To assist Java programming educations, we have developed a Web-based Java Programming Learning Assistant System (JPLAS). JPLAS provides fill-in-blank problems to let students study the grammar and the code structure for Java by filling blank elements in a high-quality code that are composed of reserved words, identifiers, and control symbols. However, students can answer the problems only when connected with the Internet, which limits the time and place for them to use JPLAS. In this paper, we implement the offline answering function for fill-in-blank problems in JPLAS. To avoid cheating by students, we adopt the hash function and the message authentication technique. We confirm the effectiveness of our proposal through applications to the Java programming course in our department.