how to execute two consecutive map-reduce pairs?

[hong]

Hi all

A job must be done in two pairs of map reduce, That is, Map1==>  
reduce1 ==> map2==>reduce2. "==>" means the output file of left is  
the input of the right.
To do that job, can I just create only one JobConf instance, and  
invoke JobClient.runJob(conf) once?

Is there any similar example?

Thank you, in advance!