean, java.lang.ClassLoader) (/usr/lib/libgcj.so.5.0.0)
at java.lang.Class.forName(java.lang.String) (/usr/lib/libgcj.so.5.0.0)
at gnu.gcj.runtime.FirstThread.run() (/usr/lib/libgcj.so.5.0.0)
at _Jv_ThreadRun(java.lang.Thread) (/usr/lib/libgcj.so.5.0.0)
at _Jv_RunMain(java.lang.Class, byte const, int, byte const, boolean) (/usr/lib/libgcj.so.5.0.0)
at __gcj_personality_v0 (/root/Desktop/java.version=1.4.2)
at __libc_start_main (/lib/tls/libc-2.3.4.so)
at _Jv_RegisterClasses (/root/Desktop/java.version=1.4.2)
Caused by: java.lang.ClassNotFoundException: java.lang.StringBuilder not found in [file:/usr/share/java/libgcj-3.4.6.jar, file:./, core:/]
at java.net.URLClassLoader.findClass(java.lang.String) (/usr/lib/libgcj.so.5.0.0)
at gnu.gcj.runtime.VMClassLoader.findClass(java.lang.String) (/usr/lib/libgcj.so.5.0.0)
at java.lang.ClassLoader.loadClass(java.lang.String, boolean) (/usr/lib/libgcj.so.5.0.0)
at _Jv_FindClass(_Jv_Utf8Const, java.lang.ClassLoader) (/usr/lib/libgcj.so.5.0.0)
at java.lang.Class.forName(java.lang.String, boolean, java.lang.ClassLoader) (/usr/lib/libgcj.so.5.0.0)
at _Jv_BytecodeVerifier.verify_instructions_0() (/usr/lib/libgcj.so.5.0.0)
at _Jv_VerifyMethod(_Jv_InterpMethod) (/usr/lib/libgcj.so.5.0.0)
at _Jv_PrepareClass(java.lang.Class) (/usr/lib/libgcj.so.5.0.0)
at _Jv_WaitForState(java.lang.Class, int) (/usr/lib/libgcj.so.5.0.0)
at java.lang.VMClassLoader.linkClass0(java.lang.Class) (/usr/lib/libgcj.so.5.0.0)
at java.lang.VMClassLoader.resolveClass(java.lang.Class) (/usr/lib/libgcj.so.5.0.0)
...9 more

jay73 · 04-15-2009, 01:35 AM

That message indicates you are not running jdk but gcj. The latter contains only a selection of the classes that were introduced in java 1.5 so it often causes compilation errors if code contains references to any of those newer classes.

Mridulj · 04-15-2009, 08:57 AM

I am using JDK since I have compiled using javac and afterthat
used java command.

jay73 · 04-15-2009, 12:33 PM

No, you are not. GCJ uses the java and javac commands, too, so that does not say much. Look at the details of the error messages instead to find out; it's "gcj" all over.

Mridulj · 04-15-2009, 01:17 PM

then how do i use the jdk to compile my java programs and
then run them .

Robhogg · 04-15-2009, 01:26 PM

Which distro are you using? If it's Debian or one of it's offspring, then you could use update-alternatives:

Code:

update-alternatives --config javac

So long as the JDK is installed somewhere where the alternatives system can find it, you can select it from a menu. If not, you will probably find that javac is a symbolic link to the actual program - just modify the link to point to the version from the JDK.

Mridulj · 04-15-2009, 01:35 PM

I am using RHEL4 .

how do I modify the link to point to the version from the JDK so
that I can use javac and java

Robhogg · 04-15-2009, 03:00 PM

You could do it like this:

Code:

$ which javac #find out where it is
/usr/bin/javac
$ file java # check that it really is a link
/usr/bin/javac: symbolic link to '/path/to/gcj/javac'
$ rm /usr/bin/javac # remove the link
$ ln -s /path/to/jdk/javac /usr/bin/javac # recreate it

The last two steps would need to be done as root (or using sudo). If file tells you that javac is actually the executable file, rather than a link, you should either remove gcj using yum, rather than rm'ing javac:

Code:

yum remove gcj # I believe, not so used to yum yet

... to avoid causing problems with the package management system, or create a symbolic link to javac in a directory that appears in the $PATH environment variable before /usr/bin (or wherever javac is located). For instance,

Code:

rob:~$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/home/rob/scripts

... shows me that /usr/local/bin appears before /usr/bin, so I could make a link to javac there, and it would take precedence over the link in /usr/bin:

Code:

$ ln -s /path/to/jdk/javac /usr/local/bin/javac

You'll probably want to do likewise for java as well (and definitely if you remove gcj).

jay73 · 04-15-2009, 05:54 PM

Well, you can always install openJDK from the fedora repositories. It is an open source implementation of the Sun JDK and it is available in RPM format.

Frankly, RHEL is about the worst choice you can make if you need to run the Sun JDK. To my knowledge, it is one the few distros that has made a point of refusing to include that type of software. Sure, it can be made to work but why bother - and although good as a basic solution, Robhogg's solution does not explain how to get the other thirty or so JDK executables to work or how to switch from one JDK to another one. And removing gcj is only feasible if you do not install Eclipse; if I remember well, it is one of its dependencies.

Mridulj · 04-16-2009, 12:13 PM

is it possible to install openJDK from the fedora repositories
in RHEL 4 .

jay73 · 04-16-2009, 03:56 PM

I don't use RHEL so I can't tell. I believe that Red Hat has its own repositories for subscribers. In addition, there are a number of third party repositories, for example:
http://jpackage.org/
If you follow their instructions, you can install the Sun JDK. Jpackage has many java related package but - for licensing reasons - they require you to get the JDK directly from Sun, then you can use one of their packages to make installing it easier.
Then there is also
http://dag.wieers.com/rpm/packages.php
Many other packages there but it appears that the openJDK is not included.