Compiler Errors...it ran yesterday!?

Question

This is a pre-existing Java project being run in Eclipse 3.5.2 32 bit..

Day 1:
Install Java SE 6 Update 20 JDK.
Experience Crash in Eclipse.
Install Java 5.
Same problem-(uninstall java 5).
Re-install Java 6.
Install Eclipse 3.3.1.
Install Eclipse 3.5.2. 32-bit.
No problems.
Run Eclipse 3.5.2. 64-bit.
No problems.
Set up the project, configure, and run.
No problems.

Day 2:

Load Eclipse to start a new project.
Previous project now has 940 errors.
Error Type is "Java Problem".

The project ran 100% without a problem on Day 1. The only thing that happened between Day 1 and Day 2 was restarting my computer. I just tried to recreate the project, step by step, and am still getting the same errors.

I know it's not the code -- it was working. Not to mention that it's an opensource project, such a problem would be documented.

I'm thinking something is wrong with my Java install. Or, perhaps, it's a 32-bit/64-bit problem. I'm running win7 64bit.

So before formatting my Windows partition, I thought I'd throw the problem your way to see if anyone knows what's going on.

Thanks.

Answer 1

It would help if you included a couple of the errors you're getting, but most likely it's saying every standard library class doesn't exist, which means eclipse doesn't have the correct path to the JDK on your machine. I don't know why that would've happened post-restart, but I've seen it happen before after a Java reinstall

Open Preferences and under Java -> Installed JREs, check that the path is correct