To enhance Java programming studies, we have developed a Web-based Java Programming Learning Assistant System (JPLAS) that offers several types of programming exercises with automatic grading functions to cover various levels of them. Among them, the code correction problem (CRP) requests a student to correct a given source code that have intentionally injected errors, so that it can pass the unit test on JUnit using test code that describes the specifications of the code such as names and data types of classes, methods, and variables. In Java, a lot of class libraries are available, which makes this language popular in various practical applications. Thus, the study of their proper use is important for students. In this paper, we extend CRP for class library studies by considering method names in class libraries for errors in the error injection algorithm. As the first step study, Wrapper classes are selected in generating CRP instances. We confirm the effectiveness of this extension through preliminary applications to 10 students in Okayama University.