[eclipse] Access restriction on class due to restriction on required library rt.jar

  . 問題 : [eclipse]換workspace時發生
            =>Access restriction on class due to 
              restriction on required library rt.jar 
  
  . 解法 : 方法1
            1. Go to the Build Path settings in the project properties. 
            2 Remove the JRE System Library 
            3 Add it back; Select "Add Library" and select the JRE System Library. 

           方法2 
            window - > java -> compiler -> error/warning -> deprecated and restricted api 把 forbidden reference 將 error change to warning