Access restriction: The type * is not accessible due to restrict，报错问题

报错信息:Access restriction: The type **  is not accessible due to restriction on required library

解决方案1： 

Eclipse 默认把这些受访问限制的API设成了ERROR。 
Windows -> Preferences -> Java -> Compiler -> Errors/Warnings -> 
Deprecated and trstricted API -> Forbidden reference (access rules): -> change to warning 

解决方案2： 
只需要在project build path中先移除JRE System Library，再添加库JRE System Library，重新编译后就一切正常了。 

解决方案3： 

工程上右键->工程属性->java builder path->Libraries标签，点击JRE System Library里面的Access rules，add sun/** 为accessible，如果该项存在，就edit。 

解决方案4： 

Windows -> Preferences -> Java -> Installed JREs -> 选择用的JDK -> Edit -> Add External JARs