Today "DT Big Data DreamWorks Video", 50th: Scala's variance change point and its application in Spark source resolution _controller
Potato: http://www.tudou.com/programs/view/85BX4YBSdSI/
Baidu Network disk: Http://pan.baidu.com/s/1kTINV0b?qq-pf-to=pcqq.group
Scala's type change point learning experience:
Scala is today's most important big data language.
Through this study, Little star mastered the basic knowledge of Scala type change point. 1.scala arrays do not support deformation. 2. Covariance requires that the elements in container is immutable.
In a covariant type, a subclass type parameter can be passed to the parent class constructor, and the parent class cannot pass the child class. And the inverse is just the opposite. Covariance is more likely to be used in Scala than to share errors, so please correct me, thank you.
DT Big Data Dream Factory
