Developer forums like StackOverflow have become essential resources to modern software development practices. However, many code snippets lack a well-defined method declaration, and thus they are often incomplete for immediate reuse. Developers must adapt the retrieved code snippets by parameterizing the variables involved and identifying the return value. This activity, which we call APIzation of a code snippet, can be tedious and time-consuming. In this paper, we present APIzator to perform APIzations of Java code snippets automatically. APIzator is grounded by four common patterns that we extracted by studying real APIzations in GitHub. APIzator presents a static analysis algorithm that automatically extracts the method parameters and return statements. We evaluated APIzator with a ground-truth of 200 APIzations collected from 20 developers. For 113 (56.50 %) and 115 (57.50 %) APIzations, APIzator and the developers extracted identical parameters and return statements, respectively. For 163 (81.50 %) APIzations, either the parameters or the return statements were identical.