System.out.println("i -->"+i); This statement give runtime error on linux

[minal silimkar]

I tried following code on redhat 4, java 6 is installed on my machine.

    
[root@OracleVM java]# cat -n Hello.java
     1  class Hello
     2  {
     3          public static void main(String[] args){
     4                  int i=10;
     5                  System.out.println("i -->"+i);
     6          }
     7  }
[root@OracleVM java]# javac Hello.java
[root@OracleVM java]# java Hello
Exception in thread "main" java.lang.NoClassDefFoundError: while resolving class: Hello
   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/java/java.version=1.4.2)
   at __libc_start_main (/lib/tls/libc-2.3.4.so)
   at _Jv_RegisterClasses (/root/java/java.version=1.4.2)
Caused by: java.lang.ClassNotFoundException: java.lang.StringBuilder not found in [file:/usr/share/java/libgcj-3.4.3.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

If I write

    
System.out.println("i -->");
or
System.out.println(i);

Code wroks, but if I write

    
System.out.println("i -->"+i);

It gives error as shown above.

[Rob Spoor]

Originally posted by minal silimkar:
Caused by: java.lang.ClassNotFoundException: java.lang.StringBuilder not found in [file:/usr/share/java/libgcj-3.4.3.jar, file:./, core:/]

For Java 5.0 and up, the compiler turns string concatenation using + into a StringBuilder call:

"i -->"+i

is equal to

new StringBuilder().append("i -->").append(i).toString()

Now it seems that you are using the JVM that was shippedd with GCJ for executing. That one seems to miss all the Java 5.0 and up features, but more importantly its classes.

Try compiling with -source 1.4 -target 1.4 and see if it works then. This should remove the references to StringBuilder.

Or you could try upgrading your GCJ first and see if the latest version includes StringBuilder.

[minal silimkar]

Originally posted by Rob Prime

Try compiling with -source 1.4 -target 1.4 and see if it works then. This should remove the references to StringBuilder.
Or you could try upgrading your GCJ first and see if the latest version includes StringBuilder.

I tried compiling same code with -source 1.4 -target 1.4, it works.
I don't have any idea about GCJ, so I didn't tried. Please elaborate GCJ.

[Janardan Kelkar]

shouldn't the class be public?

[Rob Spoor]

Originally posted by minal silimkar:
I don't have any idea about GCJ, so I didn't tried. Please elaborate GCJ.

GCJ is part of GCC (Gnu Compiler Collection), and can compile Java source code to native code (mostly Linux only). Unfortunately, it has never had complete support for all classes in the API.

Your stack trace mentioned libgcj so that was why I expected that you were using it.

Originally posted by Janardan Kelkar:
shouldn't the class be public?

No it shouldn't. Default (package level) access is also allowed.

[minal silimkar]

I installed netbeans6.5 and tried

System.out.println("i -->"+i);

It is working fine.
But on terminal this statement gives error.

[Jesper de Jong]

Make sure you are using Sun Java instead of GCJ. You're using GCJ instead of Sun Java 6, despite Java 6 being installed on your machine. How you can make sure that you're using Java 6 instead of GCJ is something that you could best ask on a forum about Red Hat Linux.

What do you get if you give the following command in a terminal?

java -version

[ December 30, 2008: Message edited by: Jesper Young ]

[Campbell Ritchie]

You would probably use Sun Java instead of GCJ by installing Java in the usual fashion then setting your PATH to have the Sun version appear first.

If you install in /usr/java/jdk1.6... you can add this line to the .bashrc file in your ~ directory

export PATH=/usr/java/jdk1.6.0_11/bin/:$PATH

Obviously you can install Java in a different directory.