ReSwitcher: Automatically Refactoring Java Programs for Switch Expression

A switch statement is frequently used with the advantage of handling multi-way branches and with the disadvantage of fall-through semantics that makes programs error-prone. Since JDK 12, the switch expression has been proposed as an alternative to make the code cleaner and safer. However, none of existing works focuses on fall-through semantics and refactoring for switch expressions in Java programs. To this end, this paper presents a refactoring tool ReSwitcher that can automatically (i) remove the fall-through semantics from a switch statement; and (ii) convert a switch statement into a switch expression. ReSwitcher is evaluated on 5 real-world applications. The results show it can refactor 2,984 switch statements in an average of 2.71 seconds, which improves robustness for these projects.