Hadoop I/O - Hadoop: The Definitive Guide - page 153

[173] 99 Three, four, shut the door
[220] 98 Five, six, pick up sticks
[264] 97 Seven, eight, lay them straight
[314] 96 Nine, ten, a big fat hen
[359] 95 One, two, buckle my shoe
[404] 94 Three, four, shut the door
[451] 93 Five, six, pick up sticks
[495] 92 Seven, eight, lay them straight
[545] 91 Nine, ten, a big fat hen
...
[1976] 60 One, two, buckle my shoe
[2021] 59 Three, four, shut the door
[2088] 58 Five, six, pick up sticks
[2132] 57 Seven, eight, lay them straight
[2182] 56 Nine, ten, a big fat hen
...
[4557] 5 One, two, buckle my shoe
[4602] 4 Three, four, shut the door
[4649] 3 Five, six, pick up sticks
[4693] 2 Seven, eight, lay them straight
[4743] 1 Nine, ten, a big fat hen
Reading a SequenceFile
Reading sequence files from beginning to end is a matter of creating an instance of
SequenceFile.Reader and iterating over records by repeatedly invoking one of the
next() methods. Which one you use depends on the serialization framework you are us-
ing. If you are using Writable types, you can use the next() method that takes a key
and a value argument and reads the next key and value in the stream into these variables:
public boolean next ( Writable key , Writable val )
The return value is true if a key-value pair was read and false if the end of the file has
been reached.
For other, non-Writable serialization frameworks (such as Apache Thrift), you should use
these two methods:
public Object next ( Object key ) throws IOException
public Object getCurrentValue ( Object val ) throws IOException
In this case, you need to make sure that the serialization you want to use has been set in
the io.serializations property; see Serialization Frameworks .