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I was wondering if there would be any implications (slowed performance, crashes and so on), running a java 1.4 application and a java 1.6 application on the same machine

Kara
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David
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    maybe this can help you [different versions of jre under win][1] [1]: http://stackoverflow.com/questions/271609/multiple-java-versions-running-concurrently-under-windows – DRastislav Dec 24 '12 at 11:32
  • thanks for the link, i couldn't find it myself. – David Dec 25 '12 at 05:59

5 Answers5

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Different java version are installed in different directories so running 2 java programs with different JRE version will not make any effect other than that you are running 2 processes of java.

So bottom line, there is no problem with that, it will not slow you down.

Also, java 6 has better performance than 1.4 so if you can run both on 6 its usually better.

Aviram Segal
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None, The only problem is you can only have one default JVM. If you have too many versions e.g. hundreds it is likely to be a bit of mess, but it won't slow you down.

Peter Lawrey
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It seems that the header does not correspond the question. Running different jre versions on the same machine is not the same as running a java 1.4 application and a java 1.6 application. So I will give 2 answers

  1. Yes you can have 2 different jre installed on your machine.

  2. You can run 1.4 application (classes compiled in Javac 1.4) on JRJ 1.6 but you cannot run 1.6 application (classes compiled in Javac 1.6) on JRE 1.4.

Evgeniy Dorofeev
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Of course, It will not slow machine. A machine can have multiple JVM on single machine. There will not be any kind of conflict because everything would be in separate folder.

There is only special case in case of multiple JDK/JRE.

Case : - What version will be used by your browser.

For this you can control all the things from java console from control panel in windows.

S.P Singh
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Yes, you can have multiple JRE installed on the same machine on the same O/S. And you can have one project configured with one version of Java Compiler on your IDE. But remember when you run Higher version of Java compiled code on a JRE having lower version, you might face some issues with the new features and enhancements introduced with the later versions.

ramesh
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