This is an important question, as you would need to know the different data types if you are getting into the field of Big Data.
For every data type in Java, you have an equivalent in Hadoop. Therefore, the following are some Hadoop-specific data types that you could use in your MapReduce program:
IntWritable
FloatWritable
LongWritable
DoubleWritable
BooleanWritable
ArrayWritable
MapWritable
ObjectWritable