When Eclipse compiles a Java class, there is no error in the program body, but there is an error message at the package

The error message is as follows:

The class file Hashmap<k,v>. Frontcache contains a signature .....

The solutions that are given online are:

"This problem arises because it is compiled under different JDK versions and can be resolved as follows:

Add JDK 1.7 under window-preferenecs-java-installed jres (if available);

Right-click Project-properties-java build Path-libraries-add LIBRARY-JRE System library point Next, choose Alternate JRE, choose JDK 1.7. "

However, prior to the general use of Eclipse, a JDK environment has been deployed, which is already encoded in jdk1.7,1.8, or even later, without the problem of JDK version compilation, which is logically nonexistent. Here is a very funny solution, is to delete the package line, re-write again just that line, Ctrl+s, and then found that the program is normal.

Of course, this kind of non-ambiguous error, it is estimated not to encounter one or two times, here as a way to share a different solution.

When Eclipse compiles a Java class, there is no error in the program body, but there is an error message at the package