The Java programming has been educated to students in a lot of universities and professional schools due to its reliability, portability, and easy learning. To assist the education, our group has developed a Java programming education assistant system based on the test-driven development method. However, this system targets students who have studied Java to some extent. In this paper, we propose the online fill-in-the-blank problem function for this Web system to assist the learning of the reserved words of Java for Java beginners. This function consists of the teacher service function and the student service function. By the former function, a teacher can generate a fill-in-the-blank problem automatically by removing the specified reserved words randomly from a sample Java code in the database. By the latter function, a student can repeatedly submit answers of a problem until all the answers are correct for self-study. The function is implemented at the existing system and is applied to students who are Java beginners, where the questionnaire result confirms the effectiveness of our proposal.