Okay that makes sense .. so the same order I write is how I can read .. taking it a step further, in the compareto method, how can I use the bytes provided to do a comparison on let's say on a list object On Aug 31, 2013 4:52 PM, "Harsh J" <ha...@cloudera.com> wrote:
> The idea behind write(…) and readFields(…) is simply that of ordering. > You need to write your custom objects (i.e. a representation of them) > in order, and read them back in the same order. > > An example way of serializing a list would be to first serialize the > length (so you know how many you'll be needed to read back), and then > serialize each item appropriately, using delimiters, or using > length-prefixes just like lists. > > Mainly, you're required to tackle the serialization/deserialization on > your own. > > This is one of the reasons I highly recommend using a library like > Apache Avro instead. Its more powerful, faster, and yet simple to use: > http://avro.apache.org/docs/current/gettingstartedjava.html and > http://avro.apache.org/docs/current/mr.html. It is also popular and > carries first-grade support on several other hadoop-ecosystem > projects, such as Flume and Crunch. > > On Sun, Sep 1, 2013 at 1:23 AM, Adeel Qureshi <adeelmahm...@gmail.com> > wrote: > > I want to write a custom writablecomparable object with two List objects > > within it .. > > > > public class CompositeKey implements WritableComparable { > > > > private List<JsonKey> groupBy; > > private List<JsonKey> sortBy; > > ... > > } > > > > what I am not sure about is how to write > > > > readFields and write methods for this object. Any help would be > appreciated. > > > > Thanks > > Adeel > > > > -- > Harsh J >
