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How to target JRE 1.5?

Posted on 2008-10-20
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Last Modified: 2012-08-13
Hi,

In eclipse, I see my java project is using JRE 1.6.

Unfortunately the mac I'm targeting is only at JRE 1.5, and it looks like that's not going to change.

Can I somehow download the old JRE on my system (without messing up the current one...) and have eclipse recompile the project using JRE 1.5? I'm on a windows machine.

Thanks
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Question by:DJ_AM_Juicebox
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5 Comments
 

Author Comment

by:DJ_AM_Juicebox
ID: 22764638
Actually i just downloaded a different JRE and see how to use it for compilation.

I'm using JRE 1.5.0_06 while the mac I'm targeting has 1.5.0_16-b06-284.

I don't get any useful error messages, just:

  java.lang.UnsupportedClassVersionError: Bad version number in .class file
      at java.lang.ClassLoader.defineClass1(Native Method)
      at java.lang.ClassLoader.defineClass(ClassLoader.java:675)
      at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
      at java.net.URLClassLoader.defineClass(URLClassLoader.java:260) at
      .....
     sun.applet.AppletPanel.run(AppletPanel.java:326)
     at java.lang.Thread.run(Thread.java:613)

what does that mean?
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LVL 6

Accepted Solution

by:
javaexperto earned 1000 total points
ID: 22764654
well it means that your .class file was compiled with other version of the JDK and you are trying to run with another JRE versión.
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Author Comment

by:DJ_AM_Juicebox
ID: 22766170
Hmm I don't understand - in eclipse I don't see anyplace to choose which JDK version to compile with - only to choose which JRE to target. So my JDK is fixed, but the JRE can be variable. What should I do?
0
 
LVL 17

Assisted Solution

by:aiklamha
aiklamha earned 1000 total points
ID: 22766268
To compile you need a compatible JDK...

In my version of eclipse... (i.e. 3.1) i would right click on my project, go to properties and i will select Java Compiler from the left pane... it will show me which JDK my project should be compile-compatible with.. i have JDK 1.3, 1.4 and 5 installed .... it will list all of them in a combo... I selected the one i wanted...
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Author Comment

by:DJ_AM_Juicebox
ID: 22766359
Ok, well that fixed it, I picked a 5.0 compatible JDK.

However the applet just exits with no error recorded in the log files. So much for cross platform compatibility!

Thanks
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