About the inaccessibility of *\jre\lib\rt.jar

Look directly at the solution:

Right-click the object Project under Eclipse3.7 navigation -> select Properties -> select Java Build Path, find JRE System Library under the Library tab on the right side of the window 
-> Expand JRE System Library, find and double-click Access Rule, The Add Access Rule window appears, select "Allow access", and set rule/pattern: **.

After the above settings are completed, recompile.