read message use SimpleConsumer,can not start with assign offset

kafka version is 0.8.0, the code as https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Example

when i assign a offset ,it will throw java.lang.ArrayIndexOutOfBoundsException: 0

java.lang.ArrayIndexOutOfBoundsException: 0
at com.chen.test.consumer.SimpleConsumerClient.getLastOffset(SimpleConsumerClient.java:164)
at com.chen.test.consumer.SimpleConsumerClient.run(SimpleConsumerClient.java:80)
at com.chen.test.consumer.SimpleConsumerClient.main(SimpleConsumerClient.java:48)
##EarliestTime : -2 || -1 #### The Start Offset : -2
Error fetching data from the Broker:10.209.22.206 Reason: 1

how can is get the message which is assign offset?

Thanks，
Lax