How do i configure eclipse to make use of different version of JDK

I have 开发者_运维技巧three project running on eclipse i want to use JDK 1.4 for two project and JDK 1.6 for third project how do i do that?

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You need:

• first to declare the different JRE in your Eclipse: See "Eclipse - no Java (JRE) / (JDK) … no virtual machine…"
• then to add the right JRE in your project settings (see this blog post for instance)

The default JRE is shown with a check mark and is used by new eclipse projects unless the project specifically overrides the value.
So the next step is to check which JRE the current project is using.

• Right click the project and choose "properties".
• Select "Java Build Path" and then click the tab labeled "Libraries". You should see an entry like "JRE System Library [version]".
  To change the JRE version,
  • highlight the entry and click "Remove".
  • Then click "Add Library...". Choose "JRE System Library".
    If you choose "Workspace Default", the project will use the JRe defined under "Windows -> Properties" as explained above.
    You may also specify an alternate JRE located somewhere on your file system, or choose an embedded execution environment provided by Eclipse.

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you can configure VM in eclipse.ini file.