Exception while compiling: wrong version 50.0, should be 49.0

Question

I am working an application with JXL API and when i tried compiling using eclipse IDE, it's working fine and the same is not compiling when i am trying to compile in Command prompt and showing the below exception..

Extract.java:6: cannot access jxl.read.biff.BiffException bad class file: C:\Program Files\Java\jdk1.5.0_01\jre\lib\ext\jxl.jar(jxl/read/biff/BiffException.class)
class file has wrong version 50.0, should be 49.0
Please remove or make sure it appears in the correct subdirectory of the classpa
th.
import jxl.read.biff.BiffException;
                     ^
1 error

EDIT:

I am able to executing using JDK 1.6. Since JDK 1.6 must also be compatible with lower versions, why doesn't it support the class files which were compiled in JDK 1.5.

Answer 1

The library you're using was compiled with Java 6

Your compiler is Java 5 that's why it doesn't understand that format.

To fix it you have to get a 1.5 version of the library or upgrade your compiler to 1.6 I suggest the later.

Answer 2

Per http://www.jnode.org/node/2140...

Submitted by Stephen Crawley on Fri, 11/30/2007 - 07:15.

I suspect that you are mixing code compiled with different versions of Java. Class file version 50.0 is used by Java 6.0, and 49.0 is used by Java 5.0.

Try doing a "build clean" to get rid of all existing class files, followed by a regular build.

JNode is being developed using Java 6.0 only. Last time I tried, it didn't build using Java 5.0 (aka 1.5). (It is a problem with the program that builds the JNode boot image.)

Try changing the builder in Eclipse. If you're using 3.4, it's Project - Properties - Java Compiler - Enable Project Specific Settings - Compiler Compliance Level = 1.6. You'll prolly also need to have JRE 1.6 installed, as well.

Answer 3

Check you class path in eclipse and make sure that its the same class path your compiling to in the command prompt, also check your library imports