From another terminal, run the following command to run the consumer application which will read the events from the purchases topic and write the information to the terminal. 
./out/consumer
The consumer application will start and print any events it has not yet consumed and then wait for more events to arrive. On startup of the consumer, you should see output resembling this: 
Consumed event from topic purchases: ID = 890243:0:2, key = awalther   value = batteries
Consumed event from topic purchases: ID = 890243:1:2, key = htanaka    value = book
Consumed event from topic purchases: ID = 890243:2:2, key = jbernard   value = t-shirts
Consumed event from topic purchases: ID = 890243:3:2, key = eabara     value = gift card
Consumed event from topic purchases: ID = 890243:4:2, key = htanaka    value = batteries
Consumed event from topic purchases: ID = 890243:5:2, key = htanaka    value = book
Consumed event from topic purchases: ID = 890243:6:2, key = awalther   value = t-shirts
Consumed event from topic purchases: ID = 890243:7:2, key = awalther   value = t-shirts
Consumed event from topic purchases: ID = 890243:8:2, key = sgarcia    value = book
Consumed event from topic purchases: ID = 890243:9:2, key = awalther   value = gift card
Rerun the producer to see more events, or feel free to modify the code as necessary to create more or different events. Once you are done with the consumer, enter Ctrl-C to terminate the consumer application.