Yes they can learn because Big Data is one of the demanding technologies in the current market. Coming to Big Data in that most of programming part is done with Java so it is easy for Java Developers to learn Big Data. Learning this technology will helps in better career opportunities. If you are passionate about this technology then I recommend you this Big Data Hadoop Course in collaboration with IBM which is offering by Intellipaat. This program will help you to learn all the technologies required to become a certified Big Data professional.
Before enrolling do check out this video on how Pankaj learnt Big Data being a Java developer with the help of Intellipaat training -