Arraylist Class

Java Iterator is an interface that provides only the basic rules for iteration, and a foreach loop can be used for any container that implements the Iterable interface.

After completing the four basic learning steps of Apache Cassandra, you can try the actual code. If necessary, it is recommended to briefly review: Apache Cassandra Learning Step (1) Apache Cassandra Learning Ste ...

1, metadata (Metadata): Maintenance of HDFs file System file and directory information, divided into memory metadata and metadata file two kinds. Namenode maintains the entire metadata. HDFs implementation, the method of periodically exporting metadata is not adopted, but the backup mechanism of metadata mirroring file (fsimage) + day file (edits) is adopted. 2, Block: The contents of the file. Search path Flow: &http://www.aliyun.com/zixun/aggregation/37 ...

This article is my second time reading Hadoop 0.20.2 notes, encountered many problems in the reading process, and ultimately through a variety of ways to solve most of the. 　　Hadoop the whole system is well designed, the source code is worth learning distributed students read, will be all notes one by one post, hope to facilitate reading Hadoop source code, less detours. 1 serialization core Technology The objectwritable in 0.20.2 version Hadoop supports the following types of data format serialization: Data type examples say ...

This article describes the use of java iterators to traverse ArrayList collections, Set collections, and Map collections.

Iterator and iterable objects in Java. Let's take a look at the difference between these two objects and how to implement the for each loop in a custom class.

1, namenode Start load metadata scenario analysis Namenode function call Fsnamesystemm read dfs.http://www.aliyun.com/zixun/aggregation/11696.html "> Namenode.name.dir and Dfs.namenode.edits.dir build Fsdirectory. Fsimage class Recovertransitionread and ...

Java iterator is mainly used to manipulate collection objects in java. Java provides an iterator interface Iterator. Iterator can only move forward and cannot be rolled back.

Java Iterable interface and the Iterator interface. The class that implements the Iterable interface is iterable; the class that implements the Iterator interface is an iterator.

Hive is a very open system, many of which support user customization, including: File format: Text file,sequence file in memory format: Java integer/string, Hadoop intwritable/text User-supplied Map/reduce script: In any language, use Stdin/stdout to transmit data user-defined functions: Substr, Trim, 1–1 user-defined poly ...