I am using Java EE 6.0, the highest version supported by myEclipse 10, to develop a web app. The project's "compiler compliance level" is confined less than or equal to 1.6, otherwise, myEclipse will give me a warning. My JDK is 1.8.0_91.
What the trouble is, althought the environment settings looks like correct and the grammer of my app is right, there is still a fatal problem like this:
"The type java.lang.CharSequence cannot be resolved. It is indirectly referenced from required .class files".
With the helps of internet, I guess that the reason of this trouble may be version mismatch between JDK and Java EE SDK, or something else mismatch. But what is the real reason on earth and how should I correct the problem?