Is Java really platform-independant?

03-12-2012

Moderator

6,876, 694

Join Date: Sep 2005

Last Activity: 10 February 2021, 3:50 AM EST

Location: Switzerland - GE

Posts: 6,876

Thanks Given: 594

Thanked 694 Times in 627 Posts

I missed your post Radoulov... sorry repeating things... and Thanks!

vbe

View Public Profile for vbe

Find all posts by vbe

03-12-2012

Registered User

5,690, 630

Join Date: Jan 2007

Last Activity: 9 January 2017, 4:40 AM EST

Location: Варна, България / Milano, Italia

Posts: 5,690

Thanks Given: 184

Thanked 630 Times in 587 Posts

Yes,
sure - the JVM itself *IS* platform specific.

radoulov

View Public Profile for radoulov

Find all posts by radoulov

03-12-2012

Registered User

117, 3

Join Date: Aug 2011

Last Activity: 26 November 2017, 12:41 AM EST

Posts: 117

Thanks Given: 31

Thanked 3 Times in 3 Posts

Code:

 
I believe the error you're seeing is related to JDK version mismatch.

Thanks radoulov buddy! You are absolutely right, there was a mismatch in JDK version. Java is really platform-independant, I think I've confirmed it. Thanks for your help.
Problem solved!

gabam

View Public Profile for gabam

Find all posts by gabam

03-12-2012

Registered User

2,288, 480

Join Date: Apr 2007

Last Activity: 3 May 2020, 8:28 AM EDT

Location: Saint Paul, MN USA / BSD, CentOS, Debian, OS X, Solaris

Posts: 2,288

Thanks Given: 430

Thanked 480 Times in 395 Posts

Hi.

Googling java Unsupported major.minor version produces essentially the answer provided by radoulov. The second of about 86K hits contained:

Quote:

It means that you compiled your classes under a specific JDK, but then try to run them under older version of JDK. So, you can't run classes compiled with JDK 6.0 under JDK 5.0. The same with classes compiled under JDK 7.0 when you try to run them under JDK 6.0.

-- Unsupported major.minor version 51.0 | Java.net

Google is your friend.

Best wishes ... cheers, drl

---------- Post updated at 11:18 ---------- Previous update was at 09:51 ----------

Hi.

Here is a script that compiles a java code on a 64-bit box with Sun java:

Code:

#!/usr/bin/env bash

# @(#) s1	Demonstrate translation of java code.

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
edges() { local _f _n _l;: ${1?"edges: need file"}; _f=$1;_l=$(wc -l $_f);
  head -${_n:=3} $_f ; pe "--- ( $_l: lines total )" ; tail -$_n $_f ; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C java

FILE=${1-hello.java}

pl " Input data file $FILE:"
cat $FILE

pl " Results, compile and execute:"
javac $FILE
ls -lgG hello*
java -verbose hello |
specimen 3

exit 0

producing:

Code:

% ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0.8 (lenny) 
bash GNU bash 3.2.39
java version "1.6.0_22"

-----
 Input data file hello.java:
public class hello
{
  public static void main( String[] args )
  {
    System.out.println( "Hello, world from java." );
  }
}

-----
 Results, compile and execute:
-rw-r--r-- 1 427 Mar 12 11:03 hello.class
-rw-r--r-- 1 127 Mar 12 10:34 hello.java
Edges: 3:0:3 of 308 lines in file "-"
[Opened /usr/lib/jvm/java-6-sun-1.6.0.22/jre/lib/rt.jar]
[Loaded java.lang.Object from /usr/lib/jvm/java-6-sun-1.6.0.22/jre/lib/rt.jar]
[Loaded java.io.Serializable from /usr/lib/jvm/java-6-sun-1.6.0.22/jre/lib/rt.jar]
   ---
Hello, world from java.
[Loaded java.lang.Shutdown from /usr/lib/jvm/java-6-sun-1.6.0.22/jre/lib/rt.jar]
[Loaded java.lang.Shutdown$Lock from /usr/lib/jvm/java-6-sun-1.6.0.22/jre/lib/rt.jar]

Now the code will be transferred to a 32-bit box running GNU java, and only executed with this script:

Code:

#!/usr/bin/env bash

# @(#) s1	Demonstrate execution of 64-compiled java on 32-bit platform.

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
edges() { local _f _n _l;: ${1?"edges: need file"}; _f=$1;_l=$(wc -l $_f);
  head -${_n:=3} $_f ; pe "--- ( $_l: lines total )" ; tail -$_n $_f ; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C java

FILE=${1-hello.class}

pl " Input data file $FILE:"
file $FILE

pl " Results, execute:"
ls -lgG hello*
pe
java -verbose hello 2>&1 |
specimen 3

exit 0

producing:

Code:

./s1

Environment: LC_ALL = C, LANG = en_US.UTF-8
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-686, i686
Distribution        : Debian GNU/Linux 5.0 
GNU bash 3.2.39
java version "1.5.0" ( gij (GNU libgcj) version 4.3.2 )

-----
 Input data file hello.class:
hello.class: data

-----
 Results, execute:
-rw-r--r-- 1 427 Mar 12 11:03 hello.class
-rw-r--r-- 1 127 Sep 17  2009 hello.java
-rw-r----- 1 108 Jan  6  2008 hello.java.orig

Edges: 3:0:3 of 256 lines in file "-"
[Loaded (pre-compiled) java.lang.ClassLoader from <no code source>]
[Loaded (pre-compiled) java.lang.Object from <no code source>]
[Loaded (pre-compiled) java.lang.Class from <no code source>]
   ---
[Loaded (pre-compiled) java.util.Vector$1 from <no code source>]
[Loaded (bytecode) hello from (file:/home/drl/try/java/hello/ <no certificates>)]
Hello, world from java.

My conclusion is that for simple codes, java is platform independent. Whether or not this holds for complex codes is left as an exercise.

Best wishes ... cheers, drl

drl

View Public Profile for drl

Find all posts by drl

Programming

Is Java really platform-independant?