What should I know about Java before joining an MCA?

Java remains a practical language for enterprise software and application development. MCA students can strengthen their profile by learning object-oriented programming, collections, exception handling and database connectivity. For an MCA learner, the best way to understand Java is to connect the theory with a small working example. This point is specifically relevant to the Java aspect of MCA study. For this specific question about Java, the practical takeaway is to relate the concept to your own MCA learning goal. In other words, this guidance addresses: What should I know about Java before joining an MCA?