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?

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.

you can configure VM in eclipse.ini file.