関連ワード:  why we use static method in java    why we use static method in java 8    why we use static methods in javascript    why we need static method in java    why we use static function in java    why we use non static method in java    why we use static in main method in java    why we use static method in interface in java    why we use static keyword in method in java    why do we need static method in java 8 interfaces