Nowadays, Java programming is a popular language for novice students to be studied in universities. Since most of them have no experience in programming, they may not be familiar with even use of an editor. For their self-study, we have proposed Code Typing Problem (CTP) and Code Fixing Problem (CFP) in Java Programming Learning Assistant System (JPLAS). CTP asks to type a given code using a keyboard while looking at the example one. Besides, CFP asks to fix intentionally injected errors in the code by understanding the syntax and semantics. Previously, we assigned both problems to first-year undergraduate students in State Polytechnique of Malang, Indonesia, taking an introductory Java programming course. In this paper, we apply the t-test to their solution results to show that CFP is harder than CTP, and analyse details which errors are difficult for students. It is found that name errors are often missed by students.