Unable to use old java projects in new eclipse installation

I did an upgrade of my windows OS and restored my eclipse workspace from my backup. Now, when I try to open any of the older projects, they complain with a message:

Unbound classpath container: 'JRE System Library [jre6]' i开发者_运维问答n project <ProjectName>

When I looked around, I found pages which suggest that I change the JRE version for the project. However, I have about 50 projects in this workspace and do not want to change the value for each of them.

Any suggestions would be welcome.

Thanks and regards,

Karthick S.

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You should add a new JRE and name it [jre6] (or rename your current JRE). That will prevent you from changing manually your 50 projects. Window -> Preferences -> Java -> Installed JREs -> Add...

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The problem is that if you backed up the eclipse project files, then these contain information regarding paths to your JRE or JDK install and any external jars (specific to your last install). There are 2 files that you can edit with any text editor to fix this problem .classpath and .project.

Other option would be to delete the classpath and project files and try to import the project as java project using File > Import.