Solution to not compiling class files in eclipse

From: http://blog.csdn.net/xuanze520/archive/2008/02/05/2084280.aspx

The solution to this problem is summarized as follows:

1. Check whether project --> build automatically is selected? If not, clean it and restart eclipse.

2. check whether there are unnecessary (redundant) jar packages in your Lib, and check whether there is any wrong path in your. classpath file.

3. This is the most important point. check whether there are any error messages about this project in the problems view. This is generally the case:
The project cannot be built until build path errors are resolved

The following message is displayed: unbound classpath. You can delete these paths in. classpath.