Caused by: java.lang.NoSuchMethodException: org.apache.hadoop.hdfs.protocol.DatanodeBlocks.()

如果是在hadoop中遇到這個例外
則可能是某個有實作org.apache.hadoop.io.Writable的物件少了沒有引數(argument)的建植子(constructor)

just make sure the class which implements org.apache.hadoop.io.Writable does have a constructor
with no parameters.

Class.this

http://banana-in-black.blogspot.com/2011/09/javaclassthis.html

Stack overflow Java: Class.this

inner class 用來存取outer class時的用法
因為直接在inner class裡面用this的話只會指向該inner class