關於「Runnable is a class present in Java lang package」標籤，搜尋引擎有相關的訊息討論：

Runnable (Java Platform SE 8 ) - Oracle Help Centerdocs.oracle.com › javase › docs › api › java › lang › Runn...Why don't you have to add an import statement for the java.lang ...stackoverflow.com › questions › why-dont-you-have-to-a...Runnable Interface in Java: Explanation an