[java] The type java.lang.CharSequence cannot be resolved in package declaration

I get 2 classes in package P. Interface class A and its implementation class B. In the file with class B I get the following error: The type java.lang.CharSequence cannot be resolved. It is indirectly referenced from required .class files.

I'm using Eclipse Helios and

$ java -version
java version "1.8.0_05"
Java(TM) SE Runtime Environment (build 1.8.0_05-b13)
Java HotSpot(TM) Server VM (build 25.5-b02, mixed mode)

Standard solution of removing and adding JRE doesn't work. How can I fix it?

EDIT: Code:
Class A:

package com.jax;

import javax.jws.WebMethod;
import javax.jws.WebService;
import javax.jws.soap.SOAPBinding;
import javax.jws.soap.SOAPBinding.Style;


@WebService
@SOAPBinding(style = Style.RPC)
public interface WebServiceInter {

@WebMethod
String sayHello();

}

Class B:

package com.jax; // **Error is here**

import javax.jws.WebService;

@WebService(endpointInterface = "com.jax.WebServiceInter")
public class WebServiceImpl implements WebServiceInter{
    @Override
    public String sayHello(){
        return "Hello!";
    }
}

Project structure: ProjectName -> Java Resources -> com.jax -> Class A, Class B

Make your Project and Workspace to point to JDK7 which will resolve the issue. https://developers.google.com/eclipse/docs/jdk_compliance has given ways to modify Compliance and Facet level changes.

Just trying to compile with ant, Have same error when using org.eclipse.jdt.core-3.5.2.v_981_R35x.jar, Everything is well after upgrade to org.eclipse.jdt.core_3.10.2.v20150120-1634.jar

"Java 8 support for Eclipse Kepler SR2", and the new "JavaSE-1.8" execution environment showed up automatically.

Download this one:- Eclipse kepler SR2

and then follow this link:- Eclipse_Java_8_Support_For_Kepler

Your Eclipse software suite doesn't support Java 1.8

Download a newer version of Eclipse.